Generalization of Einstein's gravitational field equations

NASA Astrophysics Data System (ADS)

Moulin, Frédéric

2017-12-01

The Riemann tensor is the cornerstone of general relativity, but as is well known it does not appear explicitly in Einstein's equation of gravitation. This suggests that the latter may not be the most general equation. We propose here for the first time, following a rigorous mathematical treatment based on the variational principle, that there exists a generalized 4-index gravitational field equation containing the Riemann curvature tensor linearly, and thus the Weyl tensor as well. We show that this equation, written in n dimensions, contains the energy-momentum tensor for matter and that of the gravitational field itself. This new 4-index equation remains completely within the framework of general relativity and emerges as a natural generalization of the familiar 2-index Einstein equation. Due to the presence of the Weyl tensor, we show that this equation contains much more information, which fully justifies the use of a fourth-order theory.

[Photoeffects, Einstein's light quanta and the history of their acceptance].

PubMed

Wiederkehr, Karl Heinrich

2006-01-01

It is generally supposed, that the discovery of the efficacy-quantum by Planck was the impetus to Einstein's hypothesis of lightquanta. With its help Einstein could explain the external light-electrical effect. But even years before Einstein had worked at the photoeffect and already made experiments on it. For that reason the article gives a short survey about the history of the lightelectric effects. Lenard's basical work about the release of the photoelectrons is dealt with in detail, without which Einstein would scarcely have found his lightquanta. Furthermore it is shown how difficult it was for the physicists to give up--at least partially--the traditional view of the undulation-nature of light, and how they searched to explain the great energies of the photoelectrons. On the other side it is set forth how Einstein's formula of lightquanta was gradually confirmed. The tragical development of Einstein's personal relations with Johannes Stark and Philipp Lenard are briefly described. Stark was one of the few who supported Einstein's ideas at the beginning. Only with the Compton-effect, which could only be quantitatively interpreted by means of lightquanta and the special theory of relativity 1923, the way was free for the general acceptance of the lightquanta. Einstein did not agree to the obtained dualism of undulation and corpuscle; he had a different solution in mind about the fusion of the two forms of appearance of light.

Book Review: Book review

NASA Astrophysics Data System (ADS)

Wald, Robert M.

There is no question that the formulation of general relativity was one of the most remarkable episodes in the history of science. As a physicist and researcher in general relativity, the story of the formulation of general relativity that I have heard (and repeated) many times goes basically as follows: In 1907, Einstein obtained his fundamental insight-the "equivalence principle"-that gravitation and inertia are intimately connected; a freely falling observer does not "feel" gravitational force. It then took the genius of Einstein many years of "struggle"-during which he mastered the elements of differential geometry-to formulate a theory that properly incorporated this idea. In November, 1915, he finally succeeded in formulating general relativity.

The Origin of Gravitational Lensing: A Postscript to Einstein's 1936 Science Paper

PubMed

Renn; Sauer; Stachel

1997-01-10

Gravitational lensing, now taken as an important astrophysical consequence of the general theory of relativity, was found even before this theory was formulated but was discarded as a speculative idea without any chance of empirical confirmation. Reconstruction of some of Einstein's research notes dating back to 1912 reveals that he explored the possibility of gravitational lensing 3 years before completing his general theory of relativity. On the basis of preliminary insights into this theory, Einstein had already derived the basic features of the lensing effect. When he finally published the very same results 24 years later, it was only in response to prodding by an amateur scientist.

Comparison of Einstein-Boltzmann solvers for testing general relativity

NASA Astrophysics Data System (ADS)

Bellini, E.; Barreira, A.; Frusciante, N.; Hu, B.; Peirone, S.; Raveri, M.; Zumalacárregui, M.; Avilez-Lopez, A.; Ballardini, M.; Battye, R. A.; Bolliet, B.; Calabrese, E.; Dirian, Y.; Ferreira, P. G.; Finelli, F.; Huang, Z.; Ivanov, M. M.; Lesgourgues, J.; Li, B.; Lima, N. A.; Pace, F.; Paoletti, D.; Sawicki, I.; Silvestri, A.; Skordis, C.; Umiltà, C.; Vernizzi, F.

2018-01-01

We compare Einstein-Boltzmann solvers that include modifications to general relativity and find that, for a wide range of models and parameters, they agree to a high level of precision. We look at three general purpose codes that primarily model general scalar-tensor theories, three codes that model Jordan-Brans-Dicke (JBD) gravity, a code that models f (R ) gravity, a code that models covariant Galileons, a code that models Hořava-Lifschitz gravity, and two codes that model nonlocal models of gravity. Comparing predictions of the angular power spectrum of the cosmic microwave background and the power spectrum of dark matter for a suite of different models, we find agreement at the subpercent level. This means that this suite of Einstein-Boltzmann solvers is now sufficiently accurate for precision constraints on cosmological and gravitational parameters.

The Einstein tower : an intertexture of dynamic construction, relativity theory and astronomy

NASA Astrophysics Data System (ADS)

Hentschel, Klaus; Hentschel, Ann M.

This book focuses on the `Einstein Tower', an architecturally historic observatory built in Potsdam in 1920 to allow the German astronomer Erwin Finlay Freundlich to attempt to verify experimentally Einstein's general theory of relativity. Freundlich, who was the first German astronomer to show a genuine interest in Einstein's theory, managed to interest his architect friend Erich Mendelsohn in designing this unique building. To develop a full historical picture, the book interweaves several descriptive levels: the biography of Freundlich; the social context in which he interacted with teachers, co-workers, students, his patrons (including Einstein), and scientific opponents; the cognitive aspects of his attempts to verify Einstein's theory; the political milieu within the Berlin scientific research community; and a cross-national comparison of astrophysics. This is an interesting account of this unconventional tale in the history of science.

The Einstein/CFA stellar survey - Overview of the data and interpretation of results

NASA Technical Reports Server (NTRS)

Vaiana, G. S.

1981-01-01

Results are presented from an extensive survey of stellar X-ray emission, using the Einstein Observatory. Over 140 stars have been detected to date, throughout the H-R diagram, thus showing that soft X-ray emission is the norm rather than the exception for stars in general. This finding is strongly at odds with pre-Einstein expectations based on standard acoustic theories of coronal heating. Typical examples of stellar X-ray detections and an overview of the survey data are presented. In combination with recent results from solar X-ray observations, the new Einstein data argue for the general applicability of magnetic field-related coronal heating mechanisms.

The Spacetime Between Einstein and Kaluza-Klein: Further Explorations

NASA Astrophysics Data System (ADS)

Vuille, Chris

2017-01-01

Tensor multinomials can be used to create a generalization of Einstein's general relativity that in a mathematical sense falls between Einstein's original theory in four dimensions and the Kaluza-Klein theory in five dimensions. In the extended theory there are only four physical dimensions, but the tensor multinomials are expanded operators that can accommodate other forces of nature. The equivalent Ricci tensor of this geometry yields vacuum general relativity and electromagnetism, as well as a Klein-Gordon-like quantum scalar field. With a generalization of the stress-energy tensor, an exact solution for a plane-symmetric dust can be found where the scalar portion of the field drives early universe inflation, levels off for a period, then causes a later continued universal acceleration, a possible geometric mechanism for the inflaton or dark energy. Some new explorations of the equations, the problems, and possibilities will be presented and discussed.

Einstein: The Gourmet of Creativity.

ERIC Educational Resources Information Center

Greenberg, Joel

1979-01-01

Reports a psychiatrist's analysis of Einstein's personal account of how he developed the theory of relativity. The psychiatrist cites Janusian thinking, actively conceiving two or more opposite concepts simultaneously, as a characteristic of much creative thought in general. (MA)

Einstein's Jury -The Race to Test Relativity

NASA Astrophysics Data System (ADS)

Crelinsten, Jeffrey

2006-12-01

It is common belief that Einstein’s general theory of relativity won worldwide acceptance after British astronomers announced in November 1919 that the sun’s gravitational field bends starlight by an amount predicted by Einstein. This paper demonstrates that the case for Einstein was not settled until much later and that there was considerable confusion and debate about relativity during this period. Most astronomers considered Einstein’s general theory too metaphysical and abstruse, and many tried to find more conventional explanations of the astronomical observations. Two American announcements before the British results appeared had been contrary to Einstein’s prediction. They came from Lick and Mt. Wilson observatories, which enjoyed international reputations as two of the most advanced astrophysical research establishments in the world. Astronomers at these renowned institutions were instrumental in swaying the court of scientific opinion during the decade of the 1920s, which saw numerous attempts to measure light-bending, as well as solar line displacements and even ether-drift. How astronomers approached the “Einstein problem” in these early years before and after the First World War, and how the public reacted to what they reported, helped to shape attitudes we hold today about Einstein and his ideas.

Einstein Meets Hilbert: At the Crossroads of Physics and Mathematics

NASA Astrophysics Data System (ADS)

Rowe, David E.

One of the most famous episodes in the early history of general relativity involves the ``race'' in November 1915 between Albert Einstein and David Hilbert to uncover the ``correct'' form for the ten gravitational field equations. In light of recent archival findings, however, this story now has become a topic of renewed interest and controversy among historians of physics and mathematics. Drawing on recent studies and newly found sources, the present essay takes up this familiar tale from a new perspective, one that has seldom received due attention in the standard literature, namely, the mathematical issues at the heart of Einstein's theory. Told from this angle, the leading actors are Einstein's collaborator Marcel Grossmann, his critic Tullio Levi-Civita, his competitor David Hilbert, and several other mathematicians, many of them connected with Hilbert's Göttingen colleagues such as Hermann Weyl, Felix Klein, and Emmy Noether. As Einstein was the first to admit, Göttingen was far more important than Berlin as an active center for research in general relativity. Any account which, like this one, tries to understand both the actions and motives of the leading players must confront the problem of interpreting the rather sparse documentary evidence available. The interpretation offered herein, whatever its merits, aims first and foremost to show how mathematical issues deeply permeated the early history of general relativity.

The creativity of Einstein and astronomy

NASA Technical Reports Server (NTRS)

Zeldovich, Y. B.

1980-01-01

A discussion of Einstein's scientific achievements for the 100th anniversary of his birth is presented. His works dealing with thermodynamics are described, along with his quantum theory of radiation. Most of the article discusses his general theory of relativity.

Dutch museum marks Einstein anniversary

NASA Astrophysics Data System (ADS)

van Calmthout, Matijn

2016-01-01

A new painting of Albert Einstein's field equation from his 1915 general theory of relativity was unveiled in a ceremony in November 2015 by the Dutch physicist Robbert Dijkgraaf, who is director of the Princeton Institute for Advanced Study in the US.

Gravity Probe B: Examining Einstein's Spacetime with Gyroscopes. An Educator's Guide with Activities in Space Science.

ERIC Educational Resources Information Center

Range, Shannon K'doah; Mullins, Jennifer

This teaching guide introduces a relativity gyroscope experiment aiming to test two unverified predictions of Albert Einstein's general theory of relativity. An introduction to the theory includes the following sections: (1) "Spacetime, Curved Spacetime, and Frame-Dragging"; (2) "'Seeing' Spacetime with Gyroscopes"; (3)…

BOOK REVIEW: A Student's Guide to Einstein's Major Papers A Student's Guide to Einstein's Major Papers

NASA Astrophysics Data System (ADS)

Janssen, Michel

2013-12-01

The core of this volume is formed by four chapters (2-5) with detailed reconstructions of the arguments and derivations in four of Einstein's most important papers, the three main papers of his annus mirabilis 1905 (on the light quantum, Brownian motion, and special relativity) and his first systematic exposition of general relativity of 1916. The derivations are given in sufficient detail and in sufficiently modernized notation (without any serious distortion of the originals) for an undergraduate physics major to read and understand them with far less effort than it would take him or her to understand (English translations of) Einstein's original papers. Each of these four papers is accompanied by a detailed introduction, which covers the conceptual development of the relevant field prior to Einstein's contribution to it and corrects some of the myths surrounding these papers that still have not been fully eradicated among physicists. (One quibble: though Kennedy correctly points out that the goal of the light quantum paper was not to explain the photoelectric effect, it is also not quite right to say that 'it was written to explain the Wien region of blackbody radiation' (p. xv). Einstein used this explanatory feat as the central argument for his light quantum hypothesis.) These four chapters then are the most valuable part of the volume. They could be used, independently of one another, but preferably in conjunction with Einstein's original texts, in courses on quantum mechanics, statistical mechanics, electrodynamics, and general relativity, respectively, to add a historical component to such courses. As a historian of science embedded in a physics department who is regularly called upon to give guest lectures in such courses on the history of their subjects, I can highly recommend the volume for this purpose. However, I would not adopt this volume as (one of) the central text(s) for a course on the history of modern physics. For one thing, chapter 1, which in just 26 pages (not counting six pages of notes and references) covers everything from Copernicus, Galileo, Kepler and Newton to Maxwell and Lorentz to Einstein's early biography to a cardboard version of Popper versus Kuhn, is too superficial to be useful for such a course. To a lesser extent, this is also true for chapter 6, which compresses the development of quantum theory after Einstein's 1905 paper into 20 pages (plus seven pages of notes and references) and for chapter 7, a brief epilogue. However, this is not my main worry. One could easily supplement or even replace the bookends of the volume with other richer sources and use this volume mainly for its excellent detailed commentaries on some Einstein classics in the four chapters in between. My more serious reservation about the use of the volume as a whole in a history of physics course, ironically, comes from the exact same feature that made me whole-heartedly recommend its core chapters for physics courses. This is especially true for the chapters on special and general relativity. How useful is it for a student to go through, in as much detail as this volume provides, the Lorentz transformation of Maxwell's equations in vector form? I can see how a student in an E&M class (with a section on special relativity) might benefit from this exercise. The clumsiness of the calculations in vector form by Lorentz and Einstein could help a student encountering Maxwell's equations in tensor form for the first time appreciate the advantages of the latter formalism. Similarly, it would be useful for a student in a GR class to go through the basics of tensor calculus in the old-fashioned but not inelegant mathematical introduction of Einstein's 1916 review article on general relativity. This could reinforce mastery of material that a student in a GR class will have to learn anyway (though Einstein's presentation of the mathematics of both special and general relativity in The Meaning of Relativity would seem to be more suitable for these purposes). It is not so clear what benefit a student in a history of physics course rather than a E&M course or a GR course would derive from the exhaustive coverage of the papers on special and general relativity in this volume. In the case of the history of special relativity, it would seem to make sense to leave out the details of the Lorentz transformation of Maxwell's equations to make room for a discussion, even if only qualitatively, of Minkowski's four-dimensional formalism and Minkowski diagrams. In the case of the history of general relativity, coverage of tensor calculus could profitably be curtailed to make room for discussion of how Einstein found his field equations or how GR failed to make all motion relative. Chapter 3 on Brownian motion also contains its share of detailed calculations that may be useful for students in a class on Stat Mech but not for those in a class on history of physics. Chapter 2 on the light quantum paper does not suffer from this problem. However, whereas the other three papers covered in detail in the volume can serve as representative of Einstein's broader efforts in those fields, the light quantum paper is only the first in a series of remarkable contributions that Einstein made to early quantum theory. Several of these contributions (specific heat, wave-particle duality, stimulated emission, Bose--Einstein statistics) are covered very briefly in chapter 6. I would have liked to see a presentation of Einstein's 1917 derivation of the Planck law for the spectral distribution of black-body radiation with the famous A and B coefficients as detailed and as easy to follow as many less important derivations in the chapters on relativity and Brownian motion. This derivation is much easier yet much more illuminating than, say, the original proofs of the Lorentz invariance of Maxwell's equations. I hope the author will consider such changes in emphasis for a second edition, for his reconstructions and commentaries certainly do open up these four classic Einstein papers to interested undergraduates in physics and other disciplines in ways that the scholarly literature on Einstein does not.

A Staged Reading of the Play: TRANSCENDENCE: Relativity and Its Discontents by Robert Marc Friedman

NASA Astrophysics Data System (ADS)

Friedman, Robert Marc

2015-04-01

TRANSCENDENCE explores aspects of Einstein's life and his general theory of relativity at the time of the theory's creation and initial reception. While being faithful to historical scholarship, the play creates its own theatrical reality aiming to engage emotions and intellect. Those who strive for transcendence must nevertheless also confront the harsh realities of living in specific time-bound social contexts. Universal constants that anchor physical theory in an objective reality, as Einstein believed, do not readily have equivalents in notions of identity, duty, loyalty, and excellence. In November 1915 after toiling for years in Zurich, Prague, and now Berlin, Einstein achieved his general theory of relativity. When in 1919 British astronomers announced evidence for the bending of starlight by the sun as Einstein had predicted, he soon surprisingly found himself an international celebrity. Expectations arose that he would be called to Stockholm. But the Nobel Committee for Physics refused to acknowledge ``speculations'' such Einstein's. The dismissal of relativity entailed principled and biased opposition, and not simply mistakes in evaluation. Several committee members agreed that Einstein must not receive a Prize. Join us for a dramatic staged reading of TRANSCENDENCE, a play by the science historian Robert Marc Friedman (http://www.hf.uio.no/iakh/english/people/aca/robertfr/index.html) and directed by James Glossman, Lecturer in Directing and Shakespeare, Johns Hopkins University. After the performance, the playwright, director and actors will be available for a talk-back audience discussion.

Quintessence background for 5D Einstein-Gauss-Bonnet black holes

NASA Astrophysics Data System (ADS)

Ghosh, Sushant G.; Amir, Muhammed; Maharaj, Sunil D.

2017-08-01

As we know that the Lovelock theory is an extension of the general relativity to the higher-dimensions, in this theory the first- and the second-order terms correspond to general relativity and the Einstein-Gauss-Bonnet gravity, respectively. We obtain a 5D black hole solution in Einstein-Gauss-Bonnet gravity surrounded by the quintessence matter, and we also analyze their thermodynamical properties. Owing to the quintessence corrected black hole, the thermodynamic quantities have also been corrected except for the black hole entropy, and a phase transition is achievable. The phase transition for the thermodynamic stability is characterized by a discontinuity in the specific heat at r=r_C, with the stable (unstable) branch for r < (>) r_C.

Changes in concepts of time from Aristotle to Einstein

NASA Astrophysics Data System (ADS)

Sachs, Mendel

1996-03-01

The meaning of time and motion is discussed, at first tracing conceptual changes from Aristotle to Galileo/Newton to Einstein. Different views of ‘time’ in 20th century physics are then examined, with primary focus on the revolutionary changes that came with the theory of general relativity. Implications of its new view in all domains of physics are discussed — from elementary particles to cosmology. The special role of Hamilton's quaternion calculus in equations of motion in general relativity is shown.

Freud's superpotential in general relativity and in Einstein-Cartan theory

NASA Astrophysics Data System (ADS)

Böhmer, Christian G.; Hehl, Friedrich W.

2018-02-01

The identification of a suitable gravitational energy in theories of gravity has a long history, and it is well known that a unique answer cannot be given. In the first part of this paper we present a streamlined version of the derivation of Freud's superpotential in general relativity. It is found if we once integrate the gravitational field equation by parts. This allows us to extend these results directly to the Einstein-Cartan theory. Interestingly, Freud's original expression, first stated in 1939, remains valid even when considering gravitational theories in Riemann-Cartan or, more generally, in metric-affine spacetimes.

The Foundations of Einstein's Theory of Gravitation

NASA Astrophysics Data System (ADS)

Freundlich, Erwin; Brose, Translated by Henry L.; Einstein, Preface by Albert; Turner, Introduction by H. H.

2011-06-01

Introduction; 1. The special theory of relativity as a stepping-stone to the general theory of relativity; 2. Two fundamental postulates in the mathematical formulation of physical laws; 3. Concerning the fulfilment of the two postulates; 4. The difficulties in the principles of classical mechanics; 5. Einstein's theory of gravitation; 6. The verification of the new theory by actual experience; Appendix; Index.

A Classical Based Derivation of Time Dilation Providing First Order Accuracy to Schwarzschild's Solution of Einstein's Field Equations

NASA Astrophysics Data System (ADS)

Austin, Rickey W.

In Einstein's theory of Special Relativity (SR), one method to derive relativistic kinetic energy is via applying the classical work-energy theorem to relativistic momentum. This approach starts with a classical based work-energy theorem and applies SR's momentum to the derivation. One outcome of this derivation is relativistic kinetic energy. From this derivation, it is rather straight forward to form a kinetic energy based time dilation function. In the derivation of General Relativity a common approach is to bypass classical laws as a starting point. Instead a rigorous development of differential geometry and Riemannian space is constructed, from which classical based laws are derived. This is in contrast to SR's approach of starting with classical laws and applying the consequences of the universal speed of light by all observers. A possible method to derive time dilation due to Newtonian gravitational potential energy (NGPE) is to apply SR's approach to deriving relativistic kinetic energy. It will be shown this method gives a first order accuracy compared to Schwarzschild's metric. The SR's kinetic energy and the newly derived NGPE derivation are combined to form a Riemannian metric based on these two energies. A geodesic is derived and calculations compared to Schwarzschild's geodesic for an orbiting test mass about a central, non-rotating, non-charged massive body. The new metric results in high accuracy calculations when compared to Einsteins General Relativity's prediction. The new method provides a candidate approach for starting with classical laws and deriving General Relativity effects. This approach mimics SR's method of starting with classical mechanics when deriving relativistic equations. As a compliment to introducing General Relativity, it provides a plausible scaffolding method from classical physics when teaching introductory General Relativity. A straight forward path from classical laws to General Relativity will be derived. This derivation provides a minimum first order accuracy to Schwarzschild's solution to Einstein's field equations.

BOOK REVIEW: Partial Differential Equations in General Relativity

NASA Astrophysics Data System (ADS)

Halburd, Rodney G.

2008-11-01

Although many books on general relativity contain an overview of the relevant background material from differential geometry, very little attention is usually paid to background material from the theory of differential equations. This is understandable in a first course on relativity but it often limits the kinds of problems that can be studied rigorously. Einstein's field equations lie at the heart of general relativity. They are a system of partial differential equations (PDEs) relating the curvature of spacetime to properties of matter. A central part of most problems in general relativity is to extract information about solutions of these equations. Most standard texts achieve this by studying exact solutions or numerical and analytical approximations. In the book under review, Alan Rendall emphasises the role of rigorous qualitative methods in general relativity. There has long been a need for such a book, giving a broad overview of the relevant background from the theory of partial differential equations, and not just from differential geometry. It should be noted that the book also covers the basic theory of ordinary differential equations. Although there are many good books on the rigorous theory of PDEs, methods related to the Einstein equations deserve special attention, not only because of the complexity and importance of these equations, but because these equations do not fit into any of the standard classes of equations (elliptic, parabolic, hyperbolic) that one typically encounters in a course on PDEs. Even specifying exactly what ones means by a Cauchy problem in general relativity requires considerable care. The main problem here is that the manifold on which the solution is defined is determined by the solution itself. This means that one does not simply define data on a submanifold. Rendall's book gives a good overview of applications and results from the qualitative theory of PDEs to general relativity. It would be impossible to give detailed proofs of the main results in a self-contained book of reasonable length. Instead, the author concentrates on providing key definitions together with their motivations and explaining the main results, tools and difficulties for each topic. There is a section at the end of each chapter which points the reader to appropriate literature for further details. In this way, Rendall manages to describe the central issues concerning many subjects. Each of the twelve chapters (except for one on functional analysis) contains an important application to general relativity. For example, the chapter on ODEs discusses Bianchi spacetimes and the Einstein constraint equations are discussed in the chapter on elliptic equations. In the chapter on hyperbolic equations, the Einstein dust system is considered in the context of Leray hyperbolicity and Gowdy spacetimes are analysed in the section on Fuchsian methods. The book concludes with four chapters purely on applications to general relativity, namely The Cauchy problem for the Einstein equations, Global results, The Einstein-Vlasov system and The Einstein-scalar field systems. On reading this book, someone with a basic understanding of relativity could rapidly develop a picture, painted in broad brush strokes, of the main problems and tools in the area. It would be particularly useful for someone, such as a graduate student, just entering the field, or for someone who wants a general idea of the main issues. For those who want to go further, a lot more reading will be necessary but the author has sign-posted appropriate entry points to the literature throughout the book. Ultimately, this is a very technical subject and this book can only provide an overview. I believe that Alan Rendall's book is a valuable contribution to the field of mathematical relativity.

Einstein's creative thinking and the general theory of relativity: a documented report.

PubMed

Rothenberg, A

1979-01-01

A document written by Albert Einstein has recently come to light in which the eminent scientist described the actual sequence of his thoughts leading to the development of the general theory of relativity. The key creative thought was an instance of a type of creative cognition the author has previously designated "Janusian thinking," Janusian thinking consists of actively conceiving two or more opposite or antithetical concepts, ideas, or images simultaneously. This form of high-level secondary process cognition has been found to operate widely in art, science, and other fields.

Pure field theories and MACSYMA algorithms

NASA Technical Reports Server (NTRS)

Ament, W. S.

1977-01-01

A pure field theory attempts to describe physical phenomena through singularity-free solutions of field equations resulting from an action principle. The physics goes into forming the action principle and interpreting specific results. Algorithms for the intervening mathematical steps are sketched. Vacuum general relativity is a pure field theory, serving as model and providing checks for generalizations. The fields of general relativity are the 10 components of a symmetric Riemannian metric tensor; those of the Einstein-Straus generalization are the 16 components of a nonsymmetric. Algebraic properties are exploited in top level MACSYMA commands toward performing some of the algorithms of that generalization. The light cone for the theory as left by Einstein and Straus is found and simplifications of that theory are discussed.

Einstein's conversion from his static to an expanding universe

NASA Astrophysics Data System (ADS)

Nussbaumer, Harry

2014-02-01

In 1917 Einstein initiated modern cosmology by postulating, based on general relativity, a homogenous, static, spatially curved universe. To counteract gravitational contraction he introduced the cosmological constant. In 1922 Alexander Friedman showed that Albert Einstein's fundamental equations also allow dynamical worlds, and in 1927 Georges Lemaître, backed by observational evidence, concluded that our universe was expanding. Einstein impetuously rejected Friedman's as well as Lemaître's findings. However, in 1931 he retracted his former static model in favour of a dynamic solution. This investigation follows Einstein on his hesitating path from a static to the expanding universe. Contrary to an often advocated belief the primary motive for his switch was not observational evidence, but the realisation that his static model was unstable.

A novel biological 'twin-father' temporal paradox of General Relativity in a Gödel universe - Where reproductive biology meets theoretical physics.

PubMed

Ashrafian, Hutan

2018-03-01

Several temporal paradoxes exist in physics. These include General Relativity's grandfather and ontological paradoxes and Special Relativity's Langevin-Einstein twin-paradox. General relativity paradoxes can exist due to a Gödel universe that follows Gödel's closed timelike curves solution to Einstein's field equations. A novel biological temporal paradox of General Relativity is proposed based on reproductive biology's phenomenon of heteropaternal fecundation. Herein, dizygotic twins from two different fathers are the result of concomitant fertilization during one menstrual cycle. In this case an Oedipus-like individual exposed to a Gödel closed timelike curve would sire a child during his maternal fertilization cycle. As a consequence of heteropaternal superfecundation, he would father his own dizygotic twin and would therefore generate a new class of autofraternal superfecundation, and by doing so creating a 'twin-father' temporal paradox. Copyright © 2017 Elsevier Ltd. All rights reserved.

General Relativity and Energy

ERIC Educational Resources Information Center

Jackson, A. T.

1973-01-01

Reviews theoretical and experimental fundamentals of Einstein's theory of general relativity. Indicates that recent development of the theory of the continually expanding universe may lead to revision of the space-time continuum of the finite and unbounded universe. (CC)

A review of the contributions of Albert Einstein to earth sciences--in commemoration of the World Year of Physics.

PubMed

Martínez-Frías, Jesús; Hochberg, David; Rull, Fernando

2006-02-01

The World Year of Physics (2005) is an international celebration to commemorate the 100th anniversary of Einstein's "Annus Mirabilis." The United Nations has officially declared 2005 as the International Year of Physics. However, the impact of Einstein's ideas was not restricted to physics. Among numerous other disciplines, Einstein also made significant and specific contributions to Earth Sciences. His geosciences-related letters, comments, and scientific articles are dispersed, not easily accessible, and are poorly known. The present review attempts to integrate them as a tribute to Einstein in commemoration of this centenary. These contributions can be classified into three basic areas: geodynamics, geological (planetary) catastrophism, and fluvial geomorphology. Regarding geodynamics, Einstein essentially supported Hapgood's very controversial theory called Earth Crust Displacement. With respect to geological (planetary) catastrophism, it is shown how the ideas of Einstein about Velikovsky's proposals evolved from 1946 to 1955. Finally, in relation to fluvial geodynamics, the review incorporates the elegant work in which Einstein explains the formation of meandering rivers. A general analysis of his contributions is also carried out from today's perspective. Given the interdisciplinarity and implications of Einstein's achievements to multiple fields of knowledge, we propose that the year 2005 serve, rather than to confine his universal figure within a specific scientific area, to broaden it for a better appreciation of this brilliant scientist in all of his dimensions.

Energy distributions of Bianchi type-VI h Universe in general relativity and teleparallel gravity

NASA Astrophysics Data System (ADS)

Özkurt, Ş.; eref; Aygün, Sezg&idot; n.

2017-04-01

In this paper, we have investigated the energy and momentum density distributions for the inhomogeneous generalizations of homogeneous Bianchi type-VI h metric with Einstein, Bergmann-Thomson, Landau-Lifshitz, Papapetrou, Tolman and Møller prescriptions in general relativity (GR) and teleparallel gravity (TG). We have found exactly the same results for Einstein, Bergmann-Thomson and Landau-Lifshitz energy-momentum distributions in Bianchi type-VI h metric for different gravitation theories. The energy-momentum distributions of the Bianchi type- VI h metric are found to be zero for h = -1 in GR and TG. However, our results agree with Tripathy et al, Tryon, Rosen and Aygün et al.

Curved spaces before Einstein: Karl Schwarzschild's cosmological speculations and the beginnings of relativistic cosmology (German Title: Gekrümmte Universen vor Einstein: Karl Schwarzschilds kosmologische Spekulationen und die Anfänge der relativistischen Kosmologie)

NASA Astrophysics Data System (ADS)

Schemmel, Matthias

In contrast to most of his collegues in astronomy and physics, the German astronomer Karl Schwarzschild immediately recognized the significance of general relativity for physics and astronomy, and played a pioneering role in its early development. In this contribution, it is argued that the clue for understanding Schwarzschild's exceptional reaction to general relativity lies in the study of his prerelativistic work. Long before the rise of general relativity, Schwarzschild occupied himself with foundational problems on the borderline of physics, astronomy, and mathematics that, from today's perspective, belong to the field of problems of that theory. In this contribution, the example of Schwarzschild's early speculations about the non-Euclidean nature of physical space on cosmological scales is presented and their reflection in his reception of general relativity is discussed.

Einstein-Gauss-Bonnet theory of gravity: The Gauss-Bonnet-Katz boundary term

NASA Astrophysics Data System (ADS)

Deruelle, Nathalie; Merino, Nelson; Olea, Rodrigo

2018-05-01

We propose a boundary term to the Einstein-Gauss-Bonnet action for gravity, which uses the Chern-Weil theorem plus a dimensional continuation process, such that the extremization of the full action yields the equations of motion when Dirichlet boundary conditions are imposed. When translated into tensorial language, this boundary term is the generalization to this theory of the Katz boundary term and vector for general relativity. The boundary term constructed in this paper allows to deal with a general background and is not equivalent to the Gibbons-Hawking-Myers boundary term. However, we show that they coincide if one replaces the background of the Katz procedure by a product manifold. As a first application we show that this Einstein Gauss-Bonnet Katz action yields, without any extra ingredients, the expected mass of the Boulware-Deser black hole.

Averaging problem in general relativity, macroscopic gravity and using Einstein's equations in cosmology.

NASA Astrophysics Data System (ADS)

Zalaletdinov, R. M.

1998-04-01

The averaging problem in general relativity is briefly discussed. A new setting of the problem as that of macroscopic description of gravitation is proposed. A covariant space-time averaging procedure is described. The structure of the geometry of macroscopic space-time, which follows from averaging Cartan's structure equations, is described and the correlation tensors present in the theory are discussed. The macroscopic field equations (averaged Einstein's equations) derived in the framework of the approach are presented and their structure is analysed. The correspondence principle for macroscopic gravity is formulated and a definition of the stress-energy tensor for the macroscopic gravitational field is proposed. It is shown that the physical meaning of using Einstein's equations with a hydrodynamic stress-energy tensor in looking for cosmological models means neglecting all gravitational field correlations. The system of macroscopic gravity equations to be solved when the correlations are taken into consideration is given and described.

Einstein versus the Simple Pendulum Formula: Does Gravity Slow All Clocks?

ERIC Educational Resources Information Center

Puri, Avinash

2015-01-01

According to the Newtonian formula for a simple pendulum, the period of a pendulum is inversely proportional to the square root of "g", the gravitational field strength. Einstein's theory of general relativity leads to the result that time slows down where gravity is intense. The two claims look contradictory and can muddle student and…

Schwinger's Approach to Einstein's Gravity

NASA Astrophysics Data System (ADS)

Milton, Kim

2012-05-01

Albert Einstein was one of Julian Schwinger's heroes, and Schwinger was greatly honored when he received the first Einstein Prize (together with Kurt Godel) for his work on quantum electrodynamics. Schwinger contributed greatly to the development of a quantum version of gravitational theory, and his work led directly to the important work of (his students) Arnowitt, Deser, and DeWitt on the subject. Later in the 1960's and 1970's Schwinger developed a new formulation of quantum field theory, which he dubbed Source Theory, in an attempt to get closer contact to phenomena. In this formulation, he revisited gravity, and in books and papers showed how Einstein's theory of General Relativity emerged naturally from one physical assumption: that the carrier of the gravitational force is a massless, helicity-2 particle, the graviton. (There has been a minor dispute whether gravitational theory can be considered as the massless limit of a massive spin-2 theory; Schwinger believed that was the case, while Van Dam and Veltman concluded the opposite.) In the process, he showed how all of the tests of General Relativity could be explained simply, without using the full machinery of the theory and without the extraneous concept of curved space, including such effects as geodetic precession and the Lense-Thirring effect. (These effects have now been verified by the Gravity Probe B experiment.) This did not mean that he did not accept Einstein's equations, and in his book and full article on the subject, he showed how those emerge essentially uniquely from the assumption of the graviton. So to speak of Schwinger versus Einstein is misleading, although it is true that Schwinger saw no necessity to talk of curved spacetime. In this talk I will lay out Schwinger's approach, and the connection to Einstein's theory.

Induced matter brane gravity and Einstein static universe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heydarzade, Y.; Darabi, F., E-mail: heydarzade@azaruniv.edu, E-mail: f.darabi@azaruniv.edu

We investigate stability of the Einstein static universe against the scalar, vector and tensor perturbations in the context of induced matter brane gravity. It is shown that in the framework of this model, the Einstein static universe has a positive spatial curvature. In contrast to the classical general relativity, it is found that a stable Einstein static universe against the scalar perturbations does exist provided that the variation of time dependent geometrical equation of state parameter is proportional to the minus of the variation of the scale factor, δ ω{sub g}(t) = −Cδ a(t). We obtain neutral stability against the vector perturbations, and themore » stability against the tensor perturbations is guaranteed due to the positivity of the spatial curvature of the Einstein static universe in induced matter brane gravity.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohapi, N.; Hees, A.; Larena, J., E-mail: n.mohapi@gmail.com, E-mail: a.hees@ru.ac.za, E-mail: j.larena@ru.ac.za

The Einstein Equivalence Principle is a fundamental principle of the theory of General Relativity. While this principle has been thoroughly tested with standard matter, the question of its validity in the Dark sector remains open. In this paper, we consider a general tensor-scalar theory that allows to test the equivalence principle in the Dark sector by introducing two different conformal couplings to standard matter and to Dark matter. We constrain these couplings by considering galactic observations of strong lensing and of velocity dispersion. Our analysis shows that, in the case of a violation of the Einstein Equivalence Principle, data favourmore » violations through coupling strengths that are of opposite signs for ordinary and Dark matter. At the same time, our analysis does not show any significant deviations from General Relativity.« less

Stability of stationary-axisymmetric black holes in vacuum general relativity to axisymmetric electromagnetic perturbations

NASA Astrophysics Data System (ADS)

Prabhu, Kartik; Wald, Robert M.

2018-01-01

We consider arbitrary stationary and axisymmetric black holes in general relativity in (d +1) dimensions (with d ≥slant 3 ) that satisfy the vacuum Einstein equation and have a non-degenerate horizon. We prove that the canonical energy of axisymmetric electromagnetic perturbations is positive definite. This establishes that all vacuum black holes are stable to axisymmetric electromagnetic perturbations. Our results also hold for asymptotically de Sitter black holes that satisfy the vacuum Einstein equation with a positive cosmological constant. Our results also apply to extremal black holes provided that the initial perturbation vanishes in a neighborhood of the horizon.

The relativity revolution from the perspective of historical epistemology.

PubMed

Renn, Jürgen

2004-12-01

This essay analyzes Einstein's relativity revolution as part of a long-term development of knowledge in which the knowledge system of classical physics was reorganized in a process of reflection, described here as a "Copernican process." This process led in 1905 to the introduction of fundamentally new concepts of space, time, matter, and radiation. On the basis of an extensive historical reconstruction, the heuristics of Einstein's creation of the general theory of relativity, completing the relativity revolution, is interpreted as a further transformation of the knowledge of classical physics, starting from conceiving gravitation as a borderline problem between field theory and mechanics. The essay thus provides an answer to the puzzle of how Einstein was able to create a theory capable of accounting for a wide range of phenomena that were discovered only much later.

Spinning fluids in general relativity. II - Self-consistent formulation

NASA Technical Reports Server (NTRS)

Ray, John R.; Smalley, Larry, L.; Krisch, Jean P.

1987-01-01

Methods used earlier to derive the equations of motion for a spinning fluid in the Einstein-Cartan theory are specialized to the case of general relativity. The main idea is to include the spin as a thermodynamic variable in the theory.

Gravitational consequences of modern field theories

NASA Technical Reports Server (NTRS)

Horowitz, Gary T.

1989-01-01

Some gravitational consequences of certain extensions of Einstein's general theory of relativity are discussed. These theories are not alternative theories of gravity in the usual sense. It is assumed that general relativity is the appropriate description of all gravitational phenomena which were observed to date.

Critical remarks on Bruno Thuring's polemic against Einstein.

NASA Astrophysics Data System (ADS)

Kerschbaum, F.; Lackner, K.; Posch, T.

2005-08-01

Bruno Thüring (1905-1989) was among those scientists who joined the campaign against Einstein's Theories of Relativity which was undertaken in the name of so-called "German Physics". Thüring served as director of Vienna's University Observatory between 1940-45; hence, we present biographical information on his scientific and administrative activities in Vienna, partly based on interviews with time-witnesses. It is one of Thüring's basic convictions that Einstein's work cannot be understood without an analysis of the developments of physics and philosophy in the 19th century. While this is true generally, Thüring's account of these developments is rather superficial. For example, Thüring considers Kant's idea of the a priori status of geometry as a wholly sufficient epistemological foundation of mechanics, while both post-Kantian idealism and positivism were a mere backdrop to the development of knowledge - a view which can hardly stand critical examination. Concerning the impact of Einstein's theories on physics, Thüring argues that the principles of special and general relativity be nothing else but arbitrary decisions (as opposed to real insights). Hence these principles would never be verified or falsified by any experiment. The Michelson-Moreley experiment, e.g., would not prove the principles of special relativity. Thüring considers Einstein's interpretation of this experiment as premature and as an arbitrary judgement on a very particular and subaltern phenomenon which would not justify the conclusion that the velocity of the Earth with respect to the luminiferous aether be immeasurable by just any experimental technique.

The Concept of General Relativity is not Related to Reality

NASA Astrophysics Data System (ADS)

Kotas, Ronald

2015-04-01

The concept of general relativity is not related to reality. It is not real or factual Science. GR cannot account for objects falling to earth or for the weight of objects sitting on the earth. The Cavendish demonstration showing the attraction between two masses at right angles to earth's gravity, is not explained by GR. No one can prove the existence of ``space fabric.'' The concept of ``space time'' effects causing gravitational attraction between masses is wrong. Conservation law of energy - momentum does not exist in GR. LIGO fails in detecting ``gravity waves'' because there is no ``space fabric'' to transmit them. The Gravity B Probe data manipulated to show some effects, is not proof of ``space fabric.'' It is Nuclear Quantum Gravitation that provides clear definitive explanation of Gravity and Gravitation. It is harmonious with Newtonian and Quantum Mechanics, and Scientific Logic. Nuclear Quantum Gravitation has 10 clear, Scientific proofs and 21 more good indications. With this theory the Physical Forces are Unified. See: OBSCURANTISM ON EINSTEIN GRAVITATION? http://www.santilli-foundation.org/inconsistencies-gravitation.php and Einstein's Theory of Relativity versus Classical Mechanics, by Paul Marmet http://www.newtonphysics.on.ca/einstein/

Casimir effect in the rainbow Einstein's universe

NASA Astrophysics Data System (ADS)

Bezerra, V. B.; Mota, H. F.; Muniz, C. R.

2017-10-01

In the present paper we investigate the effects caused by the modification of the dispersion relation obtained by solving the Klein-Gordon equation in the closed Einstein's universe in the context of rainbow's gravity models. Thus, we analyse how the quantum vacuum fluctuations of the scalar field are modified when compared with the results obtained in the usual General Relativity scenario. The regularization, and consequently the renormalization, of the vacuum energy is performed adopting the Epstein-Hurwitz and Riemann's zeta functions.

Einstein's physical strategy, energy conservation, symmetries, and stability: "But Grossmann & I believed that the conservation laws were not satisfied"

NASA Astrophysics Data System (ADS)

Pitts, J. Brian

2016-05-01

Recent work on the history of General Relativity by Renn et al. shows that Einstein found his field equations partly by a physical strategy including the Newtonian limit, the electromagnetic analogy, and energy conservation. Such themes are similar to those later used by particle physicists. How do Einstein's physical strategy and the particle physics derivations compare? What energy-momentum complex(es) did he use and why? Did Einstein tie conservation to symmetries, and if so, to which? How did his work relate to emerging knowledge (1911-1914) of the canonical energy-momentum tensor and its translation-induced conservation? After initially using energy-momentum tensors hand-crafted from the gravitational field equations, Einstein used an identity from his assumed linear coordinate covariance xμ‧ = Mνμ xν to relate it to the canonical tensor. Usually he avoided using matter Euler-Lagrange equations and so was not well positioned to use or reinvent the Herglotz-Mie-Born understanding that the canonical tensor was conserved due to translation symmetries, a result with roots in Lagrange, Hamilton and Jacobi. Whereas Mie and Born were concerned about the canonical tensor's asymmetry, Einstein did not need to worry because his Entwurf Lagrangian is modeled not so much on Maxwell's theory (which avoids negative-energies but gets an asymmetric canonical tensor as a result) as on a scalar theory (the Newtonian limit). Einstein's theory thus has a symmetric canonical energy-momentum tensor. But as a result, it also has 3 negative-energy field degrees of freedom (later called "ghosts" in particle physics). Thus the Entwurf theory fails a 1920s-1930s a priori particle physics stability test with antecedents in Lagrange's and Dirichlet's stability work; one might anticipate possible gravitational instability. This critique of the Entwurf theory can be compared with Einstein's 1915 critique of his Entwurf theory for not admitting rotating coordinates and not getting Mercury's perihelion right. One can live with absolute rotation but cannot live with instability. Particle physics also can be useful in the historiography of gravity and space-time, both in assessing the growth of objective knowledge and in suggesting novel lines of inquiry to see whether and how Einstein faced the substantially mathematical issues later encountered in particle physics. This topic can be a useful case study in the history of science on recently reconsidered questions of presentism, whiggism and the like. Future work will show how the history of General Relativity, especially Noether's work, sheds light on particle physics.

Non-local Effects of Conformal Anomaly

NASA Astrophysics Data System (ADS)

Meissner, Krzysztof A.; Nicolai, Hermann

2018-03-01

It is shown that the nonlocal anomalous effective actions corresponding to the quantum breaking of the conformal symmetry can lead to observable modifications of Einstein's equations. The fact that Einstein's general relativity is in perfect agreement with all observations including cosmological or recently observed gravitational waves imposes strong restrictions on the field content of possible extensions of Einstein's theory: all viable theories should have vanishing conformal anomalies. It is shown that a complete cancellation of conformal anomalies in D=4 for both the C^2 invariant and the Euler (Gauss-Bonnet) invariant can only be achieved for N-extended supergravity multiplets with N ≥ 5.

The Einstein-Vlasov System/Kinetic Theory.

PubMed

Andréasson, Håkan

2011-01-01

The main purpose of this article is to provide a guide to theorems on global properties of solutions to the Einstein-Vlasov system. This system couples Einstein's equations to a kinetic matter model. Kinetic theory has been an important field of research during several decades in which the main focus has been on non-relativistic and special relativistic physics, i.e., to model the dynamics of neutral gases, plasmas, and Newtonian self-gravitating systems. In 1990, Rendall and Rein initiated a mathematical study of the Einstein-Vlasov system. Since then many theorems on global properties of solutions to this system have been established. This paper gives introductions to kinetic theory in non-curved spacetimes and then the Einstein-Vlasov system is introduced. We believe that a good understanding of kinetic theory in non-curved spacetimes is fundamental to a good comprehension of kinetic theory in general relativity.

Solutions to horava gravity.

PubMed

Lü, H; Mei, Jianwei; Pope, C N

2009-08-28

Recently Horava proposed a nonrelativistic renormalizable theory of gravitation, which reduces to Einstein's general relativity at large distances, and that may provide a candidate for a UV completion of Einstein's theory. In this Letter, we derive the full set of equations of motion, and then we obtain spherically symmetric solutions and discuss their properties. We also obtain solutions for the Friedmann-Lemaître-Robertson-Walker cosmological metric.

Probing Students' Ideas of the Principle of Equivalence

ERIC Educational Resources Information Center

Bandyopadhyay, Atanu; Kumar, Arvind

2011-01-01

The principle of equivalence was the first vital clue to Einstein in his extension of special relativity to general relativity, the modern theory of gravitation. In this paper we investigate in some detail students' understanding of this principle in a variety of contexts, when they are undergoing an introductory course on general relativity. The…

Bose-Einstein condensation in microgravity.

PubMed

van Zoest, T; Gaaloul, N; Singh, Y; Ahlers, H; Herr, W; Seidel, S T; Ertmer, W; Rasel, E; Eckart, M; Kajari, E; Arnold, S; Nandi, G; Schleich, W P; Walser, R; Vogel, A; Sengstock, K; Bongs, K; Lewoczko-Adamczyk, W; Schiemangk, M; Schuldt, T; Peters, A; Könemann, T; Müntinga, H; Lämmerzahl, C; Dittus, H; Steinmetz, T; Hänsch, T W; Reichel, J

2010-06-18

Albert Einstein's insight that it is impossible to distinguish a local experiment in a "freely falling elevator" from one in free space led to the development of the theory of general relativity. The wave nature of matter manifests itself in a striking way in Bose-Einstein condensates, where millions of atoms lose their identity and can be described by a single macroscopic wave function. We combine these two topics and report the preparation and observation of a Bose-Einstein condensate during free fall in a 146-meter-tall evacuated drop tower. During the expansion over 1 second, the atoms form a giant coherent matter wave that is delocalized on a millimeter scale, which represents a promising source for matter-wave interferometry to test the universality of free fall with quantum matter.

On the invariant mass conjecture in general relativity

NASA Astrophysics Data System (ADS)

Chruściel, Piotr T.

1988-06-01

An asymptotic symmetries theorem is proved under certain hypotheses on the behaviour of the metric at spatial infinity. This implies that the Einstein-von Freud-ADM mass can be invariantly assigned to an asymptotically flat four dimensional end of an asymptotically empty solution of Einstein equations if the metric is a no-radiation metric or if the end is defined in terms of a collection of boost-type domains.

The Adolescence of Relativity: Einstein, Minkowski, and the Philosophy of Space and Time

NASA Astrophysics Data System (ADS)

Dieks, Dennis

An often repeated account of the genesis of special relativity tells us that relativity theory was to a considerable extent the fruit of an operationalist philosophy of science. Indeed, Einstein's 1905 paper stresses the importance of rods and clocks for giving concrete physical content to spatial and temporal notions. I argue, however, that it would be a mistake to read too much into this. Einstein's operationalist remarks should be seen as serving rhetoric purposes rather than as attempts to promulgate a particular philosophical position - in fact, Einstein never came close to operationalism in any of his philosophical writings. By focussing on what could actually be measured with rods and clocks Einstein shed doubt on the empirical status of a number of pre-relativistic concepts, with the intention to persuade his readers that the applicability of these concepts was not obvious. This rhetoric manoeuvre has not always been rightly appreciated in the philosophy of physics. Thus, the influence of operationalist misinterpretations, according to which associated operations strictly define what a concept means, can still be felt in present-day discussions about the conventionality of simultaneity.The standard story continues by pointing out that Minkowski in 1908 supplanted Einstein's approach with a realist spacetime account that has no room for a foundational role of rods and clocks: relativity theory became a description of a four-dimensional "absolute world." As it turns out, however, it is not at all clear that Minkowski was proposing a substantivalist position with respect to spacetime. On the contrary, it seems that from a philosophical point of view Minkowski's general position was not very unlike the one in the back of Einstein's mind. However, in Minkowski's formulation of special relativity it becomes more explicit that the content of spatiotemporal concepts relates to considerations about the form of physical laws. If accepted, this position has important consequences for the discussion about the conventionality of simultaneity.

Effective temperatures and the breakdown of the Stokes-Einstein relation for particle suspensions.

PubMed

Mendoza, Carlos I; Santamaría-Holek, I; Pérez-Madrid, A

2015-09-14

The short- and long-time breakdown of the classical Stokes-Einstein relation for colloidal suspensions at arbitrary volume fractions is explained here by examining the role that confinement and attractive interactions play in the intra- and inter-cage dynamics executed by the colloidal particles. We show that the measured short-time diffusion coefficient is larger than the one predicted by the classical Stokes-Einstein relation due to a non-equilibrated energy transfer between kinetic and configuration degrees of freedom. This transfer can be incorporated in an effective kinetic temperature that is higher than the temperature of the heat bath. We propose a Generalized Stokes-Einstein relation (GSER) in which the effective temperature replaces the temperature of the heat bath. This relation then allows to obtain the diffusion coefficient once the viscosity and the effective temperature are known. On the other hand, the temporary cluster formation induced by confinement and attractive interactions of hydrodynamic nature makes the long-time diffusion coefficient to be smaller than the corresponding one obtained from the classical Stokes-Einstein relation. Then, the use of the GSER allows to obtain an effective temperature that is smaller than the temperature of the heat bath. Additionally, we provide a simple expression based on a differential effective medium theory that allows to calculate the diffusion coefficient at short and long times. Comparison of our results with experiments and simulations for suspensions of hard and porous spheres shows an excellent agreement in all cases.

A centennial gift from Einstein

NASA Astrophysics Data System (ADS)

Oswalt, T. D.

2017-06-01

The 1919 detection of the apparent displacement of background stars near the edge of the eclipsed Sun's disk provided one of the first convincing proofs of Einstein's theory of general relativity (1, 2). Almost 100 years later, Sahu et al. report on page 1046 of this issue the first measurement of the gravitational deflection of starlight by a star other than the Sun (3). Using the superior angular resolution of the Hubble Space Telescope (HST), they measured shifts in the apparent position of a distant background star as a nearby dense stellar remnant called a white dwarf passed almost in front of it in 2014. Because of the relative distances involved, the deflections they observed were about 1000 times smaller than those seen in 1919, but also in agreement with general relativity theory.

Regular black holes in Einstein-Gauss-Bonnet gravity

NASA Astrophysics Data System (ADS)

Ghosh, Sushant G.; Singh, Dharm Veer; Maharaj, Sunil D.

2018-05-01

Einstein-Gauss-Bonnet theory, a natural generalization of general relativity to a higher dimension, admits a static spherically symmetric black hole which was obtained by Boulware and Deser. This black hole is similar to its general relativity counterpart with a curvature singularity at r =0 . We present an exact 5D regular black hole metric, with parameter (k >0 ), that interpolates between the Boulware-Deser black hole (k =0 ) and the Wiltshire charged black hole (r ≫k ). Owing to the appearance of the exponential correction factor (e-k /r2), responsible for regularizing the metric, the thermodynamical quantities are modified, and it is demonstrated that the Hawking-Page phase transition is achievable. The heat capacity diverges at a critical radius r =rC, where incidentally the temperature is maximum. Thus, we have a regular black hole with Cauchy and event horizons, and evaporation leads to a thermodynamically stable double-horizon black hole remnant with vanishing temperature. The entropy does not satisfy the usual exact horizon area result of general relativity.

The collected papers of Albert Einstein. Volume 2. The Swiss years: Writings, 1900-1909

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stachel, J.; Cassidy, D.C.; Renn, J.

1989-01-01

This second volume of the papers of Albert Einstein chronologically presents published articles, unpublished papers, research and lecture notes, reviews, and patent applications for the period 1900-1909 during which time Einstein had a two-year period of short-term employment and a permanent position at the Swiss Patent Office in Bern. There are 62 published documents reproduced. The writings of this period deal with seven general themes: molecular forces, the foundation of statistical physics, the quantum hypothesis, determining molecular dimensions, Brownian movement, the theory of relativity, and the electrodynamics of moving media. The book also presents all available letters written by Einsteinmore » along with all significant letters sent to him and many important third-party letters written about him. The editors have added substantial introduction and a set of eight editorial notes that place Einstein's writings within their immediate scientific context. Footnotes to Einstein texts designed to illuminate the sources of scientific problems that Einstein confronted and the ideas and techniques with which he addressed them have been added by the editors. A comprehensive index to Einstein's early writings is provided.« less

A family of solutions to the Einstein-Maxwell system of equations describing relativistic charged fluid spheres

NASA Astrophysics Data System (ADS)

Komathiraj, K.; Sharma, Ranjan

2018-05-01

In this paper, we present a formalism to generate a family of interior solutions to the Einstein-Maxwell system of equations for a spherically symmetric relativistic charged fluid sphere matched to the exterior Reissner-Nordström space-time. By reducing the Einstein-Maxwell system to a recurrence relation with variable rational coefficients, we show that it is possible to obtain closed-form solutions for a specific range of model parameters. A large class of solutions obtained previously are shown to be contained in our general class of solutions. We also analyse the physical viability of our new class of solutions.

Quantum computational complexity, Einstein's equations and accelerated expansion of the Universe

NASA Astrophysics Data System (ADS)

Ge, Xian-Hui; Wang, Bin

2018-02-01

We study the relation between quantum computational complexity and general relativity. The quantum computational complexity is proposed to be quantified by the shortest length of geodesic quantum curves. We examine the complexity/volume duality in a geodesic causal ball in the framework of Fermi normal coordinates and derive the full non-linear Einstein equation. Using insights from the complexity/action duality, we argue that the accelerated expansion of the universe could be driven by the quantum complexity and free from coincidence and fine-tunning problems.

"Einstein's Playground": An Interactive Planetarium Show on Special Relativity

ERIC Educational Resources Information Center

Sherin, Zachary; Tan, Philip; Fairweather, Heather; Kortemeyer, Gerd

2017-01-01

The understanding of many aspects of astronomy is closely linked with relativity and the finite speed of light, yet relativity is generally not discussed in great detail during planetarium shows for the general public. One reason may be the difficulty to visualize these phenomena in a way that is appropriate for planetariums; another may be their…

Dark matter as a ghost free conformal extension of Einstein theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barvinsky, A.O., E-mail: barvin@td.lpi.ru

We discuss ghost free models of the recently suggested mimetic dark matter theory. This theory is shown to be a conformal extension of Einstein general relativity. Dark matter originates from gauging out its local Weyl invariance as an extra degree of freedom which describes a potential flow of the pressureless perfect fluid. For a positive energy density of this fluid the theory is free of ghost instabilities, which gives strong preference to stable configurations with a positive scalar curvature and trace of the matter stress tensor. Instabilities caused by caustics of the geodesic flow, inherent in this model, serve asmore » a motivation for an alternative conformal extension of Einstein theory, based on the generalized Proca vector field. A potential part of this field modifies the inflationary stage in cosmology, whereas its rotational part at the post inflationary epoch might simulate rotating flows of dark matter.« less

BV-BFV approach to general relativity: Einstein-Hilbert action

NASA Astrophysics Data System (ADS)

Cattaneo, Alberto S.; Schiavina, Michele

2016-02-01

The present paper shows that general relativity in the Arnowitt-Deser-Misner formalism admits a BV-BFV formulation. More precisely, for any d + 1 ≠ 2 (pseudo-) Riemannian manifold M with space-like or time-like boundary components, the BV data on the bulk induces compatible BFV data on the boundary. As a byproduct, the usual canonical formulation of general relativity is recovered in a straightforward way.

Einstein and a century of time

NASA Astrophysics Data System (ADS)

Raine, D. J.

2005-09-01

In a world overabundant in information, a subject is defined by its iconography. Physics is the falling apple, the planetary atom, the laser, the mushroom cloud and the image of the later Einstein - images that represent, respectively, gravity, atomic theory, quantum theory, mass-energy and the scientist who had a hand in all four. It is therefore appropriate that World Year of Physics is called Einstein Year in the UK. Of course one can argue that progress in science depends on the contributions of many people; that there are other geniuses in physics, even some colourful personalities. Nevertheless there are fundamental reasons why Einstein's early achievements stand out even in their company. When at last the thought came to him that 'time itself was suspect', Einstein had found a new insight into the nature of the physical universe. It is this: that the universal properties of material objects tell us about the nature of space and time, and it is through these properties, not philosophical logic or common sense, that we discover the structure of spacetime. The later Einstein turned this successful formula on its head and sought to use the properties of spacetime to define those of material objects, thereby seeking to abolish matter entirely in favour of geometry. Before I introduce this special feature of European Journal of Physics I will say a few words about what is not here. Like all great geniuses Einstein can be seen as the climax of what went before him and the initiation of what was to follow. Looking back we can see the influence of Mach's positivism, according to which the role of science is to relate observations to other observations; hence only observations can tell us what is 'real'. But Einstein also grew up with the family electromechanical businesses, which testifies to the reality of the Maxwellian electromagnetic fields: thus only theory can tell us what is real! As is well known, Einstein himself refused to accept the full consequences of this pivotal insight into the role of theory when it came to quantum mechanics. Much has been written about this and we do not add to it in this collection. Quantum theory is a consistent description of nature whatever Einstein may think of 'god' for making it so. Many of us would side with Einstein in hoping it will yet turn out not to be a complete description. This will not happen, as Einstein hoped throughout his later work, from a return to classical field theory. But quantum behaviour is a universal property of matter and may therefore be expected, according to Einstein's way of thought, to have a geometrical origin. The advent of non-commutative quantum geometries may turn out to be a step in this direction. My own introduction to Einstein's physics was through what has come to be known as Mach's principle. My research supervisor, Dennis Sciama, in what he always claimed was probably Einstein's last significant scientific conversation, talked with him on this subject, during which Einstein explained that he had abandoned the idea of Mach's principle. This principle had been a guiding thought in the development of general relativity, but superfluous to its final exposition. It can be interpreted variously as the determination of the local compass of inertia by the distant stars, the non-rotation of the Universe or, more restrictedly, as requiring a critical density universe (to generate the right amount of inertia). This last formulation amounts to Gρτ2 approx 1, where ρ is the density of the Universe at time τ. This appears to be a classical expression, which would probably be sufficient to relegate Mach's principle to mere historical interest along with the classical unified field theories. It is also usually considered to be accounted for by inflation, which drives the Universe to Ω=1. However, we can also think of the expression as saying that the Universe has a Planck mass in a Planck volume at the Planck time: G=(hc / G)1/2(c3 / Gh)3/2(Gh / c5)=1. This suggests that Mach's principle may yet have a surprising role in expressing the fact that the Universe contains sufficient matter to exist as a classical system: that is, that it contains sufficient material degrees of freedom to allow quantum decoherence to occur. It would at least be a nice irony if Mach's principle turned out to be a necessary quantum condition for the existence of a classical universe! Coming now to the papers in this special feature, these include several that treat historical aspects of relativity. Brown offers us a novel insight into Einstein's ambivalence about the status of special relativity in providing a mechanism for the contraction hypothesis. Trainer looks at the way in which Einstein presented a brief account of relativity in a lecture that he gave in Glasgow in 1933. Galvangno and Giribet look at Einstein's approach to the representation of particles within general relativity, or variants thereof, while Battimelli provides an account of attempts at unification of electromagnetism and relativity from the point of view of the origin of mass. In their contribution, Guerra and de Abreu look again at the relationship between the constancy of the speed of light and the nature of time that was central to Einstein's thinking. Next we come to a group of papers that look at educational issues. Einstein's equation E = mc2 is now iconic even if general knowledge quizzes that ask what the c stands for miss the entire point of the equation! Thomas starts from the way in which perceptions of relativity still focus on this equation as the essential ingredient of nuclear power and the need to disabuse even students of physics of this notion. He also looks at how we can in fact demonstrate the significance of the equation to a lay audience. I have added a short note on friction, another topic that confuses teachers and students alike, that throws up problems to which the solutions are contained in Einstein's Brownian motion paper. The Open University in the UK has been teaching relativity to distance-learners for forty years; Lambourne writes about the experience that has been gained. Finally, I have always been intrigued by the opprobrium that Einstein seems to attract from crank authors. I no longer regularly receive such nonsense to referee, I assume because the internet is now awash with 'publication' opportunities for anti-Einstein articles. I do believe however that the work of these authors throws light on the way science works and I have tried to illustrate this thesis briefly in the final paper of this collection.

General Relativity and Gravitation

NASA Astrophysics Data System (ADS)

Ehlers, J.; Murdin, P.

2000-11-01

The General Theory of Relativity (GR), created by Albert Einstein between 1907 and 1915, is a theory both of gravitation and of spacetime structure. It is based on the assumption that matter, via its energy-momentum, interacts with the metric of spacetime, which is considered (in contrast to Newtonian physics and SPECIAL RELATIVITY) as a dynamical field having degrees of freedom of its own (GRAVI...

What is general relativity?

NASA Astrophysics Data System (ADS)

Coley, Alan A.; Wiltshire, David L.

2017-05-01

General relativity is a set of physical and geometric principles, which lead to a set of (Einstein) field equations that determine the gravitational field and to the geodesic equations that describe light propagation and the motion of particles on the background. But open questions remain, including: what is the scale on which matter and geometry are dynamically coupled in the Einstein equations? Are the field equations valid on small and large scales? What is the largest scale on which matter can be coarse grained while following a geodesic of a solution to Einstein’s equations? We address these questions. If the field equations are causal evolution equations, whose average on cosmological scales is not an exact solution of the Einstein equations, then some simplifying physical principle is required to explain the statistical homogeneity of the late epoch Universe. Such a principle may have its origin in the dynamical coupling between matter and geometry at the quantum level in the early Universe. This possibility is hinted at by diverse approaches to quantum gravity which find a dynamical reduction to two effective dimensions at high energies on one hand, and by cosmological observations which are beginning to strongly restrict the class of viable inflationary phenomenologies on the other. We suggest that the foundational principles of general relativity will play a central role in reformulating the theory of spacetime structure to meet the challenges of cosmology in the 21st century.

On Einstein's Path, essays in honor of Engelbert Schucking

NASA Astrophysics Data System (ADS)

Harvey, Alex

This collection of essays in honor of Engelbert Schucking spans the gamut of research in general relativity and presents a lively and personal account of current work in the field. Contributions include: E.L. Schucking: Jordan, Pauli, Politics, Brecht... and a Variable Gravitational Constant J.L. Anderson: Thomson Scattering in an Expanding Universe A. Ashtekar & T.A. Schilling: Geometrical Formulation of Quantum Mechanics J. Baugh, D.R. Finkelstein, H. Saller, and Zhong Tang: General Covariance is Bose-Einstein Statistics S.L. Bazanski: The Split and Propagation of Light Rays in Relativity L. Bel: How to Define a Unique Vacuum in Cosmology P.G. Bergmann: EIH Theory and Noether's Theorem W.B. Bonnor: The Static Cylinder in General Relativity C.H. Brahns: Gravity and the Tenacious Scalar Field D. Brill: The Cavendish Experiment in General Relativity Y. Choquet-Bruhat: Wave Maps in General Relativity T. Damour: General Relativty and Experiment J. Ehlers: Some Developments in Newtonian Cosmology G.F.R. Ellis & H. van Elst: Deviation of Geodesics in FLRW Spacetime Geometries S. Frittelli & E.T. Newman: Poincar Pseudo-symmetries in Asymptotically Flat Spacetimes E.N. Glass: Taub Numbers and Asymptotic Invariants J.N. Goldberg: Second Class Constraints F.W. Hehl, A. Macias, E.W. Mielke, & Yu.N. Obukhov: On the Structure of the Energy-momentum and the Spin Currents in Dirac's Electron

Exact general relativistic disks with magnetic fields

NASA Astrophysics Data System (ADS)

Letelier, Patricio S.

1999-11-01

The well-known ``displace, cut, and reflect'' method used to generate cold disks from given solutions of Einstein equations is extended to solutions of Einstein-Maxwell equations. Four exact solutions of the these last equations are used to construct models of hot disks with surface density, azimuthal pressure, and azimuthal current. The solutions are closely related to Kerr, Taub-NUT, Lynden-Bell-Pinault, and to a one-soliton solution. We find that the presence of the magnetic field can change in a nontrivial way the different properties of the disks. In particular, the pure general relativistic instability studied by Bic̆ák, Lynden-Bell, and Katz [Phys. Rev. D 47, 4334 (1993)] can be enhanced or cured by different distributions of currents inside the disk. These currents, outside the disk, generate a variety of axial symmetric magnetic fields. As far as we know these are the first models of hot disks studied in the context of general relativity.

Rotating black holes in dilatonic Einstein-Gauss-Bonnet theory.

PubMed

Kleihaus, Burkhard; Kunz, Jutta; Radu, Eugen

2011-04-15

We construct generalizations of the Kerr black holes by including higher-curvature corrections in the form of the Gauss-Bonnet density coupled to the dilaton. We show that the domain of existence of these Einstein-Gauss-Bonnet-dilaton (EGBD) black holes is bounded by the Kerr black holes, the critical EGBD black holes, and the singular extremal EGBD solutions. The angular momentum of the EGBD black holes can exceed the Kerr bound. The EGBD black holes satisfy a generalized Smarr relation. We also compare their innermost stable circular orbits with those of the Kerr black holes and show the existence of differences which might be observable in astrophysical systems.

Dynamic wormhole solutions in Einstein-Cartan gravity

NASA Astrophysics Data System (ADS)

Mehdizadeh, Mohammad Reza; Ziaie, Amir Hadi

2017-12-01

In the present work, we investigate evolving wormhole configurations described by a constant redshift function in Einstein-Cartan theory. The matter content consists of a Weyssenhoff fluid along with an anisotropic matter which together generalize the anisotropic energy momentum tensor in general relativity in order to include the effects of intrinsic angular momentum (spin) of particles. Using a generalized Friedmann-Robertson-Walker spacetime, we derive analytical evolving wormhole geometries by assuming a particular equation of state for energy density and pressure profiles. We introduce exact asymptotically flat and anti-de Sitter spacetimes that admit traversable wormholes and respect energy conditions throughout the spacetime. The rate of expansion of these evolving wormholes is determined only by the Friedmann equation in the presence of spin effects.

The particle problem in classical gravity: a historical note on 1941

NASA Astrophysics Data System (ADS)

Galvagno, Mariano; Giribet, Gastón

2005-11-01

This historical note is mainly based on a relatively unknown paper published by Albert Einstein in Revista de la Universidad Nacional de Tucumán in 1941. Taking the ideas of this work as a leitmotiv, we review the discussions about the particle problem in the theory of gravitation within the historical context by means of the study of seminal works on the subject. The revision shows how the digressions regarding the structure of matter and the concise problem of finding regular solutions of the pure field equations turned out to be intrinsically unified in the beginning of the programme towards a final theory of fields. The paper mentioned (Einstein 1941a Rev. Univ. Nac. Tucumán A 2 11) represents the basis of the one written by Einstein in collaboration with Wolfgang Pauli in 1943, in which, following analogous lines, the proof of the non-existence of regular particle-type solutions was generalized to the case of cylindrical geometries in Kaluza-Klein theory (Einstein and Pauli 1943 Ann. Math. 44 131). Besides, other generalizations were subsequently presented. The (non-)existence of such solutions in classical unified field theory was undoubtedly an important criterion leading Einstein's investigations. This aspect was investigated with expertness by Jeroen van Dongen in a recent work, though restricting the scope to the particular case of Kaluza-Klein theory (van Dongen 2002 Stud. Hist. Phil. Mod. Phys. 33 185). Here, we discuss the particle problem within a more general context, presenting in this way a complement to previous reviews.

Merging Black Holes, Gravitational Waves, and Numerical Relativity

NASA Technical Reports Server (NTRS)

Centrella, Joan M.

2009-01-01

The final merger of two black holes will emit more energy than all the stars in the observable universe combined. This energy will come in the form of gravitational waves, which are a key prediction of Einstein's general relativity and a new tool for exploring the universe. Observing these mergers with gravitational wave detectors, such as the ground-based LIGO and the space-based LISA, requires knowledge of the radiation waveforms. Since these mergers take place in regions of extreme gravity, we need to solve Einstein's equations of general relativity on a computer. For more than 30 years, scientists have tried to compute black hole mergers using the methods of numerical relativity. The resulting computer codes were long plagued by instabilities, causing them to crash well before the black holes in the binary could complete even a single orbit. Within the past few years, however, this situation has changed dramatically, with a series of remarkable breakthroughs. This talk will focus on new simulations that are revealing the dynamics and w aefo rms of binary black hole mergers, and their applications in gravitational wave detection, testing general relativity, and astrophysics.

Generalized geometry and non-symmetric metric gravity

NASA Astrophysics Data System (ADS)

Jurčo, Branislav; Khoo, Fech Scen; Schupp, Peter; Vysoký, Jan

2016-04-01

Generalized geometry provides the framework for a systematic approach to non-symmetric metric gravity theory and naturally leads to an Einstein-Kalb-Ramond gravity theory with totally anti-symmetric contortion. The approach is related to the study of the low-energy effective closed string gravity actions.

The science, technology and mission design for the Laser Astrometric test of relativity

NASA Technical Reports Server (NTRS)

Turyshev, Slava G.

2006-01-01

The Laser Astrometric Test of Relativity (LATOR) is a Michelson-Morley-type experiment designed to test the Einstein's general theory of relativity in the most intense gravitational environment available in the solar system - the close proximity to the Sun.

A confirmation of the general relativistic prediction of the Lense-Thirring effect.

PubMed

Ciufolini, I; Pavlis, E C

2004-10-21

An important early prediction of Einstein's general relativity was the advance of the perihelion of Mercury's orbit, whose measurement provided one of the classical tests of Einstein's theory. The advance of the orbital point-of-closest-approach also applies to a binary pulsar system and to an Earth-orbiting satellite. General relativity also predicts that the rotation of a body like Earth will drag the local inertial frames of reference around it, which will affect the orbit of a satellite. This Lense-Thirring effect has hitherto not been detected with high accuracy, but its detection with an error of about 1 per cent is the main goal of Gravity Probe B--an ongoing space mission using orbiting gyroscopes. Here we report a measurement of the Lense-Thirring effect on two Earth satellites: it is 99 +/- 5 per cent of the value predicted by general relativity; the uncertainty of this measurement includes all known random and systematic errors, but we allow for a total +/- 10 per cent uncertainty to include underestimated and unknown sources of error.

q-deformed Einstein's model to describe specific heat of solid

NASA Astrophysics Data System (ADS)

Guha, Atanu; Das, Prasanta Kumar

2018-04-01

Realistic phenomena can be described more appropriately using generalized canonical ensemble, with proper parameter sets involved. We have generalized the Einstein's theory for specific heat of solid in Tsallis statistics, where the temperature fluctuation is introduced into the theory via the fluctuation parameter q. At low temperature the Einstein's curve of the specific heat in the nonextensive Tsallis scenario exactly lies on the experimental data points. Consequently this q-modified Einstein's curve is found to be overlapping with the one predicted by Debye. Considering only the temperature fluctuation effect(even without considering more than one mode of vibration is being triggered) we found that the CV vs T curve is as good as obtained by considering the different modes of vibration as suggested by Debye. Generalizing the Einstein's theory in Tsallis statistics we found that a unique value of the Einstein temperature θE along with a temperature dependent deformation parameter q(T) , can well describe the phenomena of specific heat of solid i.e. the theory is equivalent to Debye's theory with a temperature dependent θD.

S2 like Star Orbits near the Galactic Center in Rn and Yukawa Gravity

NASA Astrophysics Data System (ADS)

Borka, Dusko; Jovanović, Predrag; Jovanović Vesna Borka; Zakharov, Alexander F.

2015-01-01

In this chapter we investigate the possibility to provide theoretical explanation for the observed deviations of S2 star orbit around the Galactic Center using gravitational potentials derived from extended gravity models, but in absence of dark matter. Extended Theories of Gravity are alternative theories of gravitational interaction developed from the exact starting points investigated first by Einstein and Hilbert and aimed from one side to extend the positive results of General Relativity and, on the other hand, to cure its shortcomings. One of the aims of these theories is to explain galactic and extragalactic dynamics without introduction of dark matter. They are based on straightforward generalizations of the Einstein theory where the gravitational action (the Hilbert-Einstein action) is assumed to be linear in the Ricci curvature scalar R. The f(R) gravity is a type of modified gravity which generalizes Einstein's General Relativity, i.e. the simplest case is just the General Relativity. It is actually a family of models, each one defined by a different function of the Ricci scalar. Here, we consider Rn (power-law fourth-order theories of gravity) and Yukawa-like modified gravities in the weak field limit and discuss the constrains on these theories. For that purpose we simulate the orbit of S2 star around the Galactic Center in Rn and Yukawa-like gravity potentials and compare it with New Technology Telescope/Very Large Telescope (NTT/VLT) as well as by Keck telescope observations. Our simulations result in strong constraints on the range of gravity interaction and showed that both Rn and Yukawa gravity could satisfactorily explain the observed orbits of S2 star. However, we concluded that parameters of Rn and Yukawa gravity theories must be very close to those corresponding to the Newtonian limit of the theory. Besides, in contrast to Newtonian gravity, these two modified theories induce orbital precession, even in the case of point-like central mass. The approach we are proposing seems to be sufficiently reliable to constrain the modified gravity models from stellar orbits around Galactic Center.

Black hole dynamics in Einstein-Maxwell-dilaton theory

NASA Astrophysics Data System (ADS)

Hirschmann, Eric W.; Lehner, Luis; Liebling, Steven L.; Palenzuela, Carlos

2018-03-01

We consider the properties and dynamics of black holes within a family of alternative theories of gravity, namely Einstein-Maxwell-dilaton theory. We analyze the dynamical evolution of individual black holes as well as the merger of binary black hole systems. We do this for a wide range of parameter values for the family of Einstein-Maxwell-dilaton theories, investigating, in the process, the stability of these black holes. We examine radiative degrees of freedom, explore the impact of the scalar field on the dynamics of merger, and compare with other scalar-tensor theories. We argue that the dilaton can largely be discounted in understanding merging binary systems and that the end states essentially interpolate between charged and uncharged, rotating black holes. For the relatively small charge values considered here, we conclude that these black hole systems will be difficult to distinguish from their analogs within General Relativity.

Taming the nonlinearity of the Einstein equation.

PubMed

Harte, Abraham I

2014-12-31

Many of the technical complications associated with the general theory of relativity ultimately stem from the nonlinearity of Einstein's equation. It is shown here that an appropriate choice of dynamical variables may be used to eliminate all such nonlinearities beyond a particular order: Both Landau-Lifshitz and tetrad formulations of Einstein's equation are obtained that involve only finite products of the unknowns and their derivatives. Considerable additional simplifications arise in physically interesting cases where metrics become approximately Kerr or, e.g., plane waves, suggesting that the variables described here can be used to efficiently reformulate perturbation theory in a variety of contexts. In all cases, these variables are shown to have simple geometrical interpretations that directly relate the local causal structure associated with the metric of interest to the causal structure associated with a prescribed background. A new method to search for exact solutions is outlined as well.

General Motors sued for 'denigrating' Einstein's image

NASA Astrophysics Data System (ADS)

Gwynne, Peter

2010-07-01

The US car giant General Motors (GM) has played down the consequences of a lawsuit against it for using the likeness of Albert Einstein in an advertisement for its Terrain sports utility vehicle (SUV).

Towards thermodynamics of universal horizons in Einstein-æther theory.

PubMed

Berglund, Per; Bhattacharyya, Jishnu; Mattingly, David

2013-02-15

Holography grew out of black hole thermodynamics, which relies on the causal structure and general covariance of general relativity. In Einstein-æther theory, a generally covariant theory with a dynamical timelike unit vector, every solution breaks local Lorentz invariance, thereby grossly modifying the causal structure of gravity. However, there are still absolute causal boundaries, called "universal horizons," which are not Killing horizons yet obey a first law of black hole mechanics and must have an entropy if they do not violate a generalized second law. We couple a scalar field to the timelike vector and show via the tunneling approach that the universal horizon radiates as a blackbody at a fixed temperature, even if the scalar field equations also violate local Lorentz invariance. This suggests that the class of holographic theories may be much broader than currently assumed.

Why was Relativity Accepted?

NASA Astrophysics Data System (ADS)

Brush, S. G.

Historians of science have published many studies of the reception of Einstein's special and general theories of relativity. Based on a review of these studies, and my own research on the role of the light-bending prediction in the reception of general relativity, I discuss the role of three kinds of reasons for accepting relativity (1) empirical predictions and explanations; (2) social-psychological factors; and (3) aesthetic-mathematical factors. According to the historical studies, acceptance was a three-stage process. First, a few leading scientists adopted the special theory for aesthetic-mathematical reasons. In the second stage, their enthusiastic advocacy persuaded other scientists to work on the theory and apply it to problems currently of interest in atomic physics. The special theory was accepted by many German physicists by 1910 and had begun to attract some interest in other countries. In the third stage, the confirmation of Einstein's light-bending prediction attracted much public attention and forced all physicists to take the general theory of relativity seriously. In addition to light-bending, the explanation of the advance of Mercury's perihelion was considered strong evidence by theoretical physicists. The American astronomers who conducted successful tests of general relativity became defenders of the theory. There is little evidence that relativity was `socially constructed' but its initial acceptance was facilitated by the prestige and resources of its advocates.

The Einstein-Vlasov System/Kinetic Theory.

PubMed

Andréasson, Håkan

2005-01-01

The main purpose of this article is to provide a guide to theorems on global properties of solutions to the Einstein-Vlasov system. This system couples Einstein's equations to a kinetic matter model. Kinetic theory has been an important field of research during several decades in which the main focus has been on nonrelativistic and special relativistic physics, i.e. to model the dynamics of neutral gases, plasmas, and Newtonian self-gravitating systems. In 1990, Rendall and Rein initiated a mathematical study of the Einstein-Vlasov system. Since then many theorems on global properties of solutions to this system have been established. The Vlasov equation describes matter phenomenologically, and it should be stressed that most of the theorems presented in this article are not presently known for other such matter models (i.e. fluid models). This paper gives introductions to kinetic theory in non-curved spacetimes and then the Einstein-Vlasov system is introduced. We believe that a good understanding of kinetic theory in non-curved spacetimes is fundamental to good comprehension of kinetic theory in general relativity.

The Einstein-Vlasov System/Kinetic Theory.

PubMed

Andréasson, Håkan

2002-01-01

The main purpose of this article is to provide a guide to theorems on global properties of solutions to the Einstein-Vlasov system. This system couples Einstein's equations to a kinetic matter model. Kinetic theory has been an important field of research during several decades in which the main focus has been on nonrelativistic and special relativistic physics, i.e. to model the dynamics of neutral gases, plasmas, and Newtonian self-gravitating systems. In 1990, Rendall and Rein initiated a mathematical study of the Einstein-Vlasov system. Since then many theorems on global properties of solutions to this system have been established. The Vlasov equation describes matter phenomenologically, and it should be stressed that most of the theorems presented in this article are not presently known for other such matter models (i.e. fluid models). This paper gives introductions to kinetic theory in non-curved spacetimes and then the Einstein-Vlasov system is introduced. We believe that a good understanding of kinetic theory in non-curved spacetimes is fundamental to good comprehension of kinetic theory in general relativity.

BOOK REVIEW: Once Upon Einstein

NASA Astrophysics Data System (ADS)

Giannetto, E.

2007-07-01

Thibault Damour is a theoretical physicist, and a member of the French Academy of Sciences. This book is the translation, by Eric Novak, of the original French Si Einstein m'etait conté (Le Cherche Midi, 2005). It is neither a book of theoretical physics nor a biography of Einstein. It is not a book of history nor philosophy of science. In Damour's words it was written to encourage the reader to share with Einstein `those times when he understood some part of the hidden order of the universe'. It is a relatively short book, written in a very fluent style, but it deals with all the major problems and achievements of Einstein's works. Starting from special relativity, it continues with general relativity, quantum theories, unified field theory and a brief overview of the actual research related to Einstein's legacy. It is essentially a popular science book with some related exploration in history and philosophy to interpret physical theories. The most important problem discussed by Damour is the nature of time. On this subject, there is a very interesting short paragraph (pp 33--35) dedicated to the reception of the relativity idea by the great writer Marcel Proust and its counterpart within À la Recherche du Temps Perdu. A correct discussion of the implications of a relativistic time should imply the distinction of the different possible interpretations of this concept. Damour seems to conclude that only one interpretation is possible: `time does not exist', flowing of time is an illusion. One has to know that Einstein's ideas on time were related to Spinoza's perspective of a knowledge sub specie aeternitatis. However, other interpretations are possible and are related to the idea of time as an actuality. Damour speaks about the controversy between Einstein and Bergson, but Bergson is considered as a philosopher who did not understand relativity. This philosophical problem of relativistic time is indeed related to a historical problem briefly discussed by Damour (pp 17--21, 48--52 and related endnotes): had Henri Poincaré constructed a special relativistic dynamics before Einstein? There is a long debate on this subject in the literature. Damour's answer is negative and his conclusions seem related to the conservation of a myth of Einstein, that is, the rise of special relativity is considered as a creatio ex nihilo within Einstein's mind and Einstein is considered as the only genius able to conceive the relativity of time. Poincaré's texts are undervalued and misunderstood by Damour's cutting quotations from their context. Damour never quotes La Science et l'Hypothèse (1902): we know it was read by Einstein and here Poincaré first (within chapters already published as separate papers in 1900) stated the relativity of time and of simultaneity. Damour never quotes Poincaré's paper published on 5 June 1905, La dynamique de l'èlectron, which presents the first relativistic dynamics, invariant by Lorentz transformations. Poincaré's (July 1905) introduction of a quadrimensional space-time is considered by Damour only a mathematical artifice (p 51) and Damour never said that Minkowski took this idea from Poincaré! Poincaré's interpretation of relativistic time implies that it is not an illusion but a complex net of different real flows related to different processes. Poincaré and Einstein had different conceptions of Nature at the root of special relativity: respectively an electromagnetic conception (Poincaré) and a semi-mechanist one (Einstein). Thus, the (philosophical) meaning of relativity can be very different from the one presented by Damour. Furthermore, Damour accepts Kantian philosophy as a key to understanding relativity and quantum theories. This perspective seems to me very anachronistic and based on a misunderstanding: an interpretation of 20th century physical theories (relativity and quantum physics) is given within the framework of an 18th century philosophical perspective, created to give a foundation to Newton's theory. Relativity and quantum physics imply a breakdown of Kantian philosophy (see, for instance, G Bachelard's La Philosophie du Non). Relativity of space and time was considered possible only by overcoming the epistemological obstacle of Kantian idealistic foundation of Euclidean geometry and of Newton's absolute space and time. Relativity and quantum theories turn up not only the hierarchy between mathematics and physics, but also between epistemology (and logic) and physics: quantum physics implies not only a new conception of an indeterminate and unpredictable Nature, but a quantum logic too, that is, it implies a change in our way of thinking and knowing. When will the revolutionary impact of 20th century physics be reduced (by physicists themselves) to an already given philosophical framework?

Relativity in Transylvania and Patusan: Finding the roots of Einstein's theories of relativity in "Dracula" and "Lord Jim"

NASA Astrophysics Data System (ADS)

Tatum, Brian Shane

This thesis investigates the similarities in the study of time and space in literature and science during the modern period. Specifically, it focuses on the portrayal of time and space within Bram Stoker's Dracula (1897) and Joseph Conrad's Lord Jim (1899-1900), and compares the ideas presented with those later scientifically formulated by Albert Einstein in his special and general theories of relativity (1905-1915). Although both novels precede Einstein's theories, they reveal advanced complex ideas of time and space very similar to those later argued by the iconic physicist. These ideas follow a linear progression including a sense of temporal dissonance, the search for a communal sense of the present, the awareness and expansion of the individual's sense of the present, and the effect of mass on surrounding space. This approach enhances readings of Dracula and Lord Jim, illuminating the fascination with highly refined notions of time and space within modern European culture.

A modification of Einstein-Schrödinger theory that contains both general relativity and electrodynamics

NASA Astrophysics Data System (ADS)

Shifflett, J. A.

2008-08-01

We modify the Einstein-Schrödinger theory to include a cosmological constant Λ z which multiplies the symmetric metric, and we show how the theory can be easily coupled to additional fields. The cosmological constant Λ z is assumed to be nearly cancelled by Schrödinger’s cosmological constant Λ b which multiplies the nonsymmetric fundamental tensor, such that the total Λ = Λ z + Λ b matches measurement. The resulting theory becomes exactly Einstein-Maxwell theory in the limit as | Λ z | → ∞. For | Λ z | ~ 1/(Planck length)2 the field equations match the ordinary Einstein and Maxwell equations except for extra terms which are < 10-16 of the usual terms for worst-case field strengths and rates-of-change accessible to measurement. Additional fields can be included in the Lagrangian, and these fields may couple to the symmetric metric and the electromagnetic vector potential, just as in Einstein-Maxwell theory. The ordinary Lorentz force equation is obtained by taking the divergence of the Einstein equations when sources are included. The Einstein-Infeld-Hoffmann (EIH) equations of motion match the equations of motion for Einstein-Maxwell theory to Newtonian/Coulombian order, which proves the existence of a Lorentz force without requiring sources. This fixes a problem of the original Einstein-Schrödinger theory, which failed to predict a Lorentz force. An exact charged solution matches the Reissner-Nordström solution except for additional terms which are ~10-66 of the usual terms for worst-case radii accessible to measurement. An exact electromagnetic plane-wave solution is identical to its counterpart in Einstein-Maxwell theory.

Einstein contra Aristotle: The sound from the heavens

NASA Astrophysics Data System (ADS)

Neves, J. C. S.

2017-09-01

In "On the Heavens" Aristotle criticizes the Pythagorean point of view which claims the existence of a cosmic music and a cosmic sound. According to the Pythagorean argument, there exists a cosmic music produced by stars and planets. These celestial bodies generate sound in its movements, and the music appears due to the cosmic harmony. For Aristotle, there is no sound produced by celestial bodies. Then, there is no music as well. However, recently, LIGO (Laser Interferometer Gravitational-Waves Observatory) has detected the gravitational waves predicted by Einstein. In some sense, a sound originated from black holes has been heard. That is, Einstein or the General Relativity and LIGO appear to be with the Pythagoreanism and against the master of the Lyceum.

Quantum information and general relativity

NASA Astrophysics Data System (ADS)

Peres, A.

2004-11-01

The Einstein-Podolsky-Rosen paradox (1935) is reexamined in the light of Shannon's information theory (1948). The EPR argument did not take into account that the observers' information was localized, like any other physical object. General relativity introduces new problems: there are horizons which act as on-way membranes for the propagation of quantum information, in particular black holes which act like sinks.

Dark Energy, or Worse

ScienceCinema

Carroll, Sean

2018-01-09

General relativity is inconsistent with cosmological observations unless we invoke components of dark matter and dark energy that dominate the universe. While it seems likely that these exotic substances really do exist, the alternative is worth considering: that Einstein's general relativity breaks down on cosmological scales. I will discuss models of modified gravity, tests in the solar system and elsewhere, and consequences for cosmology.

Neutron stars in Horndeski gravity

NASA Astrophysics Data System (ADS)

Maselli, Andrea; Silva, Hector O.; Minamitsuji, Masato; Berti, Emanuele

2016-06-01

Horndeski's theory of gravity is the most general scalar-tensor theory with a single scalar whose equations of motion contain at most second-order derivatives. A subsector of Horndeski's theory known as "Fab Four" gravity allows for dynamical self-tuning of the quantum vacuum energy, and therefore it has received particular attention in cosmology as a possible alternative to the Λ CDM model. Here we study compact stars in Fab Four gravity, which includes as special cases general relativity ("George"), Einstein-dilaton-Gauss-Bonnet gravity ("Ringo"), theories with a nonminimal coupling with the Einstein tensor ("John"), and theories involving the double-dual of the Riemann tensor ("Paul"). We generalize and extend previous results in theories of the John class and were not able to find realistic compact stars in theories involving the Paul class.

Gravitation Theory: Empirical Status from Solar System Experiments: All observations to date are consistent with Einstein's general relativity theory of gravity.

PubMed

Nordtvedt, K L

1972-12-15

I have reviewed the historical and contemporary experiments that guide us in choosing a post-Newtonian, relativistic gravitational theory. The foundation experiments essentially constrain gravitation theory to be a metric theory in which matter couples solely to one gravitational field, the metric field, although other cosmological gravitational fields may exist. The metric field for any metric theory can be specified (for the solar system, for our present purposes) by a series of potential terms with several parameters. A variety of experiments specify (or put limits on) the numerical values of the seven parameters in the post-Newtonian metric field, and other such experiments have been planned. The empirical results, to date, yield values of the parameters that are consistent with the predictions of Einstein's general relativity.

Relativistic GLONASS and geodesy

NASA Astrophysics Data System (ADS)

Mazurova, E. M.; Kopeikin, S. M.; Karpik, A. P.

2016-12-01

GNSS technology is playing a major role in applications to civil, industrial and scientific areas. Nowadays, there are two fully functional GNSS: American GPS and Russian GLONASS. Their data processing algorithms have been historically based on the Newtonian theory of space and time with only a few relativistic effects taken into account as small corrections preventing the system from degradation on a fairly long time. Continuously growing accuracy of geodetic measurements and atomic clocks suggests reconsidering the overall approach to the GNSS theoretical model based on the Einstein theory of general relativity. This is essentially more challenging but fundamentally consistent theoretical approach to relativistic space geodesy. In this paper, we overview the basic principles of the relativistic GNSS model and explain the advantages of such a system for GLONASS and other positioning systems. Keywords: relativistic GLONASS, Einstein theory of general relativity.

Bardeen regular black hole with an electric source

NASA Astrophysics Data System (ADS)

Rodrigues, Manuel E.; Silva, Marcos V. de S.

2018-06-01

If some energy conditions on the stress-energy tensor are violated, is possible construct regular black holes in General Relativity and in alternative theories of gravity. This type of solution has horizons but does not present singularities. The first regular black hole was presented by Bardeen and can be obtained from Einstein equations in the presence of an electromagnetic field. E. Ayon-Beato and A. Garcia reinterpreted the Bardeen metric as a magnetic solution of General Relativity coupled to a nonlinear electrodynamics. In this work, we show that the Bardeen model may also be interpreted as a solution of Einstein equations in the presence of an electric source, whose electric field does not behave as a Coulomb field. We analyzed the asymptotic forms of the Lagrangian for the electric case and also analyzed the energy conditions.

Exact quantization of Einstein-Rosen waves coupled to massless scalar matter.

PubMed

Barbero G, J Fernando; Garay, Iñaki; Villaseñor, Eduardo J S

2005-07-29

We show in this Letter that gravity coupled to a massless scalar field with full cylindrical symmetry can be exactly quantized by an extension of the techniques used in the quantization of Einstein-Rosen waves. This system provides a useful test bed to discuss a number of issues in quantum general relativity, such as the emergence of the classical metric, microcausality, and large quantum gravity effects. It may also provide an appropriate framework to study gravitational critical phenomena from a quantum point of view, issues related to black hole evaporation, and the consistent definition of test fields and particles in quantum gravity.

Stochastic quantization of (λϕ4)d scalar theory: Generalized Langevin equation with memory kernel

NASA Astrophysics Data System (ADS)

Menezes, G.; Svaiter, N. F.

2007-02-01

The method of stochastic quantization for a scalar field theory is reviewed. A brief survey for the case of self-interacting scalar field, implementing the stochastic perturbation theory up to the one-loop level, is presented. Then, it is introduced a colored random noise in the Einstein's relations, a common prescription employed by one of the stochastic regularizations, to control the ultraviolet divergences of the theory. This formalism is extended to the case where a Langevin equation with a memory kernel is used. It is shown that, maintaining the Einstein's relations with a colored noise, there is convergence to a non-regularized theory.

A microscopic model of the Stokes-Einstein relation in arbitrary dimension.

PubMed

Charbonneau, Benoit; Charbonneau, Patrick; Szamel, Grzegorz

2018-06-14

The Stokes-Einstein relation (SER) is one of the most robust and widely employed results from the theory of liquids. Yet sizable deviations can be observed for self-solvation, which cannot be explained by the standard hydrodynamic derivation. Here, we revisit the work of Masters and Madden [J. Chem. Phys. 74, 2450-2459 (1981)], who first solved a statistical mechanics model of the SER using the projection operator formalism. By generalizing their analysis to all spatial dimensions and to partially structured solvents, we identify a potential microscopic origin of some of these deviations. We also reproduce the SER-like result from the exact dynamics of infinite-dimensional fluids.

New variables for classical and quantum gravity

NASA Technical Reports Server (NTRS)

Ashtekar, Abhay

1986-01-01

A Hamiltonian formulation of general relativity based on certain spinorial variables is introduced. These variables simplify the constraints of general relativity considerably and enable one to imbed the constraint surface in the phase space of Einstein's theory into that of Yang-Mills theory. The imbedding suggests new ways of attacking a number of problems in both classical and quantum gravity. Some illustrative applications are discussed.

Finding Horndeski theories with Einstein gravity limits

DOE Office of Scientific and Technical Information (OSTI.GOV)

McManus, Ryan; Lombriser, Lucas; Peñarrubia, Jorge, E-mail: ryanm@roe.ac.uk, E-mail: llo@roe.ac.uk, E-mail: jorpega@roe.ac.uk

The Horndeski action is the most general scalar-tensor theory with at most second-order derivatives in the equations of motion, thus evading Ostrogradsky instabilities and making it of interest when modifying gravity at large scales. To pass local tests of gravity, these modifications predominantly rely on nonlinear screening mechanisms that recover Einstein's Theory of General Relativity in regions of high density. We derive a set of conditions on the four free functions of the Horndeski action that examine whether a specific model embedded in the action possesses an Einstein gravity limit or not. For this purpose, we develop a new andmore » surprisingly simple scaling method that identifies dominant terms in the equations of motion by considering formal limits of the couplings that enter through the new terms in the modified action. This enables us to find regimes where nonlinear terms dominate and Einstein's field equations are recovered to leading order. Together with an efficient approximation of the scalar field profile, one can then further evaluate whether these limits can be attributed to a genuine screening effect. For illustration, we apply the analysis to both a cubic galileon and a chameleon model as well as to Brans-Dicke theory. Finally, we emphasise that the scaling method also provides a natural approach for performing post-Newtonian expansions in screened regimes.« less

Outer boundary as arrested history in general relativity

NASA Astrophysics Data System (ADS)

Lau, Stephen R.

2002-06-01

We present explicit outer boundary conditions for the canonical variables of general relativity. The conditions are associated with the causal evolution of a finite Cauchy domain, a so-called quasilocal boost, and they suggest a consistent scheme for modelling such an evolution numerically. The scheme involves a continuous boost in the spacetime orthogonal complement ⊥Tp(B) of the tangent space Tp(B) belonging to each point p on the system boundary B. We show how the boost rate may be computed numerically via equations similar to those appearing in canonical investigations of black-hole thermodynamics (although here holding at an outer two-surface rather than the bifurcate two-surface of a Killing horizon). We demonstrate the numerical scheme on a model example, the quasilocal boost of a spherical three-ball in Minkowski spacetime. Developing our general formalism with recent hyperbolic formulations of the Einstein equations in mind, we use Anderson and York's 'Einstein-Christoffel' hyperbolic system as the evolution equations for our numerical simulation of the model.

Antigravity Acts on Photons

NASA Astrophysics Data System (ADS)

Brynjolfsson, Ari

2002-04-01

Einstein's general theory of relativity assumes that photons don't change frequency as they move from Sun to Earth. This assumption is correct in classical physics. All experiments proving the general relativity are in the domain of classical physics. This include the tests by Pound et al. of the gravitational redshift of 14.4 keV photons; the rocket experiments by Vessot et al.; the Galileo solar redshift experiments by Krisher et al.; the gravitational deflection of light experiments by Riveros and Vucetich; and delay of echoes of radar signals passing close to Sun as observed by Shapiro et al. Bohr's correspondence principle assures that quantum mechanical theory of general relativity agrees with Einstein's classical theory when frequency and gravitational field gradient approach zero, or when photons cannot interact with the gravitational field. When we treat photons as quantum mechanical particles; we find that gravitational force on photons is reversed (antigravity). This modified theory contradicts the equivalence principle, but is consistent with all experiments. Solar lines and distant stars are redshifted in accordance with author's plasma redshift theory. These changes result in a beautiful consistent cosmology.

Cerebral cortex astroglia and the brain of a genius: A propos of A. Einstein's

PubMed Central

Colombo, Jorge A.; Reisin, Hernán D.; Miguel-Hidalgo, José J.; Rajkowska, Grazyna

2010-01-01

The glial fibrillary acidic protein immunoreactive astroglial layout of the cerebral cortex from Albert Einstein and other four age-matched human cases lacking any known neurological disease was analyzed using quantification of geometrical features mathematically defined. Several parameters (parallelism, relative depth, tortuosity) describing the primate-specific interlaminar glial processes did not show individually distinctive characteristics in any of the samples analyzed. However, A. Einstein's astrocytic processes showed larger sizes and higher numbers of interlaminar terminal masses, reaching sizes of 15 μm in diameter. These bulbous endings are of unknown significance and they have been described occurring in Alzheimer's disease. These observations are placed in the context of the general discussion regarding the proposal – by other authors – that structural, postmortem characteristics of the aged brain of Albert Einstein may serve as markers of his cognitive performance, a proposal to which the authors of this paper do not subscribe, and argue against. PMID:16675021

Inevitable inflation in Einstein-Cartan theory with improved energy-momentum tensor with spin

NASA Technical Reports Server (NTRS)

Fennelly, A. J.; Bradas, James C.; Smalley, Larry L.

1988-01-01

Generalized, or power-law, inflation is shown to necessarily exist for a simple, anisotropic, (Bianchi Type-1) cosmology in the Einstein-Cartan gravitational theory with the Ray-Smalley improved energy momentum tensor with spin. Formal solution of the EC field equations with the fluid equations of motion explicitly shows inflation caused by the RS spin angular kinetic energy density. Shear is not effective in preventing inflation in the ECRS model. The relation between fluid vorticity, torsion, reference axis rotation, and shear ellipsoid precession shows through clearly.

Schwarzschild Solution: A Historical Perspective

NASA Astrophysics Data System (ADS)

Bartusiak, Marcia

2016-03-01

While eighteenth-century Newtonians had imagined a precursor to the black hole, the modern version has its roots in the first full solution to Einstein's equations of general relativity, derived by the German astronomer Karl Schwarzschild on a World War I battlefront just weeks after Einstein introduced his completed theory in November 1915. This talk will demonstrate how Schwarzschild's solution is linked to the black hole and how it took more than half a century for the physics community to accept that such a bizarre celestial object could exist in the universe.

Nonsingular solutions and instabilities in Einstein-scalar-Gauss-Bonnet cosmology

NASA Astrophysics Data System (ADS)

Sberna, Laura; Pani, Paolo

2017-12-01

It is generically believed that higher-order curvature corrections to the Einstein-Hilbert action might cure the curvature singularities that plague general relativity. Here we consider Einstein-scalar-Gauss-Bonnet gravity, the only four-dimensional, ghost-free theory with quadratic curvature terms. For any choice of the coupling function and of the scalar potential, we show that the theory does not allow for bouncing solutions in the flat and open Friedmann universe. For the case of a closed universe, using a reverse-engineering method, we explicitly provide a bouncing solution which is nevertheless linearly unstable in the scalar gravitational sector. Moreover, we show that the expanding, singularity-free, early-time cosmologies allowed in the theory are unstable. These results rely only on analyticity and finiteness of cosmological variables at early times.

Twistor-strings and gravity tree amplitudes

NASA Astrophysics Data System (ADS)

Adamo, Tim; Mason, Lionel

2013-04-01

Recently we discussed how Einstein supergravity tree amplitudes might be obtained from the original Witten and Berkovits twistor-string theory when external conformal gravitons are restricted to be Einstein gravitons. Here we obtain a more systematic understanding of the relationship between conformal and Einstein gravity amplitudes in that twistor-string theory. We show that although it does not in general yield Einstein amplitudes, we can nevertheless obtain some partial twistor-string interpretation of the remarkable formulae recently been found by Hodges and generalized to all tree amplitudes by Cachazo and Skinner. The Hodges matrix and its higher degree generalizations encode the world sheet correlators of the twistor string. These matrices control both Einstein amplitudes and those of the conformal gravity arising from the Witten and Berkovits twistor-string. Amplitudes in the latter case arise from products of the diagonal elements of the generalized Hodges matrices and reduced determinants give the former. The reduced determinants arise if the contractions in the worldsheet correlator are restricted to form connected trees at MHV. The (generalized) Hodges matrices arise as weighted Laplacian matrices for the graph of possible contractions in the correlators and the reduced determinants of these weighted Laplacian matrices give the sum of the connected tree contributions by an extension of the matrix-tree theorem.

The Redshifts in Relativity

ERIC Educational Resources Information Center

Singh, Satya Pal; Singh, Apoorva; Hareet, Prabhav

2011-01-01

The progress of modern cosmology took off in 1917 when A. Einstein published his paper on general theory of relativity extending his work of special theory of relativity (1905). In 1922 Alexander Friedmann constructed a mathematical model for expanding Universe that had a big bang in remote past. The experimental evidences could come in 1929 by…

The rotational motion of an earth orbiting gyroscope according to the Einstein theory of general relativity

NASA Technical Reports Server (NTRS)

Hoots, F. R.; Fitzpatrick, P. M.

1979-01-01

The classical Poisson equations of rotational motion are used to study the attitude motions of an earth orbiting, rapidly spinning gyroscope perturbed by the effects of general relativity (Einstein theory). The center of mass of the gyroscope is assumed to move about a rotating oblate earth in an evolving elliptic orbit which includes all first-order oblateness effects produced by the earth. A method of averaging is used to obtain a transformation of variables, for the nonresonance case, which significantly simplifies the Poisson differential equations of motion of the gyroscope. Long-term solutions are obtained by an exact analytical integration of the simplified transformed equations. These solutions may be used to predict both the orientation of the gyroscope and the motion of its rotational angular momentum vector as viewed from its center of mass. The results are valid for all eccentricities and all inclinations not near the critical inclination.

Tikekar superdense stars in electric fields

NASA Astrophysics Data System (ADS)

Komathiraj, K.; Maharaj, S. D.

2007-04-01

We present exact solutions to the Einstein-Maxwell system of equations with a specified form of the electric field intensity by assuming that the hypersurface {t=constant} are spheroidal. The solution of the Einstein-Maxwell system is reduced to a recurrence relation with variable rational coefficients which can be solved in general using mathematical induction. New classes of solutions of linearly independent functions are obtained by restricting the spheroidal parameter K and the electric field intensity parameter α. Consequently, it is possible to find exact solutions in terms of elementary functions, namely, polynomials and algebraic functions. Our result contains models found previously including the superdense Tikekar neutron star model [J. Math. Phys. 31, 2454 (1990)] when K=-7 and α=0. Our class of charged spheroidal models generalize the uncharged isotropic Maharaj and Leach solutions [J. Math. Phys. 37, 430 (1996)]. In particular, we find an explicit relationship directly relating the spheroidal parameter K to the electromagnetic field.

Republication of: Geometrodynamics in the null case. Exact solutions of the field equations of the general theory of relativity III

NASA Astrophysics Data System (ADS)

Jordan, Pascual; Kundt, Wolfgang

2014-03-01

This is an English translation of a paper by Pascual Jordan and Wolfgang Kundt, first published in 1961 in the proceedings of the Academy of Sciences and Literature in Mainz (Germany). The original paper was part 3 of a five-part series of articles containing the first summary of knowledge about exact solutions of Einstein's equations found until then. (Parts 1, 2 and 4 of the series have already been reprinted, part 5 will be printed as a Golden Oldie in near future.) This third paper shows how solutions of the Einstein-Maxwell equations with null Maxwell field can be incorporated into the scheme of geometrodynamics. It has been selected by the Editors of General Relativity and Gravitation for republication in the Golden Oldies series of the journal. The republication is accompanied by an editorial note written by Charles Misner.

Mass Function of Galaxy Clusters in Relativistic Inhomogeneous Cosmology

NASA Astrophysics Data System (ADS)

Ostrowski, Jan J.; Buchert, Thomas; Roukema, Boudewijn F.

The current cosmological model (ΛCDM) with the underlying FLRW metric relies on the assumption of local isotropy, hence homogeneity of the Universe. Difficulties arise when one attempts to justify this model as an average description of the Universe from first principles of general relativity, since in general, the Einstein tensor built from the averaged metric is not equal to the averaged stress-energy tensor. In this context, the discrepancy between these quantities is called "cosmological backreaction" and has been the subject of scientific debate among cosmologists and relativists for more than 20 years. Here we present one of the methods to tackle this problem, i.e. averaging the scalar parts of the Einstein equations, together with its application, the cosmological mass function of galaxy clusters.

The NASA Beyond Einstein Program

NASA Technical Reports Server (NTRS)

White, Nicholas E.

2006-01-01

Einstein's legacy is incomplete, his theory of General relativity raises -- but cannot answer --three profound questions: What powered the big bang? What happens to space, time, and matter at the edge of a black hole? and What is the mysterious dark energy pulling the Universe apart? The Beyond Einstein program within NASA's Office of Space Science aims to answer these questions, employing a series of missions linked by powerful new technologies and complementary approaches towards shared science goals. The Beyond Einstein program has three linked elements which advance science and technology towards two visions; to detect directly gravitational wave signals from the earliest possible moments of the BIg Bang, and to image the event horizon of a black hole. The central element is a pair of Einstein Great Observatories, Constellation-X and LISA. Constellation-X is a powerful new X-ray observatory dedicated to X-Ray Spectroscopy. LISA is the first spaced based gravitational wave detector. These powerful facilities will blaze new paths to the questions about black holes, the Big Bang and dark energy. The second element is a series of competitively selected Einstein Probes, each focused on one of the science questions and includes a mission dedicated resolving the Dark Energy mystery. The third element is a program of technology development, theoretical studies and education. The Beyond Einstein program is a new element in the proposed NASA budget for 2004. This talk will give an overview of the program and the missions contained within it.

Einstein and Einstein A: A Study in Crater Morphology

NASA Image and Video Library

2017-12-08

NASA image release May 14, 2010 Einstein and Einstein A: A Study in Crater Morphology Located on the western limb of the Moon, Einstein and Einstein A craters (16.3oN, 271.3oE ) are only visible to Earth-based observers during certain lunar lighting and orientation conditions. Einstein A is younger than Einstein, as indicated by the fact that it lies squarely in the middle of the floor of Einstein. When viewed in topographic data, these two craters reveal much about the relative age and shape of an impact crater. To understand further, let's first take a look at Einstein. Einstein is a fairly large crater that spans 198 km across. A crater's size alone however cannot reveal much about age. ÊEinstein's relative age can be determined by examining the frequency and distribution of impact craters overprinted on its rim and floor. Younger craters have had fewer impacts, which enables them to retain their original morphology. Einstein A reveals most of its original structure, including a raised rim and ejecta blanket, and is therefore a relatively young crater as compared to Einstein, whose original structure has been somewhat degraded over time by smaller impacts. The Einstein craters were named after famed physicist, philosopher, and scientist Albert Einstein (1879-1955). To learn more go to: www.nasa.gov/mission_pages/LRO/multimedia/lroimages/lola-... NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

Gravitational Physics: the birth of a new era

NASA Astrophysics Data System (ADS)

Sakellariadou, Mairi

2017-11-01

We live the golden age of cosmology, while the era of gravitational astronomy has finally begun. Still, fundamental puzzles remain. Standard cosmology is formulated within the framework of Einstein's General theory of Relativity. Notwithstanding, General Relativity is not adequate to explain the earliest stages of cosmic existence, and cannot provide an explanation for the Big Bang itself. Modern early universe cosmology is in need of a rigorous underpinning in Quantum Gravity.

The Gravity Probe B Experiment

NASA Technical Reports Server (NTRS)

Kolodziejczak, Jeffrey

2008-01-01

This presentation briefly describes the Gravity Probe B (GP-B) Experiment which is designed to measure parts of Einstein's general theory of relativity by monitoring gyroscope orientation relative to a distant guide star. To measure the miniscule angles predicted by Einstein's theory, it was necessary to build near-perfect gyroscopes that were approximately 50 million times more precise than the best navigational gyroscopes. A telescope mounted along the central axis of the dewar and spacecraft provided the experiment's pointing reference to a guide star. The telescope's image divide precisely split the star's beam into x-axis and y-axis components whose brightness could be compared. GP-B's 650-gallon dewar, kept the science instrument inside the probe at a cryogenic temperature for 17.3 months and also provided the thruster propellant for precision attitude and translation control. Built around the dewar, the GP-B spacecraft was a total-integrated system, comprising both the space vehicle and payload, dedicated as a single entity to experimentally testing predictions of Einstein's theory.

On the Correct Formulation of the Law of the External Photoelectric Effect

NASA Astrophysics Data System (ADS)

Kalanov, Temur Z.

2017-01-01

The critical and correct scientific analysis of the generally accepted theory of the external photoelectric effect is proposed. The methodological basis for the analysis is the unity of formal logic and of rational dialectics. It is shown that Einstein's formulation of the law of the photoelectric effect is not free from the following objection. The terms of Einstein's formula characterize the quantitative determinacy (i.e., energy) which belongs and is related to the different material objects: ``photon'', ``electron in metal'', and ``electron not in metal''. This signifies that Einstein's formula represents violation of the formal-logical laws of identity and absence (lack) of contradiction. The correct mathematical formulation of the law of the external photoelectric effect within the framework of the system approach is proposed. The correct formulation represents the proportion by relative increments of the energy of the incident photon and the energy of the emitted electron. The proportion describes the linear relationship between the energy of the incident photon and the energy of the emitted electron.

Implications of a positive cosmological constant for general relativity.

PubMed

Ashtekar, Abhay

2017-10-01

Most of the literature on general relativity over the last century assumes that the cosmological constant [Formula: see text] is zero. However, by now independent observations have led to a consensus that the dynamics of the universe is best described by Einstein's equations with a small but positive [Formula: see text]. Interestingly, this requires a drastic revision of conceptual frameworks commonly used in general relativity, no matter how small [Formula: see text] is. We first explain why, and then summarize the current status of generalizations of these frameworks to include a positive [Formula: see text], focusing on gravitational waves.

The absence of gravitational waves and the foundations of Relativistic Cosmology

NASA Astrophysics Data System (ADS)

Djidjian, Robert

2015-07-01

Modern relativistic cosmology is based on Albert Einstein's teaching of general relativity. Observational and experimental impressive verification of general relativity have created among the astrophysicists the conviction that general relativity and relativistic cosmology are absolutely true theories. Unfortunately, the most important conclusion of general relativity is that the necessary existence of gravitational waves has been rejected by all the experiments up to the present time. There is also a kind of direct objection to the conception of expanding Universe: with the expansion of space identically expands the measuring stick, which makes the distances between the galaxies unchanged. So it should be quite reasonable to open discussions regarding the status of both general relativity and relativistic cosmology.

Gravitational Lensing: Einstein's unfinished symphony

NASA Astrophysics Data System (ADS)

Treu, Tommaso; Ellis, Richard S.

2015-01-01

Gravitational lensing - the deflection of light rays by gravitating matter - has become a major tool in the armoury of the modern cosmologist. Proposed nearly a hundred years ago as a key feature of Einstein's theory of general relativity, we trace the historical development since its verification at a solar eclipse in 1919. Einstein was apparently cautious about its practical utility and the subject lay dormant observationally for nearly 60 years. Nonetheless there has been rapid progress over the past twenty years. The technique allows astronomers to chart the distribution of dark matter on large and small scales thereby testing predictions of the standard cosmological model which assumes dark matter comprises a massive weakly-interacting particle. By measuring the distances and tracing the growth of dark matter structure over cosmic time, gravitational lensing also holds great promise in determining whether the dark energy, postulated to explain the accelerated cosmic expansion, is a vacuum energy density or a failure of general relativity on large scales. We illustrate the wide range of applications which harness the power of gravitational lensing, from searches for the earliest galaxies magnified by massive clusters to those for extrasolar planets which temporarily brighten a background star. We summarise the future prospects with dedicated ground and space-based facilities designed to exploit this remarkable physical phenomenon.

Bridging the knowledge gap: An analysis of Albert Einstein's popularized presentation of the equivalence of mass and energy.

PubMed

Kapon, Shulamit

2014-11-01

This article presents an analysis of a scientific article written by Albert Einstein in 1946 for the general public that explains the equivalence of mass and energy and discusses the implications of this principle. It is argued that an intelligent popularization of many advanced ideas in physics requires more than the simple elimination of mathematical formalisms and complicated scientific conceptions. Rather, it is shown that Einstein developed an alternative argument for the general public that bypasses the core of the formal derivation of the equivalence of mass and energy to provide a sense of derivation based on the history of science and the nature of scientific inquiry. This alternative argument is supported and enhanced by variety of explanatory devices orchestrated to coherently support and promote the reader's understanding. The discussion centers on comparisons to other scientific expositions written by Einstein for the general public. © The Author(s) 2013.

Gravitational waves in Einstein-æther and generalized TeVeS theory after GW170817

NASA Astrophysics Data System (ADS)

Gong, Yungui; Hou, Shaoqi; Liang, Dicong; Papantonopoulos, Eleftherios

2018-04-01

In this work we discuss the polarization contents of Einstein-æther theory and the generalized tensor-vector-scalar (TeVeS) theory, as both theories have a normalized timelike vector field. We derive the linearized equations of motion around the flat spacetime background using the gauge-invariant variables to easily separate physical degrees of freedom. We find the plane wave solutions and identify the polarizations by examining the geodesic deviation equations. We find that there are five polarizations in Einstein-æther theory and six polarizations in the generalized TeVeS theory. In particular, the transverse breathing mode is mixed with the pure longitudinal mode. We also discuss the experimental tests of the extra polarizations in Einstein-æther theory using pulsar timing arrays combined with the gravitational-wave speed bound derived from the observations on GW 170817 and GRB 170817A. It turns out that it might be difficult to use pulsar timing arrays to distinguish different polarizations in Einstein-æther theory. The same speed bound also forces one of the propagating modes in the generalized TeVeS theory to travel much faster than the speed of light. Since the strong coupling problem does not exist in some parameter subspaces, the generalized TeVeS theory is excluded in these parameter subspaces.

Reconstruction of the History of the Photoelectric Effect and Its Implications for General Physics Textbooks

ERIC Educational Resources Information Center

Niaz, Mansoor; Klassen, Stephen; McMillan, Barbara; Metz, Don

2010-01-01

The photoelectric effect is an important part of general physics textbooks. To study the presentation of this phenomenon, we have reconstructed six essential, history and philosophy of science (HPS)-related aspects of the events that culminated in Einstein proposing his hypothesis of lightquanta and the ensuing controversy within the scientific…

Optical design for the Laser Astrometric Test of Relativity

NASA Technical Reports Server (NTRS)

Turyshev, Slava G.; Shao, Michael; Nordtvedt, Kenneth L., Jr.

2004-01-01

This paper discusses the Laser Astrometric Test of Relativity (LATOR) mission. LATOR is a Michelson-Morley-type experiment designed to test the pure tensor metric nature of gravitation the fundamental postulate of Einstein's theory of general relativity. With its focus on gravity's action on light propagation it complements other tests which rely on the gravitational dynamics of bodies.

Numerical Relativity

NASA Technical Reports Server (NTRS)

Baker, John G.

2009-01-01

Recent advances in numerical relativity have fueled an explosion of progress in understanding the predictions of Einstein's theory of gravity, General Relativity, for the strong field dynamics, the gravitational radiation wave forms, and consequently the state of the remnant produced from the merger of compact binary objects. I will review recent results from the field, focusing on mergers of two black holes.

Stability of the Einstein static universe in open cosmological models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Canonico, Rosangela; Parisi, Luca; INFN, Sezione di Napoli, GC di Salerno, Via Ponte Don Melillo, I-84081 Baronissi

2010-09-15

The stability properties of the Einstein static solution of general relativity are altered when corrective terms arising from modification of the underlying gravitational theory appear in the cosmological equations. In this paper the existence and stability of static solutions are considered in the framework of two recently proposed quantum gravity models. The previously known analysis of the Einstein static solutions in the semiclassical regime of loop quantum cosmology with modifications to the gravitational sector is extended to open cosmological models where a static neutrally stable solution is found. A similar analysis is also performed in the framework of Horava-Lifshitz gravitymore » under detailed balance and projectability conditions. In the case of open cosmological models the two solutions found can be either unstable or neutrally stable according to the admitted values of the parameters.« less

BOOK REVIEW: The Legacy of Albert Einstein: A Collection of Essays in Celebration of the Year of Physics

NASA Astrophysics Data System (ADS)

Straumann, Norbert

2007-10-01

During the 'World Year of Physics' much has been written on the epoch-making 1905 papers of Albert Einstein and his later great contributions to physics. Why another book on the enormous impact of Einstein's work on 20th-century physics? The short answer is that the present collection of 13 relatively short essays on the legacy of Einstein by outstanding scientists is very pleasant to read and should be of interest to physicists of all branches. Beside looking back, most articles present later and topical developments, whose initiation began with the work of Einstein. During the year 2005, the growing recognition among physicists, historians, and philosophers of Einstein's revolutionary role in quantum theory was often emphasized. It is truly astonishing that most active physicists were largely unaware of this before. Fortunately, the article 'Einstein and the quantum' by V Singh puts the subject in perspective and describes all the main steps, beginning with the truly revolutionary 1905 paper on the light-quantum hypothesis and ending with Einstein's extension of the particle-wave duality to atoms and other particles in 1924 1925. The only point which, in my opinion, is not sufficiently emphasized in the discussion of the 1916 1917 papers on absorption and emission of radiation is the part on the momentum transfer in each elementary process. Einstein's result that there is a directed recoil hν/c—also for spontaneous emission—in complete contrast to classical theory, was particularly important to him. I enjoyed reading the articles on Brownian motion (S Majumdar), Bose Einstein condensation (N Kumar) and strongly correlated electrons (T Ramakrishnan), which are all written for non-experts. Connected with Einstein's most lasting work—general relativity—there are two articles on cosmology. The one by J Narlikar gives a brief historical account of the development that was initiated by the 1917 paper of Einstein. S Sarkar's essay emphasizes the remarkable recent observational progress in cosmology and the emergence of the 'cosmic concordance model', with dark matter and dark energy as the dominant components of the current universe. Their discovery is widely considered as the most direct evidence for fundamental physics beyond the standard model of particle physics. In an introductory section Sarkar recalls the main reasons why the cosmological constant (vacuum energy) problem is of a very profound nature. In spite of some interesting ideas, no satisfactory solution is in sight. The article by B Sathyapakhash on gravitational radiation provides a readable introduction to the status of current detectors and astronomical sources of gravitational radiation. Of great cosmological interest are planned searches for a stochastic background of gravitational waves that is expected to have been produced by quantum processes in the very early universe. More than the first third of the book is devoted to current speculative attempts at creating a quantum theory of gravity, possibly within a unified coherent description of the known four fundamental interactions. Thanks to the enormously large value of the Planck energy in comparison to elementary particle masses, physicists may maintain for a long time, with success, a schizophrenic attitude in working within the framework of our present understanding, based on quantum field theory and classical general relativity. That physics cannot stay with that was already pointed out by Einstein in 1916, as A Ashtekar recalls in his essay. 'Einstein and the search for unification' by D Gross is the first article of the present book. In this he describes the reasons why, for those working in speculative areas, 'Einstein remains an inspiration for his foresight, and his unyielding determination and courage'. This inspiration is also manifest in the essays by M Atiyah, A Sen, and A Dabholkar on string theory. Hopefully, this book will find many readers, especially among graduate students, who can get valuable impressions of what is interesting in physics and what some of the main open problems for future research are.

Thermodynamic properties of charged three-dimensional black holes in the scalar-tensor gravity theory

NASA Astrophysics Data System (ADS)

Dehghani, M.

2018-02-01

Making use of the suitable transformation relations, the action of three-dimensional Einstein-Maxwell-dilaton gravity theory has been obtained from that of scalar-tensor modified gravity theory coupled to the Maxwell's electrodynamics as the matter field. Two new classes of the static three-dimensional charged dilatonic black holes, as the exact solutions to the coupled scalar, electromagnetic and gravitational field equations, have been obtained in the Einstein frame. Also, it has been found that the scalar potential can be written in the form of a generalized Liouville-type potential. The conserved black hole charge and masses as well as the black entropy, temperature, and electric potential have been calculated from the geometrical and thermodynamical approaches, separately. Through comparison of the results arisen from these two alternative approaches, the validity of the thermodynamical first law has been proved for both of the new black hole solutions in the Einstein frame. Making use of the canonical ensemble method, a black hole stability or phase transition analysis has been performed. Regarding the black hole heat capacity, with the black hole charge as a constant, the points of type-1 and type-2 phase transitions have been determined. Also, the ranges of the black hole horizon radius at which the Einstein black holes are thermally stable have been obtained for both of the new black hole solutions. Then making use of the inverse transformation relations, two new classes of the string black hole solutions have been obtained from their Einstein counterpart. The thermodynamics and thermal stability of the new string black hole solutions have been investigated. It has been found that thermodynamic properties of the new charged black holes are identical in the Einstein and Jordan frames.

General very special relativity in Finsler cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kouretsis, A. P.; Stathakopoulos, M.; Stavrinos, P. C.

2009-05-15

General very special relativity (GVSR) is the curved space-time of very special relativity (VSR) proposed by Cohen and Glashow. The geometry of general very special relativity possesses a line element of Finsler geometry introduced by Bogoslovsky. We calculate the Einstein field equations and derive a modified Friedmann-Robertson-Walker cosmology for an osculating Riemannian space. The Friedmann equation of motion leads to an explanation of the cosmological acceleration in terms of an alternative non-Lorentz invariant theory. A first order approach for a primordial-spurionic vector field introduced into the metric gives back an estimation of the energy evolution and inflation.

Conceptual Development of Einstein's Mass-Energy Relationship

ERIC Educational Resources Information Center

Wong, Chee Leong; Yap, Kueh Chin

2005-01-01

Einstein's special theory of relativity was published in 1905. It stands as one of the greatest intellectual achievements in the history of human thought. Einstein described the equivalence of mass and energy as "the most important upshot of the special theory of relativity" (Einstein, 1919). In this paper, we will discuss the evolution of the…

Einstein's Jury: Trial by Telescope

NASA Astrophysics Data System (ADS)

Crelinsten, Jeffrey

2007-03-01

While Einstein's theory of relativity ultimately laid the foundation for modern studies of the universe, it took a long time to be accepted. Between 1905 and 1930, relativity was poorly understood and Einstein worked hard to try to make it more accessible to scientists and scientifically literate laypeople. Its acceptance was largely due to the astronomy community, which undertook precise measurements to test Einstein's astronomical predictions. The well-known 1919 British eclipse expeditions that made Einstein famous did not convince most scientists to accept relativity. The 1920s saw numerous attempts to measure light-bending, as well as solar line displacements and even ether-drift. How astronomers approached the ``Einstein problem'' in these early years before and after the First World War, and how the public reacted to what they reported, helped to shape attitudes we hold today about Einstein and his ideas.

Counterfactual Definiteness and Bell's Inequality

NASA Astrophysics Data System (ADS)

Hess, Karl; Raedt, Hans De; Michielsen, Kristel

Counterfactual definiteness must be used as at least one of the postulates or axioms that are necessary to derive Bell-type inequalities. It is considered by many to be a postulate that is not only commensurate with classical physics (as for example Einstein's special relativity), but also separates and distinguishes classical physics from quantum mechanics. It is the purpose of this paper to show that Bell's choice of mathematical functions and independent variables implicitly includes counterfactual definiteness and reduces the generality of the physics of Bell-type theories so significantly that no meaningful comparison of these theories with actual Einstein-Podolsky-Rosen experiments can be made.

Probing quantum gravity through exactly soluble midi-superspaces I

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ashtekar, A.; Pierri, M.

1996-12-01

It is well-known that the Einstein-Rosen solutions to the 3+1- dimensional vacuum Einstein{close_quote}s equations are in one to one correspondence with solutions of 2+1-dimensional general relativity coupled to axi-symmetric, zero rest mass scalar fields. We first re-examine the quantization of this midi-superspace paying special attention to the asymptotically flat boundary conditions and to certain functional analytic subtleties associated with regularization. We then use the resulting quantum theory to analyze several conceptual and technical issues of quantum gravity. {copyright} {ital 1996 American Institute of Physics.}

Relativity Based on Physical Processes Rather Than Space-Time

NASA Astrophysics Data System (ADS)

Giese, Albrecht

2013-09-01

Physicists' understanding of relativity and the way it is handled is at present dominated by the interpretation of Albert Einstein, who related relativity to specific properties of space and time. The principal alternative to Einstein's interpretation is based on a concept proposed by Hendrik A. Lorentz, which uses knowledge of classical physics to explain relativistic phenomena. In this paper, we will show that on the one hand the Lorentz-based interpretation provides a simpler mathematical way of arriving at the known results for both Special and General Relativity. On the other hand, it is able to solve problems which have remained open to this day. Furthermore, a particle model will be presented, based on Lorentzian relativity, which explains the origin of mass without the use of the Higgs mechanism, based on the finiteness of the speed of light, and which provides the classical results for particle properties that are currently only accessible through quantum mechanics.

Freundlich, Erwin Finlay (1885-1964)

NASA Astrophysics Data System (ADS)

Murdin, P.

2000-11-01

Born in Biebrich, Germany, collaborator with EINSTEIN, making measurements (successfully) of Mercury's orbit and the gravitational redshift (unsuccessfully) to confirm the general theory of relativity. Fled Nazi Germany to become the Napier Professor of Astronomy at the University of St Andrews in Scotland....

The Happiest thought of Einstein's Life

NASA Astrophysics Data System (ADS)

Heller, Michael

Finally, let us have a closer look at the place of the equivalence principle in the logical scheme of Einstein's general relativity theory. First, Einstein new well, from Minkowski's geometric formulation of his own special relativity, that accelerated motions should be represented as curved lines in a flat space-time. Second, the Galileo principle asserts that all bodies are accelerated in the same way in a given gravitational field, and consequently their motions are represented in the flat space-time by curved lines, all exactly in the same way. Third, since all lines representing free motions are curved exactly in the same way in the flat space-time, one can say that the lines remain straight (as far as possible) but the space-time itself becomes curved. Fourth, and last, since acceleration is (locally) equivalent to a gravitational field (here we have the equivalence principle), one is entitled to assert that it is the gravitational field (and not acceleration) that is represented as the curvature of space-time. This looks almost like an Aristotelian syllogism. However, to put all the pieces of evidence into the logical chain took Einstein a few years of hard thinking. The result has been incorporated into the field equations which quantitatively show how the curvature of space-time and gravity are linked together.

Entropy density of an adiabatic relativistic Bose-Einstein condensate star

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khaidir, Ahmad Firdaus; Kassim, Hasan Abu; Yusof, Norhasliza

Inspired by recent works, we investigate how the thermodynamics parameters (entropy, temperature, number density, energy density, etc) of Bose-Einstein Condensate star scale with the structure of the star. Below the critical temperature in which the condensation starts to occur, we study how the entropy behaves with varying temperature till it reaches its own stability against gravitational collapse and singularity. Compared to photon gases (pressure is described by radiation) where the chemical potential, μ is zero, entropy of photon gases obeys the Stefan-Boltzmann Law for a small values of T while forming a spiral structure for a large values of Tmore » due to general relativity. The entropy density of Bose-Einstein Condensate is obtained following the similar sequence but limited under critical temperature condition. We adopt the scalar field equation of state in Thomas-Fermi limit to study the characteristics of relativistic Bose-Einstein condensate under varying temperature and entropy. Finally, we obtain the entropy density proportional to (σT{sup 3}-3T) which obeys the Stefan-Boltzmann Law in ultra-relativistic condition.« less

Explicit formulae for Yang-Mills-Einstein amplitudes from the double copy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chiodaroli, Marco; Günaydin, Murat; Johansson, Henrik

Using the double-copy construction of Yang-Mills-Einstein theories formulated in our earlier work, we obtain compact presentations for single-trace Yang-Mills-Einstein tree amplitudes with up to five external gravitons and an arbitrary number of gluons. These are written as linear combinations of color-ordered Yang-Mills trees, where the coefficients are given by color/kinematics-satisfying numerators in a Yang-Mills + φ 3 theory. The construction outlined in this paper holds in general dimension and extends straightforwardly to supergravity theories. For one, two, and three external gravitons, our expressions give identical or simpler presentations of amplitudes already constructed through string-theory considerations or the scattering equations formalism.more » Our results are based on color/kinematics duality and gauge invariance, and strongly hint at a recursive structure underlying the single-trace amplitudes with an arbitrary number of gravitons. We also present explicit expressions for all-loop single-graviton Einstein-Yang-Mills amplitudes in terms of Yang-Mills amplitudes and, through gauge invariance, derive new all-loop amplitude relations for Yang-Mills theory.« less

Bounce universe from string-inspired Gauss-Bonnet gravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bamba, Kazuharu; Makarenko, Andrey N.; Myagky, Alexandr N.

2015-04-01

We explore cosmology with a bounce in Gauss-Bonnet gravity where the Gauss-Bonnet invariant couples to a dynamical scalar field. In particular, the potential and and Gauss-Bonnet coupling function of the scalar field are reconstructed so that the cosmological bounce can be realized in the case that the scale factor has hyperbolic and exponential forms. Furthermore, we examine the relation between the bounce in the string (Jordan) and Einstein frames by using the conformal transformation between these conformal frames. It is shown that in general, the property of the bounce point in the string frame changes after the frame is movedmore » to the Einstein frame. Moreover, it is found that at the point in the Einstein frame corresponding to the point of the cosmological bounce in the string frame, the second derivative of the scale factor has an extreme value. In addition, it is demonstrated that at the time of the cosmological bounce in the Einstein frame, there is the Gauss-Bonnet coupling function of the scalar field, although it does not exist in the string frame.« less

Focus: the elusive icon: Einstein, 1905-2005. Introduction.

PubMed

Galison, Peter

2004-12-01

As Einstein's portrait comes increasingly to resemble an icon, we lose more than detail--his writings and actions lose all reference. This is as true for his physics as it is for his philosophy and his politics; the best of recent work aims to remove Einstein's interventions from the abstract sphere of Delphic pronouncements and to insert them in the stream of real events, real arguments. Politically, this means attending to McCarthyism, Paul Robeson, the Arab-Israeli conflict. Philosophically, it means tying his concerns, for example, to late nineteenth-century neo-Kantian debates and to his own struggles inside science. And where physics is concerned, it means attending both in the narrow to his responses to others' work and his reactions to his own sometimes misfired early work on, for example, general relativity and to the wider context of technological developments. Einstein remains and will remain a magnet for historians, philosophers, and scientists; the essays assembled here represent a strong sampling--but only a sampling--of a fascinating new generation of work on this perennial figure.

Explicit formulae for Yang-Mills-Einstein amplitudes from the double copy

DOE PAGES

Chiodaroli, Marco; Günaydin, Murat; Johansson, Henrik; ...

2017-07-03

Using the double-copy construction of Yang-Mills-Einstein theories formulated in our earlier work, we obtain compact presentations for single-trace Yang-Mills-Einstein tree amplitudes with up to five external gravitons and an arbitrary number of gluons. These are written as linear combinations of color-ordered Yang-Mills trees, where the coefficients are given by color/kinematics-satisfying numerators in a Yang-Mills + φ 3 theory. The construction outlined in this paper holds in general dimension and extends straightforwardly to supergravity theories. For one, two, and three external gravitons, our expressions give identical or simpler presentations of amplitudes already constructed through string-theory considerations or the scattering equations formalism.more » Our results are based on color/kinematics duality and gauge invariance, and strongly hint at a recursive structure underlying the single-trace amplitudes with an arbitrary number of gravitons. We also present explicit expressions for all-loop single-graviton Einstein-Yang-Mills amplitudes in terms of Yang-Mills amplitudes and, through gauge invariance, derive new all-loop amplitude relations for Yang-Mills theory.« less

Focus: The elusive icon: Einstein, 1905-2005 - Introduction

NASA Astrophysics Data System (ADS)

Galison, Peter

2004-12-01

As Einstein's portrait comes increasingly to resemble an icon, we lose more than detail - his writings and actions lose all reference. This is as true for his physics as it is for his philosophy and his politics; the best of recent work aims to remove Einstein's interventions from the abstract sphere of Delphic pronouncements and to insert them in the stream of real events, real arguments. Politically, this means attending to McCarthyism, Paul Robeson, the Arab-Israeli conflict. Philosophically, it means tying his concerns, for example, to late nineteenth-century neo-Kantian debates and to his own struggles inside science. And where physics is concerned, it means attending both in the narrow to his reponses to others' work and his reactions to this own sometimes misfired early work on, for example, general relativity and to the wider context of technological developments. Einstein remains and will remain a magnet for historians, philosophers, and scientists; the essays assembled here represent a strong sampling - but only a sampling - of a fascinating new generation of work on this perennial figure.

Heterotic reduction of Courant algebroid connections and Einstein-Hilbert actions

NASA Astrophysics Data System (ADS)

Jurčo, Branislav; Vysoký, Jan

2016-08-01

We discuss Levi-Civita connections on Courant algebroids. We define an appropriate generalization of the curvature tensor and compute the corresponding scalar curvatures in the exact and heterotic case, leading to generalized (bosonic) Einstein-Hilbert type of actions known from supergravity. In particular, we carefully analyze the process of the reduction for the generalized metric, connection, curvature tensor and the scalar curvature.

Helmholtz, Riemann, and the Sirens: Sound, Color, and the "Problem of Space"

NASA Astrophysics Data System (ADS)

Pesic, Peter

2013-09-01

Emerging from music and the visual arts, questions about hearing and seeing deeply affected Hermann Helmholtz's and Bernhard Riemann's contributions to what became called the "problem of space [ Raumproblem]," which in turn influenced Albert Einstein's approach to general relativity. Helmholtz's physiological investigations measured the time dependence of nerve conduction and mapped the three-dimensional manifold of color sensation. His concurrent studies on hearing illuminated musical evidence through experiments with mechanical sirens that connect audible with visible phenomena, especially how the concept of frequency unifies motion, velocity, and pitch. Riemann's critique of Helmholtz's work on hearing led Helmholtz to respond and study Riemann's then-unpublished lecture on the foundations of geometry. During 1862-1870, Helmholtz applied his findings on the manifolds of hearing and seeing to the Raumproblem by supporting the quadratic distance relation Riemann had assumed as his fundamental hypothesis about geometrical space. Helmholtz also drew a "close analogy … in all essential relations between the musical scale and space." These intersecting studies of hearing and seeing thus led to reconsideration and generalization of the very concept of "space," which Einstein shaped into the general manifold of relativistic space-time.

Mass eigenstates in bimetric theory with matter coupling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmidt-May, Angnis, E-mail: angnis.schmidt-may@fysik.su.se

2015-01-01

In this paper we study the ghost-free bimetric action extended by a recently proposed coupling to matter through a composite metric. The equations of motion for this theory are derived using a method which avoids varying the square-root matrix that appears in the matter coupling. We make an ansatz for which the metrics are proportional to each other and find that it can solve the equations provided that one parameter in the action is fixed. In this case, the proportional metrics as well as the effective metric that couples to matter solve Einstein's equations of general relativity including a mattermore » source. Around these backgrounds we derive the quadratic action for perturbations and diagonalize it into generalized mass eigenstates. It turns out that matter only interacts with the massless spin-2 mode whose equation of motion has exactly the form of the linearized Einstein equations, while the field with Fierz-Pauli mass term is completely decoupled. Hence, bimetric theory, with one parameter fixed such that proportional solutions exist, is degenerate with general relativity up to linear order around these backgrounds.« less

The theory of spherically symmetric thin shells in conformal gravity

NASA Astrophysics Data System (ADS)

Berezin, Victor; Dokuchaev, Vyacheslav; Eroshenko, Yury

The spherically symmetric thin shells are the nearest generalizations of the point-like particles. Moreover, they serve as the simple sources of the gravitational fields both in General Relativity and much more complex quadratic gravity theories. We are interested in the special and physically important case when all the quadratic in curvature tensor (Riemann tensor) and its contractions (Ricci tensor and scalar curvature) terms are present in the form of the square of Weyl tensor. By definition, the energy-momentum tensor of the thin shell is proportional to Diracs delta-function. We constructed the theory of the spherically symmetric thin shells for three types of gravitational theories with the shell: (1) General Relativity; (2) Pure conformal (Weyl) gravity where the gravitational part of the total Lagrangian is just the square of the Weyl tensor; (3) Weyl-Einstein gravity. The results are compared with these in General Relativity (Israel equations). We considered in detail the shells immersed in the vacuum. Some peculiar properties of such shells are found. In particular, for the traceless ( = massless) shell, it is shown that their dynamics cannot be derived from the matching conditions and, thus, is completely arbitrary. On the contrary, in the case of the Weyl-Einstein gravity, the trajectory of the same type of shell is completely restored even without knowledge of the outside solution.

Astronomers' Race to Test Relativity, 1911-1930

NASA Astrophysics Data System (ADS)

Crelinsten, Jeffrey

2006-11-01

Einstein's theory of relativity changed our notions of space and time and has dramatically altered the way we look at the universe and our place in it. Yet to this day a working knowledge of the theory is beyond most people. In today's popular culture, Einstein is a remote, loveable genius and his theory is incomprehensible. While Einstein's theory ultimately laid the foundation for modern studies of the universe, it took a long time to be accepted. Between 1905 and 1930, relativity was poorly understood and Einstein worked hard to try to make it more accessible to scientists and scientifically literate laypeople. Its acceptance was largely due to the astronomy community, which undertook precise measurements to test Einstein's astronomical predictions. How astronomers approached the ``Einstein problem'' in these early years and how the public reacted to what they reported helped to shape attitudes we hold today about Einstein and his ideas.

On the asserted clash between the Freud and the Bianchi identities

NASA Astrophysics Data System (ADS)

Antoci, S.

1995-09-01

Through a constructive method it is shown that the claim advanced in recent times about a clash that should occur between the Freud and the Bianchi identities in Einstein's general theory of relativity is based on a faulty argument.

A New Model of Special Relativity and the Relationship between the Time Warps of General and Special Relativity

ERIC Educational Resources Information Center

Stannard, Warren B.

2018-01-01

Einstein's two theories of relativity were introduced over 100 years ago. High school science students are seldom exposed to these revolutionary ideas as they are often perceived to be too difficult conceptually and mathematically. This paper brings together the two theories of relativity in a way that is logical and consistent and enables the…

Cosmic transit and anisotropic models in f(R,T) gravity

NASA Astrophysics Data System (ADS)

Sahu, S. K.; Tripathy, S. K.; Sahoo, P. K.; Nath, A.

2017-06-01

Accelerating cosmological models are constructed in a modified gravity theory dubbed as $f(R,T)$ gravity at the backdrop of an anisotropic Bianchi type-III universe. $f(R,T)$ is a function of the Ricci scalar $R$ and the trace $T$ of the energy-momentum tensor and it replaces the Ricci scalar in the Einstein-Hilbert action of General Relativity. The models are constructed for two different ways of modification of the Einstein-Hilbert action. Exact solutions of the field equations are obtained by a novel method of integration. We have explored the behaviour of the cosmic transit from an decelerated phase of expansion to an accelerated phase to get the dynamical features of the universe. Within the formalism of the present work, it is found that, the modification of the Einstein-Hilbert action does not affect the scale factor. However the dynamics of the effective dark energy equation of state is significantly affected.

Gravitational catalysis of merons in Einstein-Yang-Mills theory

NASA Astrophysics Data System (ADS)

Canfora, Fabrizio; Oh, Seung Hun; Salgado-Rebolledo, Patricio

2017-10-01

We construct regular configurations of the Einstein-Yang-Mills theory in various dimensions. The gauge field is of meron-type: it is proportional to a pure gauge (with a suitable parameter λ determined by the field equations). The corresponding smooth gauge transformation cannot be deformed continuously to the identity. In the three-dimensional case we consider the inclusion of a Chern-Simons term into the analysis, allowing λ to be different from its usual value of 1 /2 . In four dimensions, the gravitating meron is a smooth Euclidean wormhole interpolating between different vacua of the theory. In five and higher dimensions smooth meron-like configurations can also be constructed by considering warped products of the three-sphere and lower-dimensional Einstein manifolds. In all cases merons (which on flat spaces would be singular) become regular due to the coupling with general relativity. This effect is named "gravitational catalysis of merons".

The Glimm scheme for perfect fluids on plane-symmetric Gowdy spacetimes

NASA Astrophysics Data System (ADS)

Barnes, A. P.; Lefloch, P. G.; Schmidt, B. G.; Stewart, J. M.

2004-11-01

We propose a new, augmented formulation of the coupled Euler Einstein equations for perfect fluids on plane-symmetric Gowdy spacetimes. The unknowns of the augmented system are the density and velocity of the fluid and the first- and second-order spacetime derivatives of the metric. We solve the Riemann problem for the augmented system, allowing propagating discontinuities in both the fluid variables and the first- and second-order derivatives of the geometry coefficients. Our main result, based on Glimm's random choice scheme, is the existence of solutions with bounded total variation of the Euler Einstein equations, up to the first time where a blow-up singularity (unbounded first-order derivatives of the geometry coefficients) occurs. We demonstrate the relevance of the augmented system for numerical relativity. We also consider general vacuum spacetimes and solve a Riemann problem, by relying on a theorem by Rendall on the characteristic value problem for the Einstein equations.

Lectures on gravitation

NASA Astrophysics Data System (ADS)

Das, Ashok

1. Basics of geometry and relativity. 1.1. Two dimensional geometry. 1.2. Inertial and gravitational masses. 1.3. Relativity -- 2. Relativistic dynamics. 2.1. Relativistic point particle. 2.2. Current and charge densities. 2.3. Maxwell's equations in the presence of sources. 2.4. Motion of a charged particle in EM field. 2.5. Energy-momentum tensor. 2.6. Angular momentum -- 3. Principle of general covariance. 3.1. Principle of equivalence. 3.2. Principle of general covariance. 3.3. Tensor densities -- 4. Affine connection and covariant derivative. 4.1. Parallel transport of a vector. 4.2. Christoffel symbol. 4.3. Covariant derivative of contravariant tensors. 4.4. Metric compatibility. 4.5. Covariant derivative of covariant and mixed tensors. 4.6. Electromagnetic analogy. 4.7. Gradient, divergence and curl -- 5. Geodesic equation. 5.1. Covariant differentiation along a curve. 5.2. Curvature from derivatives. 5.3. Parallel transport along a closed curve. 5.4. Geodesic equation. 5.5. Derivation of geodesic equation from a Lagrangian -- 6. Applications of the geodesic equation. 6.1. Geodesic as representing gravitational effect. 6.2. Rotating coordinate system and the Coriolis force. 6.3. Gravitational red shift. 6.4. Twin paradox and general covariance. 6.5. Other equations in the presence of gravitation -- 7. Curvature tensor and Einstein's equation. 7.1. Curvilinear coordinates versus gravitational field. 7.2. Definition of an inertial coordinate frame. 7.3. Geodesic deviation. 7.4. Properties of the curvature tensor. 7.5. Einstein's equation. 7.6. Cosmological constant. 7.7. Initial value problem. 7.8. Einstein's equation from an action -- 8. Schwarzschild solution. 8.1. Line element. 8.2. Connection. 8.3. Solution of the Einstein equation. 8.4. Properties of the Schwarzschild solution. 8.5. Isotropic coordinates -- 9. Tests of general relativity. 9.1. Radar echo experiment. 9.2. Motion of a particle in a Schwarzschild background. 9.3. Motion of light rays in a Schwarzschild background. 9.4. Perihelion advance of Mercury -- 10. Black holes. 10.1. Singularities of the metric. 10.2. Singularities of the Schwarzschild metric. 10.3. Black holes -- 11. Cosmological models and the big bang theory. 11.1. Homogeneity and isotropy. 11.2. Different models of the universe. 11.3. Hubble's law. 11.4. Evolution equation. 11.5. Big bang theory and blackbody radiation.

Weber's gravitational force as static weak field approximation

NASA Astrophysics Data System (ADS)

Tiandho, Yuant

2016-02-01

Weber's gravitational force (WGF) is one of gravitational model that can accommodate a non-static system because it depends not only on the distance but also on the velocity and the acceleration. Unlike Newton's law of gravitation, WGF can predict the anomalous of Mercury and gravitational bending of light near massive object very well. Then, some researchers use WGF as an alternative model of gravitation and propose a new mechanics theory namely the relational mechanics theory. However, currently we have known that the theory of general relativity which proposed by Einstein can explain gravity with very accurate. Through the static weak field approximation for the non-relativistic object, we also have known that the theory of general relativity will reduce to Newton's law of gravity. In this work, we expand the static weak field approximation that compatible with relativistic object and we obtain a force equation which correspond to WGF. Therefore, WGF is more precise than Newton's gravitational law. The static-weak gravitational field that we used is a solution of the Einstein's equation in the vacuum that satisfy the linear field approximation. The expression of WGF with ξ = 1 and satisfy the requirement of energy conservation are obtained after resolving the geodesic equation. By this result, we can conclude that WGF can be derived from the general relativity.

Space-time philosophy reconstructed via massive Nordström scalar gravities? Laws vs. geometry, conventionality, and underdetermination

NASA Astrophysics Data System (ADS)

Pitts, J. Brian

2016-02-01

What if gravity satisfied the Klein-Gordon equation? Both particle physics from the 1920-30s and the 1890s Neumann-Seeliger modification of Newtonian gravity with exponential decay suggest considering a "graviton mass term" for gravity, which is algebraic in the potential. Unlike Nordström's "massless" theory, massive scalar gravity is strictly special relativistic in the sense of being invariant under the Poincaré group but not the 15-parameter Bateman-Cunningham conformal group. It therefore exhibits the whole of Minkowski space-time structure, albeit only indirectly concerning volumes. Massive scalar gravity is plausible in terms of relativistic field theory, while violating most interesting versions of Einstein's principles of general covariance, general relativity, equivalence, and Mach. Geometry is a poor guide to understanding massive scalar gravity(s): matter sees a conformally flat metric due to universal coupling, but gravity also sees the rest of the flat metric (barely or on long distances) in the mass term. What is the 'true' geometry, one might wonder, in line with Poincaré's modal conventionality argument? Infinitely many theories exhibit this bimetric 'geometry,' all with the total stress-energy's trace as source; thus geometry does not explain the field equations. The irrelevance of the Ehlers-Pirani-Schild construction to a critique of conventionalism becomes evident when multi-geometry theories are contemplated. Much as Seeliger envisaged, the smooth massless limit indicates underdetermination of theories by data between massless and massive scalar gravities-indeed an unconceived alternative. At least one version easily could have been developed before General Relativity; it then would have motivated thinking of Einstein's equations along the lines of Einstein's newly re-appreciated "physical strategy" and particle physics and would have suggested a rivalry from massive spin 2 variants of General Relativity (massless spin 2, Pauli and Fierz found in 1939). The Putnam-Grünbaum debate on conventionality is revisited with an emphasis on the broad modal scope of conventionalist views. Massive scalar gravity thus contributes to a historically plausible rational reconstruction of much of 20th-21st century space-time philosophy in the light of particle physics. An appendix reconsiders the Malament-Weatherall-Manchak conformal restriction of conventionality and constructs the 'universal force' influencing the causal structure. Subsequent works will discuss how massive gravity could have provided a template for a more Kant-friendly space-time theory that would have blocked Moritz Schlick's supposed refutation of synthetic a priori knowledge, and how Einstein's false analogy between the Neumann-Seeliger-Einstein modification of Newtonian gravity and the cosmological constant Λ generated lasting confusion that obscured massive gravity as a conceptual possibility.

Rediscovering Einstein's legacy: How Einstein anticipates Kuhn and Feyerabend on the nature of science.

PubMed

Oberheim, Eric

2016-06-01

Thomas Kuhn and Paul Feyerabend promote incommensurability as a central component of their conflicting accounts of the nature of science. This paper argues that in so doing, they both develop Albert Einstein's views, albeit in different directions. Einstein describes scientific revolutions as conceptual replacements, not mere revisions, endorsing 'Kant-on-wheels' metaphysics in light of 'world change'. Einstein emphasizes underdetermination of theory by evidence, rational disagreement in theory choice, and the non-neutrality of empirical evidence. Einstein even uses the term 'incommensurable' specifically to apply to challenges posed to comparatively evaluating scientific theories in 1949, more than a decade before Kuhn and Feyerabend. This analysis shows how Einstein anticipates substantial components of Kuhn and Feyerabend's views, and suggests that there are strong reasons to suspect that Kuhn and Feyerabend were directly inspired by Einstein's use of the term 'incommensurable', as well as his more general methodological and philosophical reflections. Copyright © 2015 Elsevier Ltd. All rights reserved.

KSC-04pd0940

NASA Image and Video Library

2004-04-20

KENNEDY SPACE CENTER, FLA. - The Gravity Probe B spacecraft, atop a Boeing Delta II vehicle, launches at 12:57:24 p.m. EDT from Space Launch Complex 2 at Vandenberg Air Force Base, Calif. Gravity Probe B is the relativity gyroscope experiment being developed by NASA and Stanford University to test two extraordinary, unverified predictions of Albert Einstein's general theory of relativity.

KSC-04PD-0940

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. The Gravity Probe B spacecraft, atop a Boeing Delta II vehicle, launches at 12:57:24 p.m. EDT from Space Launch Complex 2 at Vandenberg Air Force Base, Calif. Gravity Probe B is the relativity gyroscope experiment being developed by NASA and Stanford University to test two extraordinary, unverified predictions of Albert Einstein's general theory of relativity.

Lunar surface gravimeter experiment

NASA Technical Reports Server (NTRS)

Giganti, J. J.; Larson, J. V.; Richard, J. P.; Tobias, R. L.; Weber, J.

1977-01-01

The lunar surface gravimeter used the moon as an instrumented antenna to search for gravitational waves predicted by Einstein's general theory of relativity. Tidal deformation of the moon was measured. Gravitational radiation is a channel that is capable of giving information about the structure and evolution of the universe.

Black Holes: A Selected Bibliography.

ERIC Educational Resources Information Center

Fraknoi, Andrew

1991-01-01

Offers a selected bibliography pertaining to black holes with the following categories: introductory books; introductory articles; somewhat more advanced articles; readings about Einstein's general theory of relativity; books on the death of stars; articles on the death of stars; specific articles about Supernova 1987A; relevant science fiction…

Gravitational-Wave Tests of General Relativity with Ground-Based Detectors and Pulsar-Timing Arrays.

PubMed

Yunes, Nicolás; Siemens, Xavier

2013-01-01

This review is focused on tests of Einstein's theory of general relativity with gravitational waves that are detectable by ground-based interferometers and pulsar-timing experiments. Einstein's theory has been greatly constrained in the quasi-linear, quasi-stationary regime, where gravity is weak and velocities are small. Gravitational waves will allow us to probe a complimentary, yet previously unexplored regime: the non-linear and dynamical strong-field regime . Such a regime is, for example, applicable to compact binaries coalescing, where characteristic velocities can reach fifty percent the speed of light and gravitational fields are large and dynamical. This review begins with the theoretical basis and the predicted gravitational-wave observables of modified gravity theories. The review continues with a brief description of the detectors, including both gravitational-wave interferometers and pulsar-timing arrays, leading to a discussion of the data analysis formalism that is applicable for such tests. The review ends with a discussion of gravitational-wave tests for compact binary systems.

Book Review: The future of spacetime. Stephen William Hawking (ed.); Kip S. Thorne, Igor Novikov, Timothy Ferris, Alan Lightman, and Richard Price, W.W. Norton & Company, 2002, 224 pp., US 25.95, ISBN 0393020223

NASA Astrophysics Data System (ADS)

Smeenk, Chris

2003-12-01

The study of Einstein's theory of general relativity experienced a renaissance beginning in the early 1960s. Prior to this resurgence of interest, general relativity was isolated from mainstream physics-admired for its elegance, perhaps, but only from a distance. The generation of students who risked their careers by entering this neglected field has now reached the age of festschrifts. In June of 2000, Caltech hosted ;Kipfest,; a conference in honor of Kip Thorne's 60th birthday. Thorne started graduate school at Princeton in 1962 and began research in general relativity under John Wheeler's guidance in the heady early days of the renaissance. Since then, he has played a prominent role in general relativity: as co-author of the influential textbook Gravitation, as a leader in research regarding astrophysical applications of Einstein's theory, and as a co-founder and chief advocate for the Laser Interferometer Gravitational Wave Observatory (LIGO), to mention a few aspects of his far-reaching work. ;Kipfest; included 14 speakers discussing fields to which Thorne has contributed. But the conference also reflected Thorne's long-standing commitment to communicating science to a general audience: Igor Novikov, Stephen Hawking, Timothy Ferris, and Alan Lightman gave popular talks at ;Kipfest,; with Thorne himself tricked into delivering a fifth. The Future of Spacetime gathers adaptations of these five lectures, along with a lengthy introductory essay by Richard Price.

Hamiltonian approach to GR - Part 1: covariant theory of classical gravity

NASA Astrophysics Data System (ADS)

Cremaschini, Claudio; Tessarotto, Massimo

2017-05-01

A challenging issue in General Relativity concerns the determination of the manifestly covariant continuum Hamiltonian structure underlying the Einstein field equations and the related formulation of the corresponding covariant Hamilton-Jacobi theory. The task is achieved by adopting a synchronous variational principle requiring distinction between the prescribed deterministic metric tensor \\widehat{g}(r)≡ { \\widehat{g}_{μ ν }(r)} solution of the Einstein field equations which determines the geometry of the background space-time and suitable variational fields x≡ { g,π } obeying an appropriate set of continuum Hamilton equations, referred to here as GR-Hamilton equations. It is shown that a prerequisite for reaching such a goal is that of casting the same equations in evolutionary form by means of a Lagrangian parametrization for a suitably reduced canonical state. As a result, the corresponding Hamilton-Jacobi theory is established in manifestly covariant form. Physical implications of the theory are discussed. These include the investigation of the structural stability of the GR-Hamilton equations with respect to vacuum solutions of the Einstein equations, assuming that wave-like perturbations are governed by the canonical evolution equations.

Cosmic time and reduced phase space of general relativity

NASA Astrophysics Data System (ADS)

Ita, Eyo Eyo; Soo, Chopin; Yu, Hoi-Lai

2018-05-01

In an ever-expanding spatially closed universe, the fractional change of the volume is the preeminent intrinsic time interval to describe evolution in general relativity. The expansion of the universe serves as a subsidiary condition which transforms Einstein's theory from a first class to a second class constrained system when the physical degrees of freedom (d.o.f.) are identified with transverse traceless excitations. The super-Hamiltonian constraint is solved by eliminating the trace of the momentum in terms of the other variables, and spatial diffeomorphism symmetry is tackled explicitly by imposing transversality. The theorems of Maskawa-Nishijima appositely relate the reduced phase space to the physical variables in canonical functional integral and Dirac's criterion for second class constraints to nonvanishing Faddeev-Popov determinants in the phase space measures. A reduced physical Hamiltonian for intrinsic time evolution of the two physical d.o.f. emerges. Freed from the first class Dirac algebra, deformation of the Hamiltonian constraint is permitted, and natural extension of the Hamiltonian while maintaining spatial diffeomorphism invariance leads to a theory with Cotton-York term as the ultraviolet completion of Einstein's theory.

BOOK REVIEW: Einsteins Kosmos. Untersuchungen zur Geschichte der Kosmologie Relativitatstheorie und zu Einsteins Wirken und Nachwirken

NASA Astrophysics Data System (ADS)

Sterken, C.; Duerbeck, H. W.; Dick, W. R.

2006-12-01

This book collects about 15 papers (most of them by one single author) on Einstein and the history of general relativity (GR) and the foundations of relativistic cosmology. The matter not only deals with Einstein and his times, but also with pre-GR ideas, and with the interplay of Einstein and his colleagues (opposing as well as supporting personalities). As the title indicates, all papers are written in German, but they include comprehensive Abstracts both in German and English. The book is illustrated with quite a number classical - but also some far more original though not less beautiful - photographs and facsimiles of documents. The book is edited very well, though the style of references is not quite homogeneous. There is no Index. K. Hentschel covers Einstein's argumentation for the existence of graviational redshift, and the initial search for empirical support. The error analysis of observational evidence supporting relativistic light deflection is discussed in a paper by P. Brosche. In particular, H. Duerbeck and P. Flin - in their description of the life and work of Silberstein, who was quite sceptic on the significance of the observational verifications a la Eddington - include the transcription of two most revealing letters by Silberstein to Sommerfeld (1919) and to Einstein (1934). In the first letter, Silberstein clearly shows his scientific maturity and integrity by scrutinising the observational evidence supporting light deflection, presented at a joint meeting of the Royal Society and the Royal Astronomical Society. The second letter, which is more a personal letter, includes lots of political references and connotations. Some of Einstein's political views are also revealed by D.B. Herrmann on the basis of his own correspondence with E.G. Straus, a collaborator of Einstein's. In a consequent paper, S. Grundmann gives remarks on Herrmann's contribution and illustrates Einstein's attitude towards Marx, Engels, Lenin and Stalin. M. Schemmel discusses Schwarzschild's cosmological speculations, and wonders why some people do immediately grasp the meaning and consequence of newly proposed doctrines, whereas the bulk of the contemporaneous scientists respond in a rather low profile. T. Jung reviews Einstein's contribution to cosmology, leading to the Friedmann-Einstein and Einstein-de Sitter universes (with a detailed Appendix on the Friedmann-Lemaitre cosmology), and also presents the cosmological work of Selety, and his correspondence with Einstein. In a subsequent paper, H.-J. Schmidt comments on Einstein's criticism on de Sitter's solution of the Einstein field equations. Controversies with Einstein are elaborated by G. Singer (on Friedmann) and by K. Roessler (on Lemaitre). J. Renn and T. Sauer discuss Mandl's role in the publication history of Einstein's papers, notably Einstein's short paper on gravitational lensing. Finally, the book concludes with a contribution by D.B. Herrmann about the relationship between Einstein and Archenhold Observatory (where Einstein gave his first Berlin popular lecture in 1915), the transcription of H.-J. Treder's 1979 public address at the Einstein memorial plaque, and an inventory list of about 50 Einstein memorabilia - monuments, busts, plaques - compiled by W.R. Dick. This book is based on ideas approached in a historical context from the individual perspective of the authors. It is a real treasure trove of information and basic references on the history of GR, and it also covers quite some grounds with mathematical equations.

Einstein: A Historical Perspective

NASA Astrophysics Data System (ADS)

Kormos-Buchwald, Diana

2015-04-01

In late 1915, Albert Einstein (1879-1955) completed as series of papers on a generalized theory of gravitation that were to constitute a major conceptual change in the history of modern physics and the crowning achievement of his scientific career. But this accomplishment came after a decade of intense intellectual struggle and was received with muted enthusiasm. Einstein's previously unpublished writings and massive correspondence, edited by the Einstein Papers Project, provide vivid insights into the historical, personal, and scientific context of the formulation, completion, and reception of GR during the first decades of the 20th century.

Spin coefficients and gauge fixing in the Newman-Penrose formalism

NASA Astrophysics Data System (ADS)

Nerozzi, Andrea

2017-03-01

Since its introduction in 1962, the Newman-Penrose formalism has been widely used in analytical and numerical studies of Einstein's equations, like for example for the Teukolsky master equation, or as a powerful wave extraction tool in numerical relativity. Despite the many applications, Einstein's equations in the Newman-Penrose formalism appear complicated and not easily applicable to general studies of spacetimes, mainly because physical and gauge degrees of freedom are mixed in a nontrivial way. In this paper we approach the whole formalism with the goal of expressing the spin coefficients as functions of tetrad invariants once a particular tetrad is chosen. We show that it is possible to do so, and give for the first time a general recipe for the task, as well as an indication of the quantities and identities that are required.

Space-time slicing in Horndeski theories and its implications for non-singular bouncing solutions

NASA Astrophysics Data System (ADS)

Ijjas, Anna

2018-02-01

In this paper, we show how the proper choice of gauge is critical in analyzing the stability of non-singular cosmological bounce solutions based on Horndeski theories. We show that it is possible to construct non-singular cosmological bounce solutions with classically stable behavior for all modes with wavelengths above the Planck scale where: (a) the solution involves a stage of null-energy condition violation during which gravity is described by a modification of Einstein's general relativity; and (b) the solution reduces to Einstein gravity both before and after the null-energy condition violating stage. Similar considerations apply to galilean genesis scenarios.

Einstein’s Legacy to Astronomy: From Black Holes to the Expanding Universe

NASA Astrophysics Data System (ADS)

Bartusiak, Marcia

2006-12-01

Albert Einstein placed a formidable imprint on astronomy. Not since the time of Isaac Newton, three centuries ago, has a single individual so influenced the field. Many of the great astronomical findings of the 20th century--the expanding universe, compact stars, origin of the Sun’s power, black holes, gravitational lensing, dark energy, gravity waves--are rooted in the physics that Einstein so brilliantly deduced. This illustrated presentation, the Gemant Award Lecture sponsored by the American Institute of Physics, will provide a guided tour through the cosmos and explain how our understanding of the universe was transformed by Einstein’s theories of special and general relativity.

Generalized wave operators, weighted Killing fields, and perturbations of higher dimensional spacetimes

NASA Astrophysics Data System (ADS)

Araneda, Bernardo

2018-04-01

We present weighted covariant derivatives and wave operators for perturbations of certain algebraically special Einstein spacetimes in arbitrary dimensions, under which the Teukolsky and related equations become weighted wave equations. We show that the higher dimensional generalization of the principal null directions are weighted conformal Killing vectors with respect to the modified covariant derivative. We also introduce a modified Laplace–de Rham-like operator acting on tensor-valued differential forms, and show that the wave-like equations are, at the linear level, appropriate projections off shell of this operator acting on the curvature tensor; the projection tensors being made out of weighted conformal Killing–Yano tensors. We give off shell operator identities that map the Einstein and Maxwell equations into weighted scalar equations, and using adjoint operators we construct solutions of the original field equations in a compact form from solutions of the wave-like equations. We study the extreme and zero boost weight cases; extreme boost corresponding to perturbations of Kundt spacetimes (which includes near horizon geometries of extreme black holes), and zero boost to static black holes in arbitrary dimensions. In 4D our results apply to Einstein spacetimes of Petrov type D and make use of weighted Killing spinors.

The simplicial Ricci tensor

NASA Astrophysics Data System (ADS)

Alsing, Paul M.; McDonald, Jonathan R.; Miller, Warner A.

2011-08-01

The Ricci tensor (Ric) is fundamental to Einstein's geometric theory of gravitation. The three-dimensional Ric of a spacelike surface vanishes at the moment of time symmetry for vacuum spacetimes. The four-dimensional Ric is the Einstein tensor for such spacetimes. More recently, the Ric was used by Hamilton to define a nonlinear, diffusive Ricci flow (RF) that was fundamental to Perelman's proof of the Poincarè conjecture. Analytic applications of RF can be found in many fields including general relativity and mathematics. Numerically it has been applied broadly to communication networks, medical physics, computer design and more. In this paper, we use Regge calculus (RC) to provide the first geometric discretization of the Ric. This result is fundamental for higher dimensional generalizations of discrete RF. We construct this tensor on both the simplicial lattice and its dual and prove their equivalence. We show that the Ric is an edge-based weighted average of deficit divided by an edge-based weighted average of dual area—an expression similar to the vertex-based weighted average of the scalar curvature reported recently. We use this Ric in a third and independent geometric derivation of the RC Einstein tensor in arbitrary dimensions.

General relativity in two dimensions: A Hamilton-Jacobi analysis

NASA Astrophysics Data System (ADS)

Bertin, M. C.; Pimentel, B. M.; Pompeia, P. J.

2010-11-01

We analyzed the constraint structure of the Einstein-Hilbert first-order action in two dimensions using the Hamilton-Jacobi approach. We were able to find a set of involutive, as well as a set of non-involutive constraints. Using generalized brackets we showed how to assure integrability of the theory, to eliminate the set of non-involutive constraints and how to build the field equations.

On static black holes solutions in Einstein and Einstein-Gauss-Bonnet gravity with topology [Formula: see text].

PubMed

Dadhich, Naresh; Pons, Josep M

We study static black hole solutions in Einstein and Einstein-Gauss-Bonnet gravity with the topology of the product of two spheres, [Formula: see text], in higher dimensions. There is an unusual new feature of the Gauss-Bonnet black hole: the avoidance of a non-central naked singularity prescribes a mass range for the black hole in terms of [Formula: see text]. For an Einstein-Gauss-Bonnet black hole a limited window of negative values for [Formula: see text] is also permitted. This topology encompasses black strings, branes, and generalized Nariai metrics. We also give new solutions with the product of two spheres of constant curvature.

The prototype design of the Stanford Relativity Gyro Experiment

NASA Technical Reports Server (NTRS)

Parkinson, Bradford W.; Everitt, C. W. Francis; Turneaure, John P.; Parmley, Richard T.

1987-01-01

The Stanford Relativity Gyroscope Experiment constitutes a fundamental test of Einstein's General Theory of Relativity, probing such heretofore untested aspects of the theory as those that relate to spin by means of drag-free satellite-borne gyroscopes. General Relativity's prediction of two orthogonal precessions (motional and geodetic) for a perfect Newtonian gyroscope in polar orbit has not yet been experimentally assessed, and will mark a significant advancement in experimental gravitation. The technology employed in the experiment has been under development for 25 years at NASA's Marshall Space Flight Center. Four fused quartz gyroscopes will be used.

Those Elusive Gravitational Waves

ERIC Educational Resources Information Center

MOSAIC, 1976

1976-01-01

The presence of gravitational waves was predicted by Einstein in his theory of General Relativity. Since then, scientists have been attempting to develop a detector sensitive enough to measure these cosmic signals. Once the presence of gravitational waves is confirmed, scientists can directly study star interiors, galaxy cores, or quasars. (MA)

New method for the detection of light deflection by solar gravity.

PubMed

Shapiro, I I

1967-08-18

The prediction of Einstein's theory of general relativity that light will be deflected by the sun may be tested by sending radio waves from the earth to Venus or Mercury when either passes behind the sun and detecting the echoes with a radar interferometer.

Arguments concerning Relativity and Cosmology.

PubMed

Klein, O

1971-01-29

In the first place I have reviewed the true foundation of Einstein's theory of general relativity, the so-called principle of equivalence, according to which there is no essential difference between "genuine" gravitation and inertial forces, well known from accelerated vehicles. By means of a comparison with Gaussian geometry of curved surfaces-the background of Riemannian geometry, the tool used by Einstein for the mathematical formulation of his theory-it is made clear that this principle is incompatible with the idea proposed by Mach and accepted by Einstein as an incitement to his attempt to describe the main situation in the universe as an analogy in three dimensions to the closed surface of a sphere. In the later attempts toward a mathematical description of the universe, where Einstein's cosmology was adapted to the discovery by Hubble that its observed part is expanding, the socalled cosmological postulate has been used as a kind of axiomatic background which, when analyzed, makes it probable that this expansion is shared by a very big, but still bounded system. This implies that our expanding metagalaxy is probably just one of a type of stellar objects in different phases of evolution, some expanding and some contracting. Some attempts toward the description of this evolution are sketched in the article with the hope that further investigation, theoretical and observational, may lead to an interesting advance in this part of astrophysics.

The Friedmann-Lemaître-Robertson-Walker Big Bang Singularities are Well Behaved

NASA Astrophysics Data System (ADS)

Stoica, Ovidiu Cristinel

2016-01-01

We show that the Big Bang singularity of the Friedmann-Lemaître-Robertson-Walker model does not raise major problems to General Relativity. We prove a theorem showing that the Einstein equation can be written in a non-singular form, which allows the extension of the spacetime before the Big Bang. The physical interpretation of the fields used is discussed. These results follow from our research on singular semi-Riemannian geometry and singular General Relativity.

Testing general relativity in space-borne and astronomical laboratories

NASA Technical Reports Server (NTRS)

Will, Clifford M.

1989-01-01

The current status of space-based experiments and astronomical observations designed to test the theory of general relativity is surveyed. Consideration is given to tests of post-Newtonian gravity, searches for feeble short-range forces and gravitomagnetism, improved measurements of parameterized post-Newtonian parameter values, explorations of post-Newtonian physics, tests of the Einstein equivalence principle, observational tests of post-Newtonian orbital effects, and efforts to detect quadrupole and dipole radiation damping. Recent numerical results are presented in tables.

Teaching Einsteinian physics at schools: part 1, models and analogies for relativity

NASA Astrophysics Data System (ADS)

Kaur, Tejinder; Blair, David; Moschilla, John; Stannard, Warren; Zadnik, Marjan

2017-11-01

The Einstein-First project aims to change the paradigm of school science teaching through the introduction of modern Einsteinian concepts of space and time, gravity and quanta at an early age. These concepts are rarely taught to school students despite their central importance to modern science and technology. The key to implementing the Einstein-First curriculum is the development of appropriate models and analogies. This paper is the first part of a three-paper series. It presents the conceptual foundation of our approach, based on simple physical models and analogies, followed by a detailed description of the models and analogies used to teach concepts of general and special relativity. Two accompanying papers address the teaching of quantum physics (Part 2) and research outcomes (Part 3).

The Einstein Dossiers: Science and Politics - Einstein's Berlin Period with an Appendix on Einstein's FBI File

NASA Astrophysics Data System (ADS)

Grundmann, Siegfried

In 1919 the Prussian Ministry of Science, Arts and Culture opened a dossier on "Einstein's Theory of Relativity." It was rediscovered by the author in 1961 and is used in conjunction with numerous other subsequently identified 'Einstein' files as the basis of this fascinating book. In particular, the author carefully scrutinizes Einstein's FBI file from 1950-55 against mostly unpublished material from European including Soviet sources and presents hitherto unknown documentation on Einstein's alleged contacts with the German Communist Party and the Comintern.

Mistaken Identity and Mirror Images: Albert and Carl Einstein, Leiden and Berlin, Relativity and Revolution

NASA Astrophysics Data System (ADS)

van Dongen, Jeroen

2012-06-01

Albert Einstein accepted a "special" visiting professorship at the University of Leiden in the Netherlands in February 1920. Although his appointment should have been a mere formality, it took until October of that year before Einstein could occupy his special chair. Why the delay? The explanation involves a case of mistaken identity with Carl Einstein, Dadaist art, and a particular Dutch fear of revolutions. But what revolutions was one afraid of? The story of Einstein's Leiden chair throws new light on the reception of relativity and its creator in the Netherlands and in Germany.

A Particle Model Explaining Mass and Relativity in a Physical Way

NASA Astrophysics Data System (ADS)

Giese, Albrecht

Physicists' understanding of relativity and the way it is handled is up to present days dominated by the interpretation of Albert Einstein, who related relativity to specific properties of space and time. The principal alternative to Einstein's interpretation is based on a concept proposed by Hendrik A. Lorentz, which uses knowledge of classical physics alone to explain relativistic phenomena. In this paper, we will show that on the one hand the Lorentz-based interpretation provides a simpler mathematical way of arriving at the known results for both Special and General Relativity. On the other hand, it is able to solve problems which have remained open to this day. Furthermore, a particle model will be presented, based on Lorentzian relativity and the quantum mechanical concept of Louis de Broglie, which explains the origin of mass without the use of the Higgs mechanism. It is based on the finiteness of the speed of light and provides classical results for particle properties which are currently only accessible through quantum mechanics.

Boundary stress tensor and asymptotically AdS3 non-Einstein spaces at the chiral point

NASA Astrophysics Data System (ADS)

Giribet, Gaston; Goya, Andrés; Leston, Mauricio

2011-09-01

Chiral gravity admits asymptotically AdS3 solutions that are not locally equivalent to AdS3; meaning that solutions do exist which, while obeying the strong boundary conditions usually imposed in general relativity, happen not to be Einstein spaces. In topologically massive gravity (TMG), the existence of non-Einstein solutions is particularly connected to the question about the role played by complex saddle points in the Euclidean path integral. Consequently, studying (the existence of) nonlocally AdS3 solutions to chiral gravity is relevant to understanding the quantum theory. Here, we discuss a special family of nonlocally AdS3 solutions to chiral gravity. In particular, we show that such solutions persist when one deforms the theory by adding the higher-curvature terms of the so-called new massive gravity. Moreover, the addition of higher-curvature terms to the gravity action introduces new nonlocally AdS3 solutions that have no analogues in TMG. Both stationary and time-dependent, axially symmetric solutions that asymptote AdS3 space without being locally equivalent to it appear. Defining the boundary stress tensor for the full theory, we show that these non-Einstein geometries have associated vanishing conserved charges.

Getting to the Point in Pinpoint Landing

NASA Technical Reports Server (NTRS)

1998-01-01

Assisted by Langley Research Center's Small Business Technology Transfer (STTR) Program, IntegriNautics has developed a commercialized precision landing system. The idea finds its origins in Stanford University work on a satellite test of Einstein's General Theory of Relativity, where Stanford has designed a new high-performance altitude-determining hardware.

Black Holes and the Information Paradox

NASA Astrophysics Data System (ADS)

't Hooft, Gerard

In electromagnetism, like charges repel, opposite charges attract. A remarkable feature of the gravitational force is that like masses attract. This gives rise to an instability: the more mass you have, the stronger the attractive force, until an inevitable implosion follows, leading to a "black hole". It is in the black hole where an apparent conflict between Einstein's General Relativity and the laws of Quantum Mechanics becomes manifest. Most physicists now agree that a black hole should be described by a Schrödinger equation, with a Hermitean Hamiltonian, but this requires a modification of general relativity. Both General Relativity and Quantum mechanics are shaking on their foundations.

Symmetry as Bias: Rediscovering Special Relativity

NASA Technical Reports Server (NTRS)

Lowry, Michael R.

1992-01-01

This paper describes a rational reconstruction of Einstein's discovery of special relativity, validated through an implementation: the Erlanger program. Einstein's discovery of special relativity revolutionized both the content of physics and the research strategy used by theoretical physicists. This research strategy entails a mutual bootstrapping process between a hypothesis space for biases, defined through different postulated symmetries of the universe, and a hypothesis space for physical theories. The invariance principle mutually constrains these two spaces. The invariance principle enables detecting when an evolving physical theory becomes inconsistent with its bias, and also when the biases for theories describing different phenomena are inconsistent. Structural properties of the invariance principle facilitate generating a new bias when an inconsistency is detected. After a new bias is generated. this principle facilitates reformulating the old, inconsistent theory by treating the latter as a limiting approximation. The structural properties of the invariance principle can be suitably generalized to other types of biases to enable primal-dual learning.

Nonmetricity formulation of general relativity and its scalar-tensor extension

NASA Astrophysics Data System (ADS)

Järv, Laur; Rünkla, Mihkel; Saal, Margus; Vilson, Ott

2018-06-01

Einstein's celebrated theory of gravitation can be presented in three forms: general relativity, teleparallel gravity, and the rarely considered before symmetric teleparallel gravity. Extending the latter, we introduce a new class of theories where a scalar field is coupled nonminimally to nonmetricity Q , which here encodes the gravitational effects like curvature R in general relativity or torsion T in teleparallel gravity. We point out the similarities and differences with analogous scalar-curvature and scalar-torsion theories by discussing the field equations, role of connection, conformal transformations, relation to f (Q ) theory, and cosmology. The equations for a spatially flat universe coincide with those of teleparallel dark energy, thus allowing us to explain accelerating expansion.

Mass loss due to gravitational waves with Λ > 0

NASA Astrophysics Data System (ADS)

Saw, Vee-Liem

2017-07-01

The theoretical basis for the energy carried away by gravitational waves that an isolated gravitating system emits was first formulated by Hermann Bondi during the ’60s. Recent findings from the observation of distant supernovae revealed that the rate of expansion of our universe is accelerating, which may be well explained by sticking a positive cosmological constant into the Einstein field equations for general relativity. By solving the Newman-Penrose equations (which are equivalent to the Einstein field equations), we generalize this notion of Bondi mass-energy and thereby provide a firm theoretical description of how an isolated gravitating system loses energy as it radiates gravitational waves, in a universe that expands at an accelerated rate. This is in line with the observational front of LIGO’s first announcement in February 2016 that gravitational waves from the merger of a binary black hole system have been detected.

Unified theory of nonlinear electrodynamics and gravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Torres-Gomez, Alexander; Krasnov, Kirill; Scarinci, Carlos

2011-01-15

We describe a class of unified theories of electromagnetism and gravity. The Lagrangian is of the BF type, with a potential for the B field, the gauge group is U(2) (complexified). Given a choice of the potential function the theory is a deformation of (complex) general relativity and electromagnetism, and describes just two propagating polarizations of the graviton and two of the photon. When gravity is switched off the theory becomes the usual nonlinear electrodynamics with a general structure function. The Einstein-Maxwell theory can be recovered by sending some of the parameters of the defining potential to zero, but formore » any generic choice of the potential the theory is indistinguishable from Einstein-Maxwell at low energies. A real theory is obtained by imposing suitable reality conditions. We also study the spherically-symmetric solution and show how the usual Reissner-Nordstrom solution is recovered.« less

Strong binary pulsar constraints on Lorentz violation in gravity.

PubMed

Yagi, Kent; Blas, Diego; Yunes, Nicolás; Barausse, Enrico

2014-04-25

Binary pulsars are excellent laboratories to test the building blocks of Einstein's theory of general relativity. One of these is Lorentz symmetry, which states that physical phenomena appear the same for all inertially moving observers. We study the effect of violations of Lorentz symmetry in the orbital evolution of binary pulsars and find that it induces a much more rapid decay of the binary's orbital period due to the emission of dipolar radiation. The absence of such behavior in recent observations allows us to place the most stringent constraints on Lorentz violation in gravity, thus verifying one of the cornerstones of Einstein's theory much more accurately than any previous gravitational observation.

A conformal approach for the analysis of the non-linear stability of radiation cosmologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luebbe, Christian, E-mail: c.luebbe@ucl.ac.uk; Department of Mathematics, University of Leicester, University Road, LE1 8RH; Valiente Kroon, Juan Antonio, E-mail: j.a.valiente-kroon@qmul.ac.uk

2013-01-15

The conformal Einstein equations for a trace-free (radiation) perfect fluid are derived in terms of the Levi-Civita connection of a conformally rescaled metric. These equations are used to provide a non-linear stability result for de Sitter-like trace-free (radiation) perfect fluid Friedman-Lemaitre-Robertson-Walker cosmological models. The solutions thus obtained exist globally towards the future and are future geodesically complete. - Highlights: Black-Right-Pointing-Pointer We study the Einstein-Euler system in General Relativity using conformal methods. Black-Right-Pointing-Pointer We analyze the structural properties of the associated evolution equations. Black-Right-Pointing-Pointer We establish the non-linear stability of pure radiation cosmological models.

A new golden age: testing general relativity with cosmology.

PubMed

Bean, Rachel; Ferreira, Pedro G; Taylor, Andy

2011-12-28

Gravity drives the evolution of the Universe and is at the heart of its complexity. Einstein's field equations can be used to work out the detailed dynamics of space and time and to calculate the emergence of large-scale structure in the distribution of galaxies and radiation. Over the past few years, it has become clear that cosmological observations can be used not only to constrain different world models within the context of Einstein gravity but also to constrain the theory of gravity itself. In this article, we look at different aspects of this new field in which cosmology is used to test theories of gravity with a wide range of observations.

Perfect fluids in the Einstein-Cartan theory

NASA Technical Reports Server (NTRS)

Ray, J. R.; Smalley, L. J.

1982-01-01

It is pointed out that whereas most of the discussion of the Einstein-Cartan (EC) theory involves the relationship between gravitation and elementary particles, it is possible that the theory, if correct, may be important in certain extreme astrophysical and cosmological problems. The latter would include something like the collapse of a spinning star or an early universe with spin. A set of equations that describe a macroscopic perfect fluid in the EC theory is derived and examined. The equations are derived starting from the fundamental variational principle for a perfect fluid in general relativity. A brief review of the study by Ray (1972) is included, and the results for the EC theory are presented.

REVIEWS OF TOPICAL PROBLEMS: Experimental tests of general relativity: recent progress and future directions

NASA Astrophysics Data System (ADS)

Turyshev, S. G.

2009-01-01

Einstein's general theory of relativity is the standard theory of gravity, especially where the needs of astronomy, astrophysics, cosmology, and fundamental physics are concerned. As such, this theory is used for many practical purposes involving spacecraft navigation, geodesy, and time transfer. We review the foundations of general relativity, discuss recent progress in tests of relativistic gravity, and present motivations for the new generation of high-accuracy tests of new physics beyond general relativity. Space-based experiments in fundamental physics are presently capable of uniquely addressing important questions related to the fundamental laws of nature. We discuss the advances in our understanding of fundamental physics that are anticipated in the near future and evaluate the discovery potential of a number of recently proposed space-based gravitational experiments.

Unimodular Einstein-Cartan gravity: Dynamics and conservation laws

NASA Astrophysics Data System (ADS)

Bonder, Yuri; Corral, Cristóbal

2018-04-01

Unimodular gravity is an interesting approach to address the cosmological constant problem, since the vacuum energy density of quantum fields does not gravitate in this framework, and the cosmological constant appears as an integration constant. These features arise as a consequence of considering a constrained volume element 4-form that breaks the diffeomorphisms invariance down to volume preserving diffeomorphisms. In this work, the first-order formulation of unimodular gravity is presented by considering the spin density of matter fields as a source of spacetime torsion. Even though the most general matter Lagrangian allowed by the symmetries is considered, dynamical restrictions arise on their functional dependence. The field equations are obtained and the conservation laws associated with the symmetries are derived. It is found that, analogous to torsion-free unimodular gravity, the field equation for the vierbein is traceless; nevertheless, torsion is algebraically related to the spin density as in standard Einstein-Cartan theory. The particular example of massless Dirac spinors is studied, and comparisons with standard Einstein-Cartan theory are shown.

Einstein Universe Revisited and End of Dark ERA

NASA Astrophysics Data System (ADS)

Nurgaliev, Ildus S.

2015-01-01

Historically the earliest general relativistic cosmological solution was received by Einstein himself as homogenous, isotropic one. In accordance with European cosmology it was expected static. The Eternal Universe as scientific model is conflicting with the existed theological model of the Universe created by God, therefore, of the limited age. Christianity, younger Islam, older Judaism are based on creationism. Much older oriental traditions such us Hinduism and Buddhism are based on conceptions of eternal and cyclic Universe which are closer to scientific worldview. To have static universe Einstein needed a factor to counteract gravity and postulated cosmological term and considered it as a disadvantage of the theory. This aesthetic dissatisfaction was amplified by interpretation distance-redshift relationship as a cosmological expansion effect. Emerged scientific cosmological community (excluding Hubble himself - almost always) endorsed the concept of expanding Universe. At the same time, as it is shown in this report, a natural well known factors do exist to counteract gravity. They are inertial centrifugal and Coriolis forces finding their geometrical presentation in the relativity theory.

New non-naturally reductive Einstein metrics on exceptional simple Lie groups

NASA Astrophysics Data System (ADS)

Chen, Huibin; Chen, Zhiqi; Deng, Shaoqiang

2018-01-01

In this article, we construct several non-naturally reductive Einstein metrics on exceptional simple Lie groups, which are found through the decomposition arising from generalized Wallach spaces. Using the decomposition corresponding to the two involutions, we calculate the non-zero coefficients in the formulas of the components of Ricci tensor with respect to the given metrics. The Einstein metrics are obtained as solutions of a system of polynomial equations, which we manipulate by symbolic computations using Gröbner bases. In particular, we discuss the concrete numbers of non-naturally reductive Einstein metrics for each case up to isometry and homothety.

Einstein Session of the Pontifical Academy.

ERIC Educational Resources Information Center

Science, 1980

1980-01-01

The texts of four speeches, given at the 1979 Einstein Session of the Pontifical Academy held in Rome, are presented. Each address relates to some aspect of the life and times of Albert Einstein. (SA)

On the `simple' form of the gravitational action and the self-interacting graviton

NASA Astrophysics Data System (ADS)

Tomboulis, E. T.

2017-09-01

The so-called ΓΓ-form of the gravitational Lagrangian, long known to provide its most compact expression as well as the most efficient generation of the graviton vertices, is taken as the starting point for discussing General Relativity as a theory of the self-interacting graviton. A straightforward but general method of converting to a covariant formulation by the introduction of a reference metric is given. It is used to recast the Einstein field equation as the equation of motion of a spin-2 particle interacting with the canonical energy-momentum tensor symmetrized by the standard Belinfante method applicable to any field carrying nonzero spin. This represents the graviton field equation in a form complying with the precepts of standard field theory. It is then shown how representations based on other, at face value completely unrelated definitions of energy-momentum (pseudo)tensors are all related by the addition of appropriate superpotential terms. Specifically, the superpotentials are explicitly constructed which connect to: i) the common definition consisting simply of the nonlinear part of the Einstein tensor; ii) the Landau-Lifshitz definition.

Rotating black holes in the teleparallel equivalent of general relativity

NASA Astrophysics Data System (ADS)

Nashed, Gamal G. L.

2016-05-01

We derive set of solutions with flat transverse sections in the framework of a teleparallel equivalent of general relativity which describes rotating black holes. The singularities supported from the invariants of torsion and curvature are explained. We investigate that there appear more singularities in the torsion scalars than in the curvature ones. The conserved quantities are discussed using Einstein-Cartan geometry. The physics of the constants of integration is explained through the calculations of conserved quantities. These calculations show that there is a unique solution that may describe true physical black hole.

Possible experiment with two counter-orbiting drag-free satellites to obtain a new test of Einstein's general theory of relativity and improved measurements in geodesy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Patten, R.A.; Everitt, C.W.F.

1976-03-22

In 1918, Lense and Thirring calculated that a moon orbiting a rotating planet would experience a nodal dragging effect due to general relativity. We describe an experiment to measure this effect to 1% with two counter-orbiting drag-free satellites in polar earth orbit. In addition to tracking data from existing ground stations, satellite-to-satellite Doppler ranging data are taken near the poles. New geophysical information is inherent in the polar data. (AIP)

Bose-Einstein condensation. Twenty years after

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bagnato, V. S.; Frantzeskakis, D. J.; Kevrekidis, P. G.

The aim of this introductory article is two-fold. First, we aim to offer a general introduction to the theme of Bose-Einstein condensates, and briefly discuss the evolution of a number of relevant research directions during the last two decades. Second, we introduce and present the articles that appear in this Special Volume of Romanian Reports in Physics celebrating the conclusion of the second decade since the experimental creation of Bose-Einstein condensation in ultracold gases of alkali-metal atoms.

PEOPLE IN PHYSICS: Albert Einstein's personal papers: a physics teaching resource

NASA Astrophysics Data System (ADS)

Derman, Samuel

2000-01-01

The concept of `Einstein the man' is put forward as a way of generating interest in the study of physics amongst students. Einstein provides an instantly recognizable face for science and thus a gateway into the subject through discussion of the man. Supporting this is the great volume of archive material which is available to students, teachers and the general public and in particular the archives of the Jewish National & University Library in Jerusalem.

Bose-Einstein condensation. Twenty years after

DOE PAGES

Bagnato, V. S.; Frantzeskakis, D. J.; Kevrekidis, P. G.; ...

2015-02-23

The aim of this introductory article is two-fold. First, we aim to offer a general introduction to the theme of Bose-Einstein condensates, and briefly discuss the evolution of a number of relevant research directions during the last two decades. Second, we introduce and present the articles that appear in this Special Volume of Romanian Reports in Physics celebrating the conclusion of the second decade since the experimental creation of Bose-Einstein condensation in ultracold gases of alkali-metal atoms.

The Confrontation between General Relativity and Experiment.

PubMed

Will, Clifford M

2006-01-01

The status of experimental tests of general relativity and of theoretical frameworks for analyzing them is reviewed. Einstein's equivalence principle (EEP) is well supported by experiments such as the Eötvös experiment, tests of special relativity, and the gravitational redshift experiment. Ongoing tests of EEP and of the inverse square law are searching for new interactions arising from unification or quantum gravity. Tests of general relativity at the post-Newtonian level have reached high precision, including the light deflection, the Shapiro time delay, the perihelion advance of Mercury, and the Nordtvedt effect in lunar motion. Gravitational wave damping has been detected in an amount that agrees with general relativity to better than half a percent using the Hulse-Taylor binary pulsar, and other binary pulsar systems have yielded other tests, especially of strong-field effects. When direct observation of gravitational radiation from astrophysical sources begins, new tests of general relativity will be possible.

The Confrontation between General Relativity and Experiment.

PubMed

Will, Clifford M

2001-01-01

The status of experimental tests of general relativity and of theoretical frameworks for analysing them are reviewed. Einstein's equivalence principle (EEP) is well supported by experiments such as the Eötvös experiment, tests of special relativity, and the gravitational redshift experiment. Future tests of EEP and of the inverse square law will search for new interactions arising from unification or quantum gravity. Tests of general relativity at the post-Newtonian level have reached high precision, including the light defl ection the Shapiro time delay, the perihelion advance of Mercury, and the Nordtvedt effect in lunar motion. Gravitational wave damping has been detected in an amount that agrees with general relativity to half a percent using the Hulse-Taylor binary pulsar, and new binary pulsar systems may yield further improvements. When direct observation of gravitational radiation from astrophysical sources begins, new tests of general relativity will be possible.

Inhomogeneous Einstein-Rosen string cosmology

NASA Astrophysics Data System (ADS)

Clancy, Dominic; Feinstein, Alexander; Lidsey, James E.; Tavakol, Reza

1999-08-01

Families of anisotropic and inhomogeneous string cosmologies containing non-trivial dilaton and axion fields are derived by applying the global symmetries of the string effective action to a generalized Einstein-Rosen metric. The models exhibit a two-dimensional group of Abelian isometries. In particular, two classes of exact solutions are found that represent inhomogeneous generalizations of the Bianchi type VIh cosmology. The asymptotic behavior of the solutions is investigated and further applications are briefly discussed.

Conversations With Albert Einstein. II

ERIC Educational Resources Information Center

Shankland, R. S.

1973-01-01

Discusses Einstein's views on the role of Michelson-Morley, Fizeau, and Miller experiments in the development of relativity and his attitude toward the theories of new quantum mechanics. Indicates that Einstein's opposition to quantum mechanics is beyond dispute. (CC)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khodam-Mohammadi, A.; Monshizadeh, M.

We give a review of the existence of Taub-NUT/bolt solutions in Einstein Gauss-Bonnet gravity with the parameter {alpha} in six dimensions. Although the spacetime with base space S{sup 2}xS{sup 2} has a curvature singularity at r=N, which does not admit NUT solutions, we may proceed with the same computations as in the CP{sup 2} case. The investigation of thermodynamics of NUT/bolt solutions in six dimensions is carried out. We compute the finite action, mass, entropy, and temperature of the black hole. Then the validity of the first law of thermodynamics is demonstrated. It is shown that in NUT solutions allmore » thermodynamic quantities for both base spaces are related to each other by substituting {alpha}{sup CP{sup k}}=[(k+1)/k]{alpha}{sup S{sup 2}}{sup xS{sup 2}}{sup x...S{sub k}{sup 2}}. So, no further information is given by investigating NUT solutions in the S{sup 2}xS{sup 2} case. This relation is not true for bolt solutions. A generalization of the thermodynamics of black holes to arbitrary even dimensions is made using a new method based on the Gibbs-Duhem relation and Gibbs free energy for NUT solutions. According to this method, the finite action in Einstein Gauss-Bonnet is obtained by considering the generalized finite action in Einstein gravity with an additional term as a function of {alpha}. Stability analysis is done by investigating the heat capacity and entropy in the allowed range of {alpha}, {lambda}, and N. For NUT solutions in d dimensions, there exists a stable phase at a narrow range of {alpha}. In six-dimensional bolt solutions, the metric is completely stable for B=S{sup 2}xS{sup 2} and is completely unstable for the B=CP{sup 2} case.« less

New Frontiers at the Interface of General Relativity and Quantum Optics

NASA Astrophysics Data System (ADS)

Feiler, C.; Buser, M.; Kajari, E.; Schleich, W. P.; Rasel, E. M.; O'Connell, R. F.

2009-12-01

In the present paper we follow three major themes: (i) concepts of rotation in general relativity, (ii) effects induced by these generalized rotations, and (iii) their measurement using interferometry. Our journey takes us from the Foucault pendulum via the Sagnac interferometer to manifestations of gravito-magnetism in double binary pulsars and in Gödel’s Universe. Throughout our article we emphasize the emerging role of matter wave interferometry based on cold atoms or Bose-Einstein condensates leading to superior inertial sensors. In particular, we advertise recent activities directed towards the operation of a coherent matter wave interferometer in an extended free fall.

General flat four-dimensional world pictures and clock systems

NASA Technical Reports Server (NTRS)

Hsu, J. P.; Underwood, J. A.

1978-01-01

We explore the mathematical structure and the physical implications of a general four-dimensional symmetry framework which is consistent with the Poincare-Einstein principle of relativity for physical laws and with experiments. In particular, we discuss a four-dimensional framework in which all observers in different frames use one and the same grid of clocks. The general framework includes special relativity and a recently proposed new four-dimensional symmetry with a nonuniversal light speed as two special simple cases. The connection between the properties of light propagation and the convention concerning clock systems is also discussed, and is seen to be nonunique within the four-dimensional framework.

Why did Einstein reject the November tensor in 1912-1913, only to come back to it in November 1915?

NASA Astrophysics Data System (ADS)

Weinstein, Galina

2018-05-01

The question of Einstein's rejection of the November tensor is re-examined in light of conflicting answers by several historians. I discuss these conflicting conjectures in view of three questions that should inform our thinking: Why did Einstein reject the November tensor in 1912, only to come back to it in 1915? Why was it hard for Einstein to recognize that the November tensor is a natural generalization of Newton's law of gravitation? Why did it take him three years to realize that the November tensor is not incompatible with Newton's law? I first briefly describe Einstein's work in the Zurich Notebook. I then discuss a number of interpretive conjectures formulated by historians and what may be inferred from them. Finally, I offer a new combined conjecture that answers the above questions.

Einstein as a Missionary of Science

NASA Astrophysics Data System (ADS)

Renn, Jürgen

2013-10-01

The paper reviews Einstein's engagement as a mediator and popularizer of science. It discusses the formative role of popular scientific literature for the young Einstein, showing that not only his broad scientific outlook but also his internationalist political views were shaped by these readings. Then, on the basis of recent detailed studies, Einstein's travels and their impact on the dissemination of relativity theory are examined. These activities as well as Einstein's own popular writings are interpreted in the context of his understanding of science as part of human culture.

Einstein 1905-1955: His Approach to Physics

NASA Astrophysics Data System (ADS)

Damour, Thibault

We review Einstein's epistemological conceptions, and indicate their philosophical roots. The particular importance of the ideas of Hume, Kant, Mach, and Poincaré is highlighted. The specific characteristics of Einstein's approach to physics are underlined. Lastly, we consider the practical application of Einstein's methodological principles to the two theories of relativity, and to quantum theory. We emphasize a Kantian approach to quantum theory.

Simon Newcomb: America's Unofficial Astronomer Royal

NASA Astrophysics Data System (ADS)

Graham, John

2007-10-01

Bill Carter and Merri Sue Carter Mantazas; xiii + 213 pp.; ISBN 1-59113-803-5 2006; $26.95 This book introduced me to a commanding figure in American science from the late nineteenth century: Simon Newcomb. Newcomb has been called the nineteenth-century equivalent of Carl Sagan and Albert Einstein. He rose from humble beginnings to be the preeminent American astronomer of his generation. He made basic, far-reaching, and enduring contributions to positional astronomy and planetary dynamics. On the more practical side, he determined a remarkably accurate value for the velocity of light, one within 0.01% of the value accepted today. His work provided an experimental grounding for the special and general theories of relativity to be formulated by Einstein in the coming twentieth century.

Measurement incompatibility and Schrödinger-Einstein-Podolsky-Rosen steering in a class of probabilistic theories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Banik, Manik, E-mail: manik11ju@gmail.com

Steering is one of the most counter intuitive non-classical features of bipartite quantum system, first noticed by Schrödinger at the early days of quantum theory. On the other hand, measurement incompatibility is another non-classical feature of quantum theory, initially pointed out by Bohr. Recently, Quintino et al. [Phys. Rev. Lett. 113, 160402 (2014)] and Uola et al. [Phys. Rev. Lett. 113, 160403 (2014)] have investigated the relation between these two distinct non-classical features. They have shown that a set of measurements is not jointly measurable (i.e., incompatible) if and only if they can be used for demonstrating Schrödinger-Einstein-Podolsky-Rosen steering. Themore » concept of steering has been generalized for more general abstract tensor product theories rather than just Hilbert space quantum mechanics. In this article, we discuss that the notion of measurement incompatibility can be extended for general probability theories. Further, we show that the connection between steering and measurement incompatibility holds in a border class of tensor product theories rather than just quantum theory.« less

Quantum Landau damping in dipolar Bose-Einstein condensates

NASA Astrophysics Data System (ADS)

Mendonça, J. T.; Terças, H.; Gammal, A.

2018-06-01

We consider Landau damping of elementary excitations in Bose-Einstein condensates (BECs) with dipolar interactions. We discuss quantum and quasiclassical regimes of Landau damping. We use a generalized wave-kinetic description of BECs which, apart from the long-range dipolar interactions, also takes into account the quantum fluctuations and the finite-energy corrections to short-range interactions. Such a description is therefore more general than the usual mean-field approximation. The present wave-kinetic approach is well suited for the study of kinetic effects in BECs, such as those associated with Landau damping, atom trapping, and turbulent diffusion. The inclusion of quantum fluctuations and energy corrections changes the dispersion relation and the damping rates, leading to possible experimental signatures of these effects. Quantum Landau damping is described with generality, and particular examples of dipolar condensates in two and three dimensions are studied. The occurrence of roton-maxon excitations, and their relevance to Landau damping, are also considered in detail. The present approach is mainly based on a linear perturbative procedure, but the nonlinear regime of Landau damping, which includes atom trapping and atom diffusion, is also briefly discussed.

String Theory: Big Problem for Small Size

ERIC Educational Resources Information Center

Sahoo, S.

2009-01-01

String theory is the most promising candidate theory for a unified description of all the fundamental forces that exist in nature. It provides a mathematical framework that combines quantum theory with Einstein's general theory of relativity. The typical size of a string is of the order of 10[superscript -33] cm, called the Planck length. But due…

Why Do Things Fall? How to Explain Why Gravity Is Not a Force

ERIC Educational Resources Information Center

Stannard, Warren B.

2018-01-01

In most high school physics classes, gravity is described as an attractive force between two masses as formulated by Newton over 300 years ago. Einstein's general theory of relativity implies that gravitational effects are instead the result of a "curvature" of space-time. However, explaining why things fall without resorting to Newton's…

Interactive Visualization of a Thin Disc around a Schwarzschild Black Hole

ERIC Educational Resources Information Center

Muller, Thomas; Frauendiener, Jorg

2012-01-01

In a first course in general relativity, the Schwarzschild spacetime is the most discussed analytic solution to Einstein's field equations. Unfortunately, there is rarely enough time to study the optical consequences of the bending of light for some advanced examples. In this paper, we present how the visual appearance of a thin disc around a…

Geometry as an Object of Experience: The Missed Debate between Poincare and Einstein

ERIC Educational Resources Information Center

Hacyan, Shahen

2009-01-01

According to Poincare, a geometry cannot be an object of experience since any geometrical experiment must be realized with physical objects, such as rulers and light rays, and it is only their properties that can be tested. This position was apparently refuted by general relativity and the successful confirmation of its predictions by astronomical…

Bose-Einstein distribution of money in a free-market economy. II

NASA Astrophysics Data System (ADS)

Kürten, K. E.; Kusmartsev, F. V.

2011-01-01

We argue about the application of methods of statistical mechanics to free economy (Kusmartsev F. V., Phys. Lett. A, 375 (2011) 966) and find that the most general distribution of money or income in a free-market economy has a general Bose-Einstein distribution form. Therewith the market is described by three parameters: temperature, chemical potential and the space dimensionality. Numerical simulations and a detailed analysis of a generic model confirm this finding.

An Exact Solution of Einstein-Maxwell Gravity Coupled to a Scalar Field

NASA Technical Reports Server (NTRS)

Turyshev, S. G.

1995-01-01

The general solution to low-energy string theory representing static spherically symmetric solution of the Einstein-Maxwell gravity with a massless scalar field has been found. Some of the partial cases appear to coincide with known solutions to black holes, naked singularities, and gravity and electromagnetic fields.

Gravitational Waves from Isolated Systems: Surprising Consequences of a Positive Cosmological Constant.

PubMed

Ashtekar, Abhay; Bonga, Béatrice; Kesavan, Aruna

2016-02-05

There is a deep tension between the well-developed theory of gravitational waves from isolated systems and the presence of a positive cosmological constant Λ, however tiny. In particular a generalization of Einstein's 1918 quadrupole formula that would allow a positive Λ is not yet available. We first explain the principal difficulties and then show that it is possible to overcome them in the weak field limit. These results also provide concrete hints for constructing the Λ>0 generalization of the Bondi-Sachs framework for full, nonlinear general relativity.

Gravitational Waves from Isolated Systems: Surprising Consequences of a Positive Cosmological Constant

NASA Astrophysics Data System (ADS)

Ashtekar, Abhay; Bonga, Béatrice; Kesavan, Aruna

2016-02-01

There is a deep tension between the well-developed theory of gravitational waves from isolated systems and the presence of a positive cosmological constant Λ , however tiny. In particular a generalization of Einstein's 1918 quadrupole formula that would allow a positive Λ is not yet available. We first explain the principal difficulties and then show that it is possible to overcome them in the weak field limit. These results also provide concrete hints for constructing the Λ >0 generalization of the Bondi-Sachs framework for full, nonlinear general relativity.

On Einstein, Light Quanta, Radiation, and Relativity in 1905

ERIC Educational Resources Information Center

Miller, Arthur I.

1976-01-01

Analyzes section 8 of Einstein's relativity paper of 1905, "On the Electrodynamics of Moving Bodies," in its historical context. Relates this section to the rest of the relativity paper, to the genesis of relativity theory, and to contemporaneous work on radiation theory. (Author/MLH)

Breakdown of the Stokes-Einstein Relation for the Rotational Diffusivity of Polymer Grafted Nanoparticles in Polymer Melts.

PubMed

Maldonado-Camargo, Lorena; Rinaldi, Carlos

2016-11-09

We report observations of breakdown of the Stokes-Einstein relation for the rotational diffusivity of polymer-grafted spherical nanoparticles in polymer melts. The rotational diffusivity of magnetic nanoparticles coated with poly(ethylene glycol) dispersed in poly(ethylene glycol) melts was determined through dynamic magnetic susceptibility measurements of the collective rotation of the magnetic nanoparticles due to imposed time-varying magnetic torques. These measurements clearly demonstrate the existence of a critical molecular weight for the melt polymer, below which the Stokes-Einstein relation accurately describes the rotational diffusivity of the polymer-grafted nanoparticles and above which the Stokes-Einstein relation ceases to apply. This critical molecular weight was found to correspond to a chain contour length that approximates the hydrodynamic diameter of the nanoparticles.

Vacuum stress energy density and its gravitational implications

NASA Astrophysics Data System (ADS)

Estrada, Ricardo; Fulling, Stephen A.; Kaplan, Lev; Kirsten, Klaus; Liu, Zhonghai; Milton, Kimball A.

2008-04-01

In nongravitational physics the local density of energy is often regarded as merely a bookkeeping device; only total energy has an experimental meaning—and it is only modulo a constant term. But in general relativity the local stress-energy tensor is the source term in Einstein's equation. In closed universes, and those with Kaluza-Klein dimensions, theoretical consistency demands that quantum vacuum energy should exist and have gravitational effects, although there are no boundary materials giving rise to that energy by van der Waals interactions. In the lab there are boundaries, and in general the energy density has a nonintegrable singularity as a boundary is approached (for idealized boundary conditions). As pointed out long ago by Candelas and Deutsch, in this situation there is doubt about the viability of the semiclassical Einstein equation. Our goal is to show that the divergences in the linearized Einstein equation can be renormalized to yield a plausible approximation to the finite theory that presumably exists for realistic boundary conditions. For a scalar field with Dirichlet or Neumann boundary conditions inside a rectangular parallelepiped, we have calculated by the method of images all components of the stress tensor, for all values of the conformal coupling parameter and an exponential ultraviolet cutoff parameter. The qualitative features of contributions from various classes of closed classical paths are noted. Then the Estrada-Kanwal distributional theory of asymptotics, particularly the moment expansion, is used to show that the linearized Einstein equation with the stress-energy near a plane boundary as source converges to a consistent theory when the cutoff is removed. This paper reports work in progress on a project combining researchers in Texas, Louisiana and Oklahoma. It is supported by NSF Grants PHY-0554849 and PHY-0554926.

Equivalent off-diagonal cosmological models and ekpyrotic scenarios in -modified, massive, and einstein gravity

NASA Astrophysics Data System (ADS)

Vacaru, Sergiu I.

2015-04-01

We reinvestigate how generic off-diagonal cosmological solutions depending, in general, on all spacetime coordinates can be constructed in massive and -modified gravity using the anholonomic frame deformation method. New classes of locally anisotropic and (in-) homogeneous cosmological metrics are constructed with open and closed spatial geometries. By resorting to such solutions, we show that they describe the late time acceleration due to effective cosmological terms induced by nonlinear off-diagonal interactions, possible modifications of the gravitational action and graviton mass. The cosmological metrics and related Stückelberg fields are constructed in explicit form up to nonholonomic frame transforms of the Friedmann-Lamaître-Robertson-Walker (FLRW) coordinates. The solutions include matter, graviton mass, and other effective sources modeling nonlinear gravitational and matter field interactions with polarization of physical constants and deformations of metrics, which may explain dark energy and dark matter effects. However, we argue that it is not always necessary to modify gravity if we consider the effective generalized Einstein equations with nontrivial vacuum and/or non-minimal coupling with matter. Indeed, we state certain conditions when such configurations mimic interesting solutions in general relativity and modifications, for instance, when we can extract the general Painlevé-Gullstrand and FLRW metrics. In a more general context, we elaborate on a reconstruction procedure for off-diagonal cosmological solutions which describe cyclic and ekpyrotic universes. Finally, open issues and further perspectives are discussed.

Covariant Conformal Decomposition of Einstein Equations

NASA Astrophysics Data System (ADS)

Gourgoulhon, E.; Novak, J.

It has been shown1,2 that the usual 3+1 form of Einstein's equations may be ill-posed. This result has been previously observed in numerical simulations3,4. We present a 3+1 type formalism inspired by these works to decompose Einstein's equations. This decomposition is motivated by the aim of stable numerical implementation and resolution of the equations. We introduce the conformal 3-``metric'' (scaled by the determinant of the usual 3-metric) which is a tensor density of weight -2/3. The Einstein equations are then derived in terms of this ``metric'', of the conformal extrinsic curvature and in terms of the associated derivative. We also introduce a flat 3-metric (the asymptotic metric for isolated systems) and the associated derivative. Finally, the generalized Dirac gauge (introduced by Smarr and York5) is used in this formalism and some examples of formulation of Einstein's equations are shown.

Characteristics of sediment transport at selected sites along the Missouri River, 2011–12

USGS Publications Warehouse

Rus, David L.; Galloway, Joel M.; Alexander, Jason S.

2015-10-22

The Modified-Einstein Procedure tended to predict greater total-sediment loads when compared to measured values. These differences may be the result of sediment deficits in the Missouri River that lead to an overprediction by the Modified-Einstein Procedure, the unsampled zone above the streambed that leads to an underprediction by the suspended sampler, or general uncertainty in the sampling approach. The differences between total-sediment load obtained through measurements and that estimated from applied theoretical procedures such as the Modified-Einstein Procedure pose a challenge for reliably characterizing total-sediment transport. Though it is not clear which of the two techniques is more accurate, the general tendency of the two to be within an order of magnitude of one another may be adequate for many sediment studies.

Double-black-hole solutions of the Einstein-Maxwell-dilaton theory in five dimensions

NASA Astrophysics Data System (ADS)

Stelea, Cristian

2018-01-01

We describe a solution-generating technique that maps a static charged solution of the Einstein-Maxwell theory in four (or five) dimensions to a five-dimensional solution of the Einstein-Maxwell-Dilaton theory. As examples of this technique first we show how to construct the dilatonic version of the Reissner-Nordström solution in five dimensions and then we consider the more general case of the double black hole solutions and describe some of their properties. We found that in the general case the value of the conical singularities in between the black holes is affected by the dilaton's coupling constant to the gauge field and only in the particular case when all charges are proportional to the masses this dependence cancels out.

Einstein's Cosmos (German Title: Einsteins Kosmos)

NASA Astrophysics Data System (ADS)

Duerbeck, Hilmar W.; Dick, Wolfgang R.

The different contributions of the present volume illuminate the interaction between Einstein and his colleagues when the foundations of modern cosmology were laid: First, the relativistic effects in the solar system, the gravitational redshift in the solar spectrum, and Einstein's relations with Freundlich and Eddington. Second, the cosmological models of Einstein, de Sitter, Friedmann, and Lemaître, which were discussed controversely till the end of the 1920s. Other scientists have also widened or critically questioned Einstein's insight and knowledge: Schwarzschild, Selety, Silberstein, and Mandl, whose life and work is discussed in separate articles. In those days, politics more than ever in history had influenced the lifes of scientists. Therefore, some comments on the ``political cosmos'' that has influenced decisively Einstein's life are also given. A special role in popularizing Einstein's world view was played by Archenhold Observatory in Berlin. A list of Einstein memorial places and a bibliographic list conclude the present book. All papers are written in German, and have English abstracts.

Solar physics in Potsdam. (German Title: Sonnenphysik in Potsdam)

NASA Astrophysics Data System (ADS)

Staude, Jürgen

Solar research initiated the establishment of the Astrophysical Observatory Potsdam (AOP) in 1874. The present contribution outlines the development of solar physics in Potsdam from the early history of the AOP to this day. The main topics are the work of Karl Schwarzschild, the investigations related to the general theory of relativity, the foundation of the Einstein tower, Walter Grotrian's founding of modern coronal physics, and the investigations of sunspot magnetic fields.

It’s About Time -- Understanding China’s Strategic Patience

DTIC Science & Technology

2012-03-18

Einstein and Stephen 3 Hawking, made conceptualizing time easier to accept by linking time with space. Time and space are inherently linked together...same regardless of how you were moving - exactly as experiments and mathematics of the day showed them to be. In 1905, Albert Einstein published...speeds relative to each other. Einstein explained that when two objects are moving at independent constant speeds, emphasizing the relative motion

Variation of fundamental constants on sub- and super-Hubble scales: From the equivalence principle to the multiverse

NASA Astrophysics Data System (ADS)

Uzan, Jean-Philippe

2013-02-01

Fundamental constants play a central role in many modern developments in gravitation and cosmology. Most extensions of general relativity lead to the conclusion that dimensionless constants are actually dynamical fields. Any detection of their variation on sub-Hubble scales would signal a violation of the Einstein equivalence principle and hence a lead to gravity beyond general relativity. On super-Hubble scales, or maybe should we say on super-universe scales, such variations are invoked as a solution to the fine-tuning problem, in connection with an anthropic approach.

Ambitwistor formulations of R 2 gravity and ( DF)2 gauge theories

NASA Astrophysics Data System (ADS)

Azevedo, Thales; Engelund, Oluf Tang

2017-11-01

We consider D-dimensional amplitudes in R 2 gravities (conformal gravity in D = 4) and in the recently introduced ( DF)2 gauge theory, from the perspective of the CHY formulae and ambitwistor string theory. These theories are related through the BCJ double-copy construction, and the ( DF)2 gauge theory obeys color-kinematics duality. We work out the worldsheet details of these theories and show that they admit a formulation as integrals on the support of the scattering equations, or alternatively, as ambitwistor string theories. For gravity, this generalizes the work done by Berkovits and Witten on conformal gravity to D dimensions. The ambitwistor is also interpreted as a D-dimensional generalization of Witten's twistor string (SYM + conformal supergravity). As part of our ambitwistor investigation, we discover another ( DF)2 gauge theory containing a photon that couples to Einstein gravity. This theory can provide an alternative KLT description of Einstein gravity compared to the usual Yang-Mills squared.

Bulk entanglement gravity without a boundary: Towards finding Einstein's equation in Hilbert space

NASA Astrophysics Data System (ADS)

Cao, ChunJun; Carroll, Sean M.

2018-04-01

We consider the emergence from quantum entanglement of spacetime geometry in a bulk region. For certain classes of quantum states in an appropriately factorized Hilbert space, a spatial geometry can be defined by associating areas along codimension-one surfaces with the entanglement entropy between either side. We show how radon transforms can be used to convert these data into a spatial metric. Under a particular set of assumptions, the time evolution of such a state traces out a four-dimensional spacetime geometry, and we argue using a modified version of Jacobson's "entanglement equilibrium" that the geometry should obey Einstein's equation in the weak-field limit. We also discuss how entanglement equilibrium is related to a generalization of the Ryu-Takayanagi formula in more general settings, and how quantum error correction can help specify the emergence map between the full quantum-gravity Hilbert space and the semiclassical limit of quantum fields propagating on a classical spacetime.

Cosmological Models and Stability

NASA Astrophysics Data System (ADS)

Andersson, Lars

Principles in the form of heuristic guidelines or generally accepted dogma play an important role in the development of physical theories. In particular, philosophical considerations and principles figure prominently in the work of Albert Einstein. As mentioned in the talk by Jiří Bičák at this conference, Einstein formulated the equivalence principle, an essential step on the road to general relativity, during his time in Prague 1911-1912. In this talk, I would like to discuss some aspects of cosmological models. As cosmology is an area of physics where "principles" such as the "cosmological principle" or the "Copernican principle" play a prominent role in motivating the class of models which form part of the current standard model, I will start by comparing the role of the equivalence principle to that of the principles used in cosmology. I will then briefly describe the standard model of cosmology to give a perspective on some mathematical problems and conjectures on cosmological models, which are discussed in the later part of this paper.

General Theory of Relativity: Will It Survive the Next Decade?

NASA Technical Reports Server (NTRS)

Bertolami, Orfeu; Paramos, Jorge; Turyshev, Slava G.

2006-01-01

The nature of gravity is fundamental to our understanding of our own solar system, the galaxy and the structure and evolution of the Universe. Einstein's general theory of relativity is the standard model that is used for almost ninety years to describe gravitational phenomena on these various scales. We review the foundations of general relativity, discuss the recent progress in the tests of relativistic gravity, and present motivations for high-accuracy gravitational experiments in space. We also summarize the science objectives and technology needs for the laboratory experiments in space with laboratory being the entire solar system. We discuss the advances in our understanding of fundamental physics anticipated in the near future and evaluate discovery potential for the recently proposed gravitational experiments.

About Some Regge-Like Relations for (stable) Black Holes

NASA Astrophysics Data System (ADS)

Recami, E.; Tonin-Zanchin, V.; del Popolo, A.; Gambera, M.

1997-08-01

We associated, in a classical formulation of "strong gravity", hadron constituents with suitable stationary, axisymmetric solutions of some new Einstein-type equations supposed to describe the strong field inside hadrons. These new equations can be obtained by the Einstein equations with cosmological term Lambda. As a consequence, Lambda and the masses M result in our theory to be scaled up, and transformed into a "hadronic constant" and into "strong masses", respectively. Due to the unusual range of Lambda and M values considered, we met a series of solutions of the Kerr-Newman-de Sitter (hereafter KNdS) type with rather interesting properties. The requirement that those solutions be stable, i.e., that their temperature (or surface gravity) be vanishingly small, implies the coincidence of at least two of their (in general, three) horizons. Imposing the stability condition of a certain horizon does yield (once chosen the values of J, q and Lambda) mass and radius of the associated black-hole (hereafter BH). In the case of ordinary Einstein equations and for stable BHs of the KNdS type, we get in particular Regge-like (hereafter RL) relations among mass M, angular momentum J, charge q and cosmological constant Lambda; which did not receive enough attention in the previous literature. Besides, we show some particular and interesting cases of these relations. Another interesting point is that, with few exceptions, all such relations (among M, J, q, Lambda) lead to solutions that can be regarded as (stable) cosmological models.

Bose-Einstein condensation of light: general theory.

PubMed

Sob'yanin, Denis Nikolaevich

2013-08-01

A theory of Bose-Einstein condensation of light in a dye-filled optical microcavity is presented. The theory is based on the hierarchical maximum entropy principle and allows one to investigate the fluctuating behavior of the photon gas in the microcavity for all numbers of photons, dye molecules, and excitations at all temperatures, including the whole critical region. The master equation describing the interaction between photons and dye molecules in the microcavity is derived and the equivalence between the hierarchical maximum entropy principle and the master equation approach is shown. The cases of a fixed mean total photon number and a fixed total excitation number are considered, and a much sharper, nonparabolic onset of a macroscopic Bose-Einstein condensation of light in the latter case is demonstrated. The theory does not use the grand canonical approximation, takes into account the photon polarization degeneracy, and exactly describes the microscopic, mesoscopic, and macroscopic Bose-Einstein condensation of light. Under certain conditions, it predicts sub-Poissonian statistics of the photon condensate and the polarized photon condensate, and a universal relation takes place between the degrees of second-order coherence for these condensates. In the macroscopic case, there appear a sharp jump in the degrees of second-order coherence, a sharp jump and kink in the reduced standard deviations of the fluctuating numbers of photons in the polarized and whole condensates, and a sharp peak, a cusp, of the Mandel parameter for the whole condensate in the critical region. The possibility of nonclassical light generation in the microcavity with the photon Bose-Einstein condensate is predicted.

Integrability of geodesics and action-angle variables in Sasaki-Einstein space T^{1,1}

NASA Astrophysics Data System (ADS)

Visinescu, Mihai

2016-09-01

We briefly describe the construction of Stäkel-Killing and Killing-Yano tensors on toric Sasaki-Einstein manifolds without working out intricate generalized Killing equations. The integrals of geodesic motions are expressed in terms of Killing vectors and Killing-Yano tensors of the homogeneous Sasaki-Einstein space T^{1,1}. We discuss the integrability of geodesics and construct explicitly the action-angle variables. Two pairs of frequencies of the geodesic motions are resonant giving way to chaotic behavior when the system is perturbed.

Shear free, twisting Einstein-Maxwell metrics in the Newman-Penrose formalism

NASA Technical Reports Server (NTRS)

Lind, R. W.

1972-01-01

The problem of finding algebraically special solutions to the vacuum Einstein-Maxwell equations was investigated using a spin coefficient formalism. The general case in which the degenerate null vectors are not hypersurface orthogonal is reduced to a problem of solving five coupled differential equations that are no longer dependent on the affine parameter along the degenerate null directions. It is shown that the most general regular, shear-free, nonradiating solution to these equations is the Kerr-Newman metric.

Dynamical spacetimes in conformal gravity

NASA Astrophysics Data System (ADS)

Zhang, Hongsheng; Zhang, Yi; Li, Xin-Zhou

2017-08-01

The conformal gravity remarkably boosts our prehension of gravity theories. We find a series of dynamical solutions in the W2-conformal gravity, including generalized Schwarzschild-Friedmann-Robertson-Walker (GSFRW), charged generalized Schwarzschild-Friedmann-Robertson-Walker (CGSFRW), especially rotating Friedmann-Robertson-Walker (RFRW), charged rotating Friedmann-Robertson-Walker (CRFRW), and a dynamical cylindrically symmetric solutions. The RFRW, CRFRW and the dynamical cylindrically symmetric solutions are never found in the Einstein gravity and modified gravities. The GSFRW and CGSFRW solutions take different forms from the corresponding solutions in the Einstein gravity.

Towards a second law for Lovelock theories

NASA Astrophysics Data System (ADS)

Bhattacharyya, Sayantani; Haehl, Felix M.; Kundu, Nilay; Loganayagam, R.; Rangamani, Mukund

2017-03-01

In classical general relativity described by Einstein-Hilbert gravity, black holes behave as thermodynamic objects. In particular, the laws of black hole mechanics can be interpreted as laws of thermodynamics. The first law of black hole mechanics extends to higher derivative theories via the Noether charge construction of Wald. One also expects the statement of the second law, which in Einstein-Hilbert theory owes to Hawking's area theorem, to extend to higher derivative theories. To argue for this however one needs a notion of entropy for dynamical black holes, which the Noether charge construction does not provide. We propose such an entropy function for the family of Lovelock theories, treating the higher derivative terms as perturbations to the Einstein-Hilbert theory. Working around a dynamical black hole solution, and making no assumptions about the amplitude of departure from equilibrium, we construct a candidate entropy functional valid to all orders in the low energy effective field theory. This entropy functional satisfies a second law, modulo a certain subtle boundary term, which deserves further investigation in non-spherically symmetric situations.

Measuring Starlight Deflection during the 2017 Eclipse: Repeating the Experiment that made Einstein Famous

NASA Astrophysics Data System (ADS)

Bruns, Donald

2016-05-01

In 1919, astronomers performed an experiment during a solar eclipse, attempting to measure the deflection of stars near the sun, in order to verify Einstein's theory of general relativity. The experiment was very difficult and the results were marginal, but the success made Albert Einstein famous around the world. Astronomers last repeated the experiment in 1973, achieving an error of 11%. In 2017, using amateur equipment and modern technology, I plan to repeat the experiment and achieve a 1% error. The best available star catalog will be used for star positions. Corrections for optical distortion and atmospheric refraction are better than 0.01 arcsec. During totality, I expect 7 or 8 measurable stars down to magnitude 9.5, based on analysis of previous eclipse measurements taken by amateurs. Reference images, taken near the sun during totality, will be used for precise calibration. Preliminary test runs performed during twilight in April 2016 and April 2017 can accurately simulate the sky conditions during totality, providing an accurate estimate of the final uncertainty.

Classes of exact Einstein Maxwell solutions

NASA Astrophysics Data System (ADS)

Komathiraj, K.; Maharaj, S. D.

2007-12-01

We find new classes of exact solutions to the Einstein Maxwell system of equations for a charged sphere with a particular choice of the electric field intensity and one of the gravitational potentials. The condition of pressure isotropy is reduced to a linear, second order differential equation which can be solved in general. Consequently we can find exact solutions to the Einstein Maxwell field equations corresponding to a static spherically symmetric gravitational potential in terms of hypergeometric functions. It is possible to find exact solutions which can be written explicitly in terms of elementary functions, namely polynomials and product of polynomials and algebraic functions. Uncharged solutions are regainable with our choice of electric field intensity; in particular we generate the Einstein universe for particular parameter values.

Gravitation: Foundations and Frontiers

NASA Astrophysics Data System (ADS)

Padmanabhan, T.

2010-01-01

1. Special relativity; 2. Scalar and electromagnetic fields in special relativity; 3. Gravity and spacetime geometry: the inescapable connection; 4. Metric tensor, geodesics and covariant derivative; 5. Curvature of spacetime; 6. Einstein's field equations and gravitational dynamics; 7. Spherically symmetric geometry; 8. Black holes; 9. Gravitational waves; 10. Relativistic cosmology; 11. Differential forms and exterior calculus; 12. Hamiltonian structure of general relativity; 13. Evolution of cosmological perturbations; 14. Quantum field theory in curved spacetime; 15. Gravity in higher and lower dimensions; 16. Gravity as an emergent phenomenon; Notes; Index.

Relativity and indeterminism

NASA Astrophysics Data System (ADS)

Byrne, Patrick H.

1981-12-01

It is well known that Albert Einstein adhered to a deterministic world view throughout his career. Nevertheless, his developments of the special and general theories of relativity prove to be incompatible with that world view. Two different forms of determinism—classical Laplacian determinism and the determinism of isolated systems—are considered. Through careful considerations of what concretely is involved in predicting future states of the entire universe, or of isolated systems, it is shown that the demands of the theories of relativity make these deterministic positions untenable.

Astrophysical observations: lensing and eclipsing Einstein's theories.

PubMed

Bennett, Charles L

2005-02-11

Albert Einstein postulated the equivalence of energy and mass, developed the theory of special relativity, explained the photoelectric effect, and described Brownian motion in five papers, all published in 1905, 100 years ago. With these papers, Einstein provided the framework for understanding modern astrophysical phenomena. Conversely, astrophysical observations provide one of the most effective means for testing Einstein's theories. Here, I review astrophysical advances precipitated by Einstein's insights, including gravitational redshifts, gravitational lensing, gravitational waves, the Lense-Thirring effect, and modern cosmology. A complete understanding of cosmology, from the earliest moments to the ultimate fate of the universe, will require developments in physics beyond Einstein, to a unified theory of gravity and quantum physics.

The Confrontation between General Relativity and Experiment.

PubMed

Will, Clifford M

2014-01-01

The status of experimental tests of general relativity and of theoretical frameworks for analyzing them is reviewed and updated. Einstein's equivalence principle (EEP) is well supported by experiments such as the Eötvös experiment, tests of local Lorentz invariance and clock experiments. Ongoing tests of EEP and of the inverse square law are searching for new interactions arising from unification or quantum gravity. Tests of general relativity at the post-Newtonian level have reached high precision, including the light deflection, the Shapiro time delay, the perihelion advance of Mercury, the Nordtvedt effect in lunar motion, and frame-dragging. Gravitational wave damping has been detected in an amount that agrees with general relativity to better than half a percent using the Hulse-Taylor binary pulsar, and a growing family of other binary pulsar systems is yielding new tests, especially of strong-field effects. Current and future tests of relativity will center on strong gravity and gravitational waves.

Review of Software Platforms for Agent Based Models

DTIC Science & Technology

2008-04-01

EINSTein 4.3.2 Battlefield Python (optional, for batch runs) MANA 4.3.3 Battlefield N/A MASON 4.3.4 General Java NetLogo 4.3.5 General Logo-variant...through the use of relatively simple Python scripts. It also has built-in functions for parameter sweeps, and can plot the resulting fitness landscape ac...Nonetheless its ease of use, and support for automatic drawing of agents in 2D or 3D2 makes this a suitable platform for beginner programmers. 2Only in the

f (R ,Rμν 2) at one loop

NASA Astrophysics Data System (ADS)

Ohta, N.; Percacci, R.; Pereira, A. D.

2018-05-01

We compute the one-loop divergences in a theory of gravity with a Lagrangian of the general form f (R ,Rμ νRμ ν), on an Einstein background. We also establish that the one-loop effective action is invariant under a duality that consists of changing certain parameters in the relation between the metric and the quantum fluctuation field. Finally, we discuss the unimodular version of such a theory and establish its equivalence at one-loop order with the general case.

Conventionalism and integrable Weyl geometry

NASA Astrophysics Data System (ADS)

Pucheu, M. L.

2015-03-01

Since the appearance of Einstein's general relativity, gravitation has been associated to the space-time curvature. This theory introduced a geometrodynamic language which became a convenient tool to predict matter behaviour. However, the properties of space-time itself cannot be measurable by experiments. Taking Poincaré idea that the geometry of space-time is merely a convention, we show that the general theory of relativity can be completely reformulated in a more general setting, a generalization of Riemannian geometry, namely, the Weyl integrable geometry. The choice of this new mathematical language implies, among other things, that the path of particles and light rays should now correspond to Weylian geodesies. Such modification in the dynamic of bodies brings a new perception of physical phenomena that we will explore.

Einstein and the "Crucial" Experiment

ERIC Educational Resources Information Center

Holton, Gerald

1969-01-01

Examines the widespread view that it was the crucial Michelson-Morley experiment that led Einstein to formulate the special relativity theory. From Einstein's writings, evidence is presented that no such direct genetic connection exists. The author suggests that the historian of science must resist the experimenticist's fallacy of imposing a…

Lichnerowicz-type equations with sign-changing nonlinearities on complete manifolds with boundary

NASA Astrophysics Data System (ADS)

Albanese, Guglielmo; Rigoli, Marco

2017-12-01

We prove an existence theorem for positive solutions to Lichnerowicz-type equations on complete manifolds with boundary (M , ∂ M , 〈 , 〉) and nonlinear Neumann conditions. This kind of nonlinear problems arise quite naturally in the study of solutions for the Einstein-scalar field equations of General Relativity in the framework of the so called Conformal Method.

Static and Dynamic Traversable Wormholes

NASA Astrophysics Data System (ADS)

Adamiak, Jaroslaw P.

2008-09-01

The aim of this work is to discuss the effects found in static and dynamic wormholes that occur as a solution of Einstein equations in general relativity. The ground is prepared by presentation of faster than light effects, then the focus is narrowed to Morris-Thorne framework for a static spherically symmetric wormhole. Two types of dynamic worm-holes, evolving and rotating, are considered.

Rectification of General Relativity, Experimental Verifications, and Errors of the Wheeler School

NASA Astrophysics Data System (ADS)

Lo, C. Y.

2013-09-01

General relativity is not yet consistent. Pauli has misinterpreted Einstein's 1916 equivalence principle that can derive a valid field equation. The Wheeler School has distorted Einstein's 1916 principle to be his 1911 assumption of equivalence, and created new errors. Moreover, errors on dynamic solutions have allowed the implicit assumption of a unique coupling sign that violates the principle of causality. This leads to the space-time singularity theorems of Hawking and Penrose who "refute" applications for microscopic phenomena, and obstruct efforts to obtain a valid equation for the dynamic case. These errors also explain the mistakes in the press release of the 1993 Nobel Committee, who was unaware of the non-existence of dynamic solutions. To illustrate the damages to education, the MIT Open Course Phys. 8.033 is chosen. Rectification of errors confirms that E = mc2 is only conditionally valid, and leads to the discovery of the charge-mass interaction that is experimentally confirmed and subsequently the unification of gravitation and electromagnetism. The charge-mass interaction together with the unification predicts the weight reduction (instead of increment) of charged capacitors and heated metals, and helps to explain NASA's Pioneer anomaly and potentially other anomalies as well.

Cosmological applications of singular hypersurfaces in general relativity

NASA Astrophysics Data System (ADS)

Laguna-Castillo, Pablo

Three applications to cosmology of surface layers, based on Israel's formalism of singular hypersurfaces and thin shells in general relativity, are presented. Einstein's field equations are analyzed in the presence of a bubble nucleated in vacuum phase transitions within the context of the old inflationary universe scenario. The evolution of a bubble with vanishing surface energy density is studied. It is found that such bubbles lead to a worm-hole matching. Next, the observable four-dimensional universe is considered as a singular hypersurface of discontinuity embedded in a five-dimensional Kaluza-Klein cosmology. It is possible to rewrite the projected five-dimensional Einstein equations on the surface layer in a similar way to the four-dimensional Robertson-Walker cosmology equations. Next, a model is described for an infinite-length, straight U(1) cosmic string as a cylindrical, singular shell enclosing a region of false vacuum. A set of equations is introduced which are required to develop a three-dimensional computer code whose purpose is to study the process of intercommuting cosmic strings with the inclusion of gravitational effects. The outcome is evolution and constraint equations for the gravitational, scalar and gauge field of two initially separated, perpendicular, cosmic strings.

On the existence of topological dyons and dyonic black holes in anti-de Sitter Einstein-Yang-Mills theories with compact semisimple gauge groups

NASA Astrophysics Data System (ADS)

Baxter, J. Erik

2018-05-01

Here we study the global existence of "hairy" dyonic black hole and dyon solutions to four-dimensional, anti-de Sitter Einstein-Yang-Mills theories for a general simply connected and semisimple gauge group G, for the so-called topologically symmetric systems, concentrating here on the regular case. We generalise here cases in the literature which considered purely magnetic spherically symmetric solutions for a general gauge group and topological dyonic solutions for s u (N ) . We are able to establish the global existence of non-trivial solutions to all such systems, both near existing embedded solutions and as |Λ| → ∞. In particular, we can identify non-trivial solutions where the gauge field functions have no zeroes, which in the s u (N ) case proved important to stability. We believe that these are the most general analytically proven solutions in 4D anti-de Sitter Einstein-Yang-Mills systems to date.

Predicting Binary Black Hole Collisions Using Numerical Methods in Collaboration with LIGO

NASA Astrophysics Data System (ADS)

Afshari, Nousha; Lovelace, Geoffrey

2015-04-01

Detecting astronomical gravitational waves will soon open a new window on the universe. The effects of gravitational waves have already been seen indirectly, but a direct observation of these waves will test Einstein's theory of general relativity under the most extreme conditions. The Laser Interferometer Gravitational-Wave Observatory, or LIGO, will soon begin searching for gravitational waves, and the first direct detections are likely in the next few years. To help LIGO detect as many gravitational waves as possible, a major research effort is underway to accurately predict the expected waves. In this presentation, I will discuss new supercomputer simulations of merging black holes--some of the brightest sources of gravitational waves--that I have completed using the Spectral Einstein Code (http://www.black-holes.org/SpEC.html).

Theory and experiment in gravitational physics

NASA Technical Reports Server (NTRS)

Will, C. M.

1981-01-01

New technological advances have made it feasible to conduct measurements with precision levels which are suitable for experimental tests of the theory of general relativity. This book has been designed to fill a new need for a complete treatment of techniques for analyzing gravitation theory and experience. The Einstein equivalence principle and the foundations of gravitation theory are considered, taking into account the Dicke framework, basic criteria for the viability of a gravitation theory, experimental tests of the Einstein equivalence principle, Schiff's conjecture, and a model theory devised by Lightman and Lee (1973). Gravitation as a geometric phenomenon is considered along with the parametrized post-Newtonian formalism, the classical tests, tests of the strong equivalence principle, gravitational radiation as a tool for testing relativistic gravity, the binary pulsar, and cosmological tests.

Theory and experiment in gravitational physics

NASA Astrophysics Data System (ADS)

Will, C. M.

New technological advances have made it feasible to conduct measurements with precision levels which are suitable for experimental tests of the theory of general relativity. This book has been designed to fill a new need for a complete treatment of techniques for analyzing gravitation theory and experience. The Einstein equivalence principle and the foundations of gravitation theory are considered, taking into account the Dicke framework, basic criteria for the viability of a gravitation theory, experimental tests of the Einstein equivalence principle, Schiff's conjecture, and a model theory devised by Lightman and Lee (1973). Gravitation as a geometric phenomenon is considered along with the parametrized post-Newtonian formalism, the classical tests, tests of the strong equivalence principle, gravitational radiation as a tool for testing relativistic gravity, the binary pulsar, and cosmological tests.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiménez, Jose Beltrán; Heisenberg, Lavinia; Olmo, Gonzalo J., E-mail: jose.beltran@uclouvain.be, E-mail: Lavinia.Heisenberg@unige.ch, E-mail: gonzalo.olmo@csic.es

We generalize the ultraviolet sector of gravitation via a Born-Infeld action using lessons from massive gravity. The theory contains all of the elementary symmetric polynomials and is treated in the Palatini formalism. We show how the connection can be solved algebraically to be the Levi-Civita connection of an effective metric. The non-linearity of the algebraic equations yields several branches, one of which always reduces to General Relativity at low curvatures. We explore in detail a minimal version of the theory, for which we study solutions in the presence of a perfect fluid with special attention to the cosmological evolution. Inmore » vacuum we recover Ricci-flat solutions, but also an additional physical solution corresponding to an Einstein space. The existence of two physical branches remains for non-vacuum solutions and, in addition, the branch that connects to the Einstein space in vacuum is not very sensitive to the specific value of the energy density. For the branch that connects to the General Relativity limit we generically find three behaviours for the Hubble function depending on the equation of state of the fluid, namely: either there is a maximum value for the energy density that connects continuously with vacuum, or the energy density can be arbitrarily large but the Hubble function saturates and remains constant at high energy densities, or the energy density is unbounded and the Hubble function grows faster than in General Relativity. The second case is particularly interesting because it could offer an interesting inflationary epoch even in the presence of a dust component. Finally, we discuss the possibility of avoiding certain types of singularities within the minimal model.« less

Implications of Einstein-Weyl Causality on Quantum Mechanics

NASA Astrophysics Data System (ADS)

Bendaniel, David

A fundamental physical principle that has consequences for the topology of space-time is the principle of Einstein-Weyl causality. This also has quantum mechanical manifestations. Borchers and Sen have rigorously investigated the mathematical implications of Einstein-Weyl causality and shown the denumerable space-time Q2 would be implied. They were left with important philosophical paradoxes regarding the nature of the physical real line E, e.g., whether E = R, the real line of mathematics. In order to remove these paradoxes an investigation into a constructible foundation is suggested. We have pursued such a program and find it indeed provides a dense, denumerable space-time and, moreover, an interesting connection with quantum mechanics. We first show that this constructible theory contains polynomial functions which are locally homeomorphic with a dense, denumerable metric space R* and are inherently quantized. Eigenfunctions governing fields can then be effectively obtained by computational iteration. Postulating a Lagrangian for fields in a compactified space-time, we get a general description of which the Schrodinger equation is a special case. From these results we can then also show that this denumerable space-time is relational (in the sense that space is not infinitesimally small if and only if it contains a quantized field) and, since Q2 is imbedded in R*2, it directly fulfills the strict topological requirements for Einstein-Weyl causality. Therefore, the theory predicts that E = R*.

Einstein, the Universe, and All That: An Introduction to Relativity

NASA Technical Reports Server (NTRS)

Prescod-Weinstein, Chandra

2011-01-01

Black holes) an expanding universe) space and time inextricably tied together) GPS ... What was this Einstein guy thinking?!? In this tutorial) I'll give an overview of Einstein's theories of relativity and the wild things they say about our Universe. What really happens when a particle crosses an event horizon? What is the future of the Universe? And how can we know it? Wh I'll try to touch on these questions and in so doing) give the talks in the Cosmology) Gravitation and Relativity sessions some context.

An Out-of-Math Experience: Einstein, Relativity, and the Developmental Mathematics Student.

ERIC Educational Resources Information Center

Fiore, Greg

2000-01-01

Discusses Einstein's special relativity theory and some of the developmental mathematics involved. Presents motivational classroom materials used in discussing relative-motion problems, evaluating a radical expression, graphing with asymptotes, interpreting a graph, studying variation, and solving literal and radical equations. (KHR)

Hidden symmetries on Kerr-NUT-(A)dS metrics of Einstein-Sasaki type

NASA Astrophysics Data System (ADS)

Visinescu, Mihai

2013-01-01

The hidden symmetries of higher dimensional Euclideanised Kerr-NUT-(A)dS metrics are investigated. In certain scaling limits these metrics are related to the Einstein-Sasaki ones. The complete set of Killing-Yano tensors of the Einstein-Sasaki spaces are presented. For this purpose the Killing forms of the Calabi-Yau cone over the Einstein-Sasaki manifold are constructed. Two new Killing forms on Einstein-Sasaki manifolds are identified associated with the complex volume form of the cone manifolds. As a concrete example we present the complete set of Killing-Yano tensors on the five-dimensional Einstein-Sasaki Y(p, q) spaces. The corresponding hidden symmetries are not anomalous and the geodesic equations are superintegrable.

Locality, reflection, and wave-particle duality

NASA Astrophysics Data System (ADS)

Mugur-Schächter, Mioara

1987-08-01

Bell's theorem is believed to establish that the quantum mechanical predictions do not generally admit a causal representation compatible with Einsten's principle of separability, thereby proving incompatibility between quantum mechanics and relativity. This interpretation is contested via two convergent approaches which lead to a sharp distinction between quantum nonseparability and violation of Einstein's theory of relativity. In a first approach we explicate from the quantum mechanical formalism a concept of “reflected dependence.” Founded on this concept, we produce a causal representation of the quantum mechanical probability measure involved in Bell's proof, which is clearly separable in Einstein's sense, i.e., it does not involve supraluminal velocities, and nevertheless is “nonlocal” in Bell's sense. So Bell locality and Einstein separability are distinct qualifications, and Bell nonlocality (or Bell nonseparability) and Einstein separability are not incompatible. It is then proved explicitly that with respect to the mentioned representation Bell's derivation does not hold. So Bell's derivation does not establish that any Einstein-separable representation is incompatible with quantum mechanics. This first—negative—conclusion is a syntactic fact. The characteristics of the representation and of the reasoning involved in the mentioned counterexample to the usual interpretation of Bell's theorem suggest that the representation used—notwithstanding its ability to bring forth the specified syntactic fact—is not factually true. Factual truth and syntactic properties also have to be radically distinguished in their turn. So, in a second approach, starting from de Broglie's initial relativistic model of a microsystem, a deeper, factually acceptable representation is constructed. The analyses leading to this second representation show that quantum mechanics does indeed involve basically a certain sort of nonseparability, called here de Broglie-Bohr quantum nonseparability. But the de Broglie-Bohr quantum nonseparability is shown to stem directly from the relativistic character of the considerations which led Louis de Broglie to the fundamental relation p = h/λ, thereby being essentially consistent with relativity. As to Einstein separability, it appears to be a still insufficiently specified concept of which a future, improved specification, will probably be explicitly harmonizable with the de Broglie-Bohr quantum nonseparability. The ensemble of the conclusions obtained here brings forth a new concept of causality, a concept of folded, zigzag, reflexive causality, with respect to which the type of causality conceived of up to now appears as a particular case of outstretched, one-way causality. The reflexive causality is found compatible with the results of Aspect's experiment, and it suggests new experiments. Considered globally, the conclusions obtained in the present work might convert the conceptual situation created by Bell's proof into a process of unification of quantum mechanics and relativity.

Einstein and Millikan

NASA Astrophysics Data System (ADS)

Erwin, Charlotte

2005-03-01

Albert Einstein traveled to America by boat during the great depression to consult with scientists at the California Institute of Technology. He was a theoretical physicist, a Nobel Prize winner, and a 20th century folk hero. Few members of the general public understood his theories, but they idolized him all the same. The invitation came from physicist Robert Millikan, who had initiated a visiting-scholars program at Caltech shortly after he became head of the school in 1921. Einstein's visits to the campus in 1931, 1932, and 1933 capped Millikan's campaign to make Caltech one of the physics capitals of the world. Mount Wilson astronomer Edwin Hubble's discovery that redshifts are proportional to their distances from the observer challenged Einstein's cosmological picture of a static universe. The big question at Caltech in 1931 was whether Einstein would give up his cosmological constant and accept the idea of an expanding universe. By day, Einstein discussed his theory and its interpretation at length with Richard Tolman, Hubble, and the other scientists on the campus. By night, Einstein filled his travel diary with his personal impressions. During his third visit, Einstein sidestepped as long as possible the question of whether conditions in Germany might prevent his return there. After the January 30 announcement that Hitler had become chancellor of Germany, the question could no longer be evaded. He postponed his return trip for a few weeks and then went to Belgium for several months instead of to Berlin. In the fall of 1933, Albert Einstein returned to the United States as an emigre and became a charter member of Abraham Flexner's new Institute for Advanced Study in Princeton, New Jersey. Why did Einstein go to Princeton and not Pasadena?

Equivalence principles and electromagnetism

NASA Technical Reports Server (NTRS)

Ni, W.-T.

1977-01-01

The implications of the weak equivalence principles are investigated in detail for electromagnetic systems in a general framework. In particular, it is shown that the universality of free-fall trajectories (Galileo weak equivalence principle) does not imply the validity of the Einstein equivalence principle. However, the Galileo principle plus the universality of free-fall rotation states does imply the Einstein principle.

Perturbation of a planetary orbit by the Lambda-term (dark energy) in Einstein equations

NASA Astrophysics Data System (ADS)

Dumin, Yurii

The problem of cosmological influences at small (e.g. interplanetary) scales is discussed for a few decades, starting from the early 1930's, but still remains unsolved definitively by now [1]. This subject became especially topical in the context of the dark-energy-dominated cosmology, because the commonly-used arguments against the local Hubble expansion (such as Einstein-Straus theorem [2]) are inapplicable when the most contribution to the energy density of the Universe comes from the perfectly-uniform dark energy (Lambda-term). Moreover, there are some empirical evidences in favor of the local cosmological influences. For example, inclusion of the local Hubble expansion into dynamics of the Earth-Moon system enables us to resolve a long-standing discrepancy in the rates of secular increase of the lunar semi-major axis (a) mea-sured by the lunar laser ranging and (b) derived from the astrometric observations of the Earth's rotation deceleration [3, 4]. The aim of the present report is to provide a detailed mathematical treatment of the respective two-body problem in the framework of General Relativity, which is based on the Kottler metric reduced to the Robertson-Walker cosmological asymptotics, as outlined in our earlier work [5]. References: 1. W.B. Bonnor. Gen. Rel. Grav., v.32, p.1005 (2000). 2. A. Einstein and E.G. Straus. Rev. Mod. Phys., v.17, p.120 (1945). 3. Yu.V. Dumin. Adv. Space Res., v.31, p.2461 (2003). 4. Yu.V. Dumin. In Proc. 11th Marcel Grossmann Meeting on General Relativity, World Sci., Singapore, p.1752 (2008). 5. Yu.V. Dumin. Phys. Rev. Lett., v.98, p.059001 (2007).

Complete integrability of geodesics in toric Sasaki-Einstein spaces

NASA Astrophysics Data System (ADS)

Visinescu, Mihai

2016-01-01

We describe a method for constructing Killing-Yano tensors on toric Sasaki- Einstein manifolds using their geometrical properties. We take advantage of the fact that the metric cones of these spaces are Calabi-Yau manifolds. The complete list of special Killing forms can be extracted making use of the description of the Calabi-Yau manifolds in terms of toric data. This general procedure for toric Sasaki-Einstein manifolds is exemplified in the case of the 5-dimensional spaces Yp,q and T1,1. Finally we discuss the integrability of geodesic motion in these spaces.

General Relativity and Spacetime Relationism.

NASA Astrophysics Data System (ADS)

Hoefer, Carl

1992-01-01

This dissertation takes up the project of showing that, in the context of the general theory of relativity (GTR), spacetime relationism is not a refuted or hopeless view, as many in the recent literature have maintained (John Earman, Michael Friedman, and others). Most of the challenges to the relationist view in General Relativity can be satisfactorily answered; in addition, the opposing absolutist and substantivalist views of spacetime can be shown to be problematic. The crucial burden for relationists concerned with GTR is to show that the realistic cosmological models, i.e. those that may be roughly accurate representations of our universe, satisfy Mach's ideas about the origin of inertia. This dissertation clears the way for and begins such a demonstration. After a brief discussion of the problem of the nature of spacetime and its history in the Introduction, chapters 2 and 3 provide conceptual analysis and criticism of contemporary philosophical arguments about relationism, absolutism, and particularly substantivalism. The current best arguments in favor of substantivalism are shown to be flawed, with the exception of the argument from inertial and metrical structure; and on this issue, it is shown that both relationism and substantivalism need to argue for modifications of GTR (restriction of its models to those with certain features) in order to have a non-trivial explanation of inertial and metrical structure. For relationists, a Machian account of the origin of inertia in some models of GTR is required. Chapter 4 demonstrates that such a Machian account is equivalent to the demand for a truly general relativity of motion. Chapter 5 explores the history of Einstein's commitment to Mach's ideas in his work on GTR. Through an examination of the history of Einstein's attempts to impose Machian constraints on the models of General Relativity, further insight into the nature of this problem is obtained, as are reasons to believe that the project is by no means hopeless.

The Stokes-Einstein relation at moderate Schmidt number.

PubMed

Balboa Usabiaga, Florencio; Xie, Xiaoyi; Delgado-Buscalioni, Rafael; Donev, Aleksandar

2013-12-07

The Stokes-Einstein relation for the self-diffusion coefficient of a spherical particle suspended in an incompressible fluid is an asymptotic result in the limit of large Schmidt number, that is, when momentum diffuses much faster than the particle. When the Schmidt number is moderate, which happens in most particle methods for hydrodynamics, deviations from the Stokes-Einstein prediction are expected. We study these corrections computationally using a recently developed minimally resolved method for coupling particles to an incompressible fluctuating fluid in both two and three dimensions. We find that for moderate Schmidt numbers the diffusion coefficient is reduced relative to the Stokes-Einstein prediction by an amount inversely proportional to the Schmidt number in both two and three dimensions. We find, however, that the Einstein formula is obeyed at all Schmidt numbers, consistent with linear response theory. The mismatch arises because thermal fluctuations affect the drag coefficient for a particle due to the nonlinear nature of the fluid-particle coupling. The numerical data are in good agreement with an approximate self-consistent theory, which can be used to estimate finite-Schmidt number corrections in a variety of methods. Our results indicate that the corrections to the Stokes-Einstein formula come primarily from the fact that the particle itself diffuses together with the momentum. Our study separates effects coming from corrections to no-slip hydrodynamics from those of finite separation of time scales, allowing for a better understanding of widely observed deviations from the Stokes-Einstein prediction in particle methods such as molecular dynamics.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krtous, Pavel; Frolov, Valeri P.; Kubiznak, David

We prove that the most general solution of the Einstein equations with the cosmological constant which admits a principal conformal Killing-Yano tensor is the Kerr-NUT-(A)dS metric. Even when the Einstein equations are not imposed, any spacetime admitting such hidden symmetry can be written in a canonical form which guarantees the following properties: it is of the Petrov type D, it allows the separation of variables for the Hamilton-Jacobi, Klein-Gordon, and Dirac equations, the geodesic motion in such a spacetime is completely integrable. These results naturally generalize the results obtained earlier in four dimensions.

Growth histories in bimetric massive gravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berg, Marcus; Buchberger, Igor; Enander, Jonas

2012-12-01

We perform cosmological perturbation theory in Hassan-Rosen bimetric gravity for general homogeneous and isotropic backgrounds. In the de Sitter approximation, we obtain decoupled sets of massless and massive scalar gravitational fluctuations. Matter perturbations then evolve like in Einstein gravity. We perturb the future de Sitter regime by the ratio of matter to dark energy, producing quasi-de Sitter space. In this more general setting the massive and massless fluctuations mix. We argue that in the quasi-de Sitter regime, the growth of structure in bimetric gravity differs from that of Einstein gravity.

Competition between Bose-Einstein Condensation and Spin Dynamics.

PubMed

Naylor, B; Brewczyk, M; Gajda, M; Gorceix, O; Maréchal, E; Vernac, L; Laburthe-Tolra, B

2016-10-28

We study the impact of spin-exchange collisions on the dynamics of Bose-Einstein condensation by rapidly cooling a chromium multicomponent Bose gas. Despite relatively strong spin-dependent interactions, the critical temperature for Bose-Einstein condensation is reached before the spin degrees of freedom fully thermalize. The increase in density due to Bose-Einstein condensation then triggers spin dynamics, hampering the formation of condensates in spin-excited states. Small metastable spinor condensates are, nevertheless, produced, and they manifest in strong spin fluctuations.

Scalar-tensor Theories of Gravity: Some personal history

NASA Astrophysics Data System (ADS)

Brans, Carl H.

2008-12-01

From a perspective of some 50 years or more, this paper reviews my recall of the early days of scalar-tensor alternatives to standard Einstein general relativistic theory of gravity. Of course, the story begins long before my involvement, going back to the proposals of Nordström in 1914, and that of Kaluza, Klein, et al., a few years later, sol include reviews of these seminal ideas and those that followed in the 1920's through the 1940's. This early work concerned the search for a Unified Field Theory, unifying gravity and Electromagnetism, using five dimensional manifolds. This formalism included not only the electromagnetic spacetime vector potential within the five-metric, but also a spacetime scalar as the five-five metric component. Although this was at first regarded more as a nuisance, to be set to a constant, it turned out later that Fierz, Jordan, Einstein and Bergmann noticed that this scalar could be a field, possibly related to the Newtonian gravitational constant. Relatively little theoretical and experimental attention was given to these ideas until after the second world war when Bob Dicke, motivated by the ideas of Mach, Dirac, and others, suggested that this additional scalar, coupled only to the metric and matter, could provide a reasonable and viable alternative to standard Einstein theory. This is the point of my direct involvement with these topics. However, it was Dicke's prominence and expertise in experimental work, together with the blossoming of NASA's experimental tools, that caused the explosion of interest, experimental and theoretical, in this possible alternative to standard Einstein theory. This interest has waxed and waned over the last 50 years, and we summarize some of this work.

[THE ROLE OF PHILOSOPHICAL REFLECTIONS OF STANISLAW ZAREMBA IN THE CONTEXT OF A DISPUTE ON THE FOUNDATIONS OF THE THEORY OF RELATIVITY].

PubMed

Polak, Paweł

2014-01-01

The aim of this paper is to present the philosophical background of Stanisław Zaremba's critique of Einstein's theory of relativity. In the 1920s, Zaremba was the most prominent Polish opponent of this theory. His papers influenced some discussions related to Einstein's theory, especially in France and in Poland. This paper takes also into account the development of Zaremba's critique. The analysis of his papers shows that he never became a follower of the Einstein's theory of relativity. Such a statement compels us to confront it with the previous interpretations of Zaremba's thought.

The general theory of relativity - Why 'It is probably the most beautiful of all existing theories'

NASA Astrophysics Data System (ADS)

Chandrasekhar, S.

1984-03-01

An attempt is made to objectively evaluate the frequent judgment of Einstein's general theory of relativity, by such distinguished physicists as Pauli (1921), Dirac, Born, and Rutherford, as 'beautiful' and 'a work of art'. The criteria applied are that of Francis Bacon ('There is no excellent beauty that hath not some strangeness in the proportions') and that of Heisenberg ('Beauty is the proper conformity of the parts to one another and to the whole'). The strangeness in the proportions of the theory of general relativity consists in its relating, through juxtaposition, the concepts of space and time and those of matter and motion; these had previously been considered entirely independent. The criterion of 'conformity' is illustrated through the directness with which the theory allows the description of black holes.

What is Gravitational Lensing? (LBNL Summer Lecture Series)

ScienceCinema

Leauthaud, Alexie [Univ. of California, Berkeley, CA (United States). Berkeley Center for Cosmological Physics (BCCP); Nakajima, Reiko [Univ. of California, Berkeley, CA (United States). Berkeley Center for Cosmological Physics (BCCP)

2018-05-04

Summer Lecture Series 2009: Gravitational lensing is explained by Einstein's general theory of relativity: galaxies and clusters of galaxies, which are very massive objects, act on spacetime by causing it to become curved. Alexie Leauthaud and Reiko Nakajima, astrophysicists with the Berkeley Center for Cosmological Physics, will discuss how scientists use gravitational lensing to investigate the nature of dark energy and dark matter in the universe.

What is Gravitational Lensing? (LBNL Summer Lecture Series)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leauthaud, Alexie; Nakajima, Reiko

2009-07-28

Summer Lecture Series 2009: Gravitational lensing is explained by Einstein's general theory of relativity: galaxies and clusters of galaxies, which are very massive objects, act on spacetime by causing it to become curved. Alexie Leauthaud and Reiko Nakajima, astrophysicists with the Berkeley Center for Cosmological Physics, will discuss how scientists use gravitational lensing to investigate the nature of dark energy and dark matter in the universe.

Experimental constraints on metric and non-metric theories of gravity

NASA Technical Reports Server (NTRS)

Will, Clifford M.

1989-01-01

Experimental constraints on metric and non-metric theories of gravitation are reviewed. Tests of the Einstein Equivalence Principle indicate that only metric theories of gravity are likely to be viable. Solar system experiments constrain the parameters of the weak field, post-Newtonian limit to be close to the values predicted by general relativity. Future space experiments will provide further constraints on post-Newtonian gravity.

Gravitational Lensing

ScienceCinema

Lincoln, Don

2018-01-16

In a long line of intellectual triumphs, Einstein’s theory of general relativity was his greatest and most imaginative. It tells us that what we experience as gravity can be most accurately described as the bending of space itself. This idea leads to consequences, including gravitational lensing, which is caused by light traveling in this curved space. This is works in a way analogous to a lens (and hence the name). In this video, Fermilab’s Dr. Don Lincoln explains a little general relativity, a little gravitational lensing, and tells us how this phenomenon allows us to map out the matter of the entire universe, including the otherwise-invisible dark matter.

A superconducting gyroscope to test Einstein's general theory of relativity

NASA Technical Reports Server (NTRS)

Everitt, C. W. F.

1978-01-01

Schiff (1960) proposed a new test of general relativity based on measuring the precessions of the spin axes of gyroscopes in earth orbit. Since 1963 a Stanford research team has been developing an experiment to measure the two effects calculated by Schiff. The gyroscope consists of a uniform sphere of fused quartz 38 mm in diameter, coated with superconductor, electrically suspended and spinning at about 170 Hz in vacuum. The paper describes the proposed flight apparatus and the current state of development of the gyroscope, including techniques for manufacturing and measuring the gyro rotor and housing, generating ultralow magnetic fields, and mechanizing the readout.

Amazonia Introduced to General Relativity: The May 29, 1919, Solar Eclipse from a North-Brazilian Point of View

NASA Astrophysics Data System (ADS)

Crispino, Luís C. B.; de Lima, Marcelo C.

2016-12-01

In 1919, A. C. D. Crommelin and C. R. Davidson, British astronomers from the Greenwich Observatory in England, passed by Amazonia on their Brazilian journey aiming to measure the bending of stars' light rays during the total solar eclipse of May 29, 1919, and thereby put the theory of general relativity to the test. In the context of Crommelin's and Davidson's visit, we discuss how Amazonia was introduced to Einstein's theory of gravitation, and also the observations and repercussions of the May 29, 1919, solar eclipse in Belém, capital city of the North-Brazilian Pará state.

Three-variable solution in the (2+1)-dimensional null-surface formulation

NASA Astrophysics Data System (ADS)

Harriott, Tina A.; Williams, J. G.

2018-04-01

The null-surface formulation of general relativity (NSF) describes gravity by using families of null surfaces instead of a spacetime metric. Despite the fact that the NSF is (to within a conformal factor) equivalent to general relativity, the equations of the NSF are exceptionally difficult to solve, even in 2+1 dimensions. The present paper gives the first exact (2+1)-dimensional solution that depends nontrivially upon all three of the NSF's intrinsic spacetime variables. The metric derived from this solution is shown to represent a spacetime whose source is a massless scalar field that satisfies the general relativistic wave equation and the Einstein equations with minimal coupling. The spacetime is identified as one of a family of (2+1)-dimensional general relativistic spacetimes discovered by Cavaglià.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gergely, Laszlo A.

We study the possibility of brane-world generalization of the Einstein-Straus Swiss-cheese cosmological model. We find that the modifications induced by the brane-world scenario are excessively restrictive. At a first glance only the motion of the boundary is modified and the fluid in the exterior region is allowed to have pressure. The general relativistic Einstein-Straus model emerges in the low density limit. However by imposing that the central mass in the Schwarzschild voids is constant, a combination of the junction conditions and modified cosmological evolution leads to the conclusion that the brane is flat. Thus no generic Swiss-cheese universe can existmore » on the brane. The conclusion is not altered by the introduction of a cosmological constant in the FLRW regions. This shows that although allowed in the low density limit, the Einstein-Straus universe cannot emerge from cosmological evolution in the brane-world scenario.« less

Extrema of mass, first law of black hole mechanics, and a staticity theorem in Einstein-Maxwell-axion-dilaton gravity

NASA Astrophysics Data System (ADS)

Rogatko, Marek

1998-08-01

Using the ADM formulation of the Einstein-Maxwell axion-dilaton gravity we derive the formulas for the variation of mass and other asymptotic conserved quantities in the theory under consideration. Generalizing this kind of reasoning to the initial data for the manifold with an interior boundary we get the generalized first law of black hole mechanics. We consider an asymptotically flat solution to the Einstein-Maxwell axion-dilaton gravity describing a black hole with a Killing vector field timelike at infinity, the horizon of which comprises a bifurcate Killing horizon with a bifurcate surface. Supposing that the Killing vector field is asymptotically orthogonal to the static hypersurface with boundary S and a compact interior, we find that the solution is static in the exterior world, when the timelike vector field is normal to the horizon and has vanishing electric and axion-electric fields on static slices.

Determination of diffusion coefficient in disordered organic semiconductors

NASA Astrophysics Data System (ADS)

Rani, Varsha; Sharma, Akanksha; Ghosh, Subhasis

2016-05-01

Charge carrier transport in organic semiconductors is dominated by positional and energetic disorder in Gaussian density of states (GDOS) and is characterized by hopping through localized states. Due to the immobilization of charge carriers in these localized states, significant non-uniform carrier distribution exists, resulting diffusive transport. A simple, nevertheless powerful technique to determine diffusion coefficient D in disordered organic semiconductors has been presented. Diffusion coefficients of charge carriers in two technologically important organic molecular semiconductors, Pentacene and copper phthalocyanine (CuPc) have been measured from current-voltage (J-V) characteristics of Al/Pentacene/Au and Al/CuPc/Au based Schottky diodes. Ideality factor g and carrier mobility μ have been calculated from the exponential and space charge limited region respectively of J-V characteristics. Classical Einstein relation is not valid in organic semiconductors due to energetic disorders in DOS. Using generalized Einstein relation, diffusion coefficients have been obtained to be 1.31×10-6 and 1.73×10-7 cm2/s for Pentacene and CuPc respectively.

Inflation in Einstein-Cartan theory with energy-momentum tensor with spin

NASA Technical Reports Server (NTRS)

Fennelly, A. J.; Bradas, James C.; Smalley, Larry L.

1988-01-01

Generalized, or power-law, inflation is shown to necessarily exist for a simple, anisotropic (Bianchi Type I) cosmology in the Einstein-Cartan gravitational theory with the Ray-Smalley (RS) improved energy-momentum tensor with spin. Formal solution of the EC field equations with the fluid equations of motion explicitly shows inflation caused by the RS spin angular kinetic energy density.

A numerical approach to finding general stationary vacuum black holes

NASA Astrophysics Data System (ADS)

Adam, Alexander; Kitchen, Sam; Wiseman, Toby

2012-08-01

The Harmonic Einstein equation is the vacuum Einstein equation supplemented by a gauge fixing term which we take to be that of DeTurck. For static black holes analytically continued to Riemannian manifolds without boundary at the horizon, this equation has previously been shown to be elliptic, and Ricci flow and Newton’s method provide good numerical algorithms to solve it. Here we extend these techniques to the arbitrary cohomogeneity stationary case which must be treated in Lorentzian signature. For stationary spacetimes with globally timelike Killing vector the Harmonic Einstein equation is elliptic. In the presence of horizons and ergo-regions it is less obviously so. Motivated by the Rigidity theorem we study a class of stationary black hole spacetimes which is general enough to include many interesting higher dimensional solutions. We argue the Harmonic Einstein equation consistently truncates to this class of spacetimes giving an elliptic problem. The Killing horizons and axes of rotational symmetry are boundaries for this problem and we determine boundary conditions there. As a simple example we numerically construct 4D rotating black holes in a cavity using Anderson’s boundary conditions. We demonstrate both Newton’s method and Ricci flow to find these Lorentzian solutions.

The Viking Relativity Experiment

NASA Technical Reports Server (NTRS)

Shapiro, I. I.; Reasenberg, R. D.; Macneil, P. E.; Goldstein, R. B.; Brenkle, J. P.; Cain, D. L.; Komarek, T.; Zygielbaum, A. I.; Cuddihy, W. F.; Michael, W. H., Jr.

1977-01-01

Measurements of the round-trip time of flight of radio signals transmitted from the earth to the Viking spacecraft are being analyzed to test the predictions of Einstein's theory of general relativity. According to this theory the signals will be delayed by up to approximately 250 microsec owing to the direct effect of solar gravity on the propagation. A very preliminary qualitative analysis of the Viking data obtained near the 1976 superior conjunction of Mars indicates agreement with the predictions to within the estimated uncertainty of 0.5%.

How black holes saved relativity

NASA Astrophysics Data System (ADS)

Prescod-Weinstein, Chanda

2016-02-01

While there have been many popular-science books on the historical and scientific legacy of Albert Einstein's general theory of relativity, a gap exists in the literature for a definitive, accessible history of the theory's most famous offshoot: black holes. In Black Hole, the science writer Marcia Bartusiak aims for a discursive middle ground, writing solely about black holes at a level suitable for both high-school students and more mature readers while also giving some broader scientific context for black-hole research.

Relativity experiment on Helios - A status report

NASA Technical Reports Server (NTRS)

Anderson, J. D.; Melbourne, W. G.; Cain, D. L.; Lau, E. K.; Wong, S. K.; Kundt, W.

1975-01-01

The relativity experiment on Helios (Experiment 11) uses S-band and Doppler data, and spacecraft-solar-orbital data to measure the effects of general relativity in the solar system and the quadrupole moment in the solar gravitational field. Specifically, Experiment 11 is converned with measuring the following effects: (1) relativistic orbital corrections described by two parameters of the space-time metric which are both equal to unity in Einstein's theory; (2) orbital perturbations caused by a finite quadrupole moment of an oblate sun, described by zonal harmonics in the solar gravitational field.

Testing Einstein in Space: The Gravity Probe B Relativity Mission

NASA Astrophysics Data System (ADS)

Mester, John

The Gravity Probe B Relativity Mission was successfully launched on April 20, 2004 from Vandenberg Air Force Base in California, a culmination of 40 years of collaborative development at Stanford University and NASA. The goal of the GP-B experiment is to perform precision tests of two independent predictions of general relativity, the geodetic effect and frame dragging. On-orbit cryogenic operations lasted 17.3 months, exceeding requirements. Analysis of the science data is now in progress with a planned announcement of results scheduled for December 2007.

The Gravity-Probe-B relativity gyroscope experiment - Development of the prototype flight instrument

NASA Technical Reports Server (NTRS)

Turneaure, J. P.; Everitt, C. W. F.; Parkinson, B. W.; Bardas, D.; Breakwell, J. V.

1989-01-01

The Gravity-Probe-B relativity gyroscope experiment (GP-B) will measure the geodetic and frame-dragging precession rates of gyroscopes in a 650 km high polar orbit about the earth. The goal is to measure these two effects, which are predicted by Einstein's General Theory of Relativity, to 0.01 percent (geodetic) and 1 percent (frame-dragging). This paper presents the development progress for full-size prototype flight hardware including the gyroscopes, gyro readout and magnetic shielding system, and an integrated ground test instrument.

Comparing numerical and analytic approximate gravitational waveforms

NASA Astrophysics Data System (ADS)

Afshari, Nousha; Lovelace, Geoffrey; SXS Collaboration

2016-03-01

A direct observation of gravitational waves will test Einstein's theory of general relativity under the most extreme conditions. The Laser Interferometer Gravitational-Wave Observatory, or LIGO, began searching for gravitational waves in September 2015 with three times the sensitivity of initial LIGO. To help Advanced LIGO detect as many gravitational waves as possible, a major research effort is underway to accurately predict the expected waves. In this poster, I will explore how the gravitational waveform produced by a long binary-black-hole inspiral, merger, and ringdown is affected by how fast the larger black hole spins. In particular, I will present results from simulations of merging black holes, completed using the Spectral Einstein Code (black-holes.org/SpEC.html), including some new, long simulations designed to mimic black hole-neutron star mergers. I will present comparisons of the numerical waveforms with analytic approximations.

Fragments of Science: Festschrift for Mendel Sachs

NASA Astrophysics Data System (ADS)

Ram, Michael

1999-11-01

The Table of Contents for the full book PDF is as follows: * Preface * Sketches at a Symposium * For Mendel Sachs * The Constancy of an Angular Point of View * Information-Theoretic Logic and Transformation-Theoretic Logic * The Invention of the Transistor and the Realization of the Hole * Mach's Principle, Newtonian Gravitation, Absolute Space, and Einstein * The Sun, Our Variable Star * The Inconstant Sun: Symbiosis of Time Variations of Sunspots, Atmospheric Radiocarbon, Aurorae, and Tree Ring Growth * Other Worlds * Super-Classical Quantum Mechanics * A Probabilistic Approach to the Phase Problem of X-Ray Crystallography * A Nonlinear Twist on Inertia Gives Unified Electroweak Gravitation * Neutrino Oscillations * On an Incompleteness in the General-Relativistic Description of Gravitation * All Truth is One * Ideas of Physics: Correspondence between Colleagues * The Influence of the Physics and Philosophy of Einstein's Relativity on My Attitudes in Science: An Autobiography

Gravitational waves — A review on the theoretical foundations of gravitational radiation

NASA Astrophysics Data System (ADS)

Dirkes, Alain

2018-05-01

In this paper, we review the theoretical foundations of gravitational waves in the framework of Albert Einstein’s theory of general relativity. Following Einstein’s early efforts, we first derive the linearized Einstein field equations and work out the corresponding gravitational wave equation. Moreover, we present the gravitational potentials in the far away wave zone field point approximation obtained from the relaxed Einstein field equations. We close this review by taking a closer look on the radiative losses of gravitating n-body systems and present some aspects of the current interferometric gravitational waves detectors. Each section has a separate appendix contribution where further computational details are displayed. To conclude, we summarize the main results and present a brief outlook in terms of current ongoing efforts to build a spaced-based gravitational wave observatory.

A Conceptual Derivation of Einstein's Postulates of Special Relativity.

ERIC Educational Resources Information Center

Bearden, Thomas E.

This document presents a discussion and conceptual derivation of Einstein's postulates of special relativity. The perceptron approach appears to be a fundamentally new manner of regarding physical phenomena and it is hoped that physicists will interest themselves in the concept. (Author)

Infrared lessons for ultraviolet gravity: the case of massive gravity and Born-Infeld

NASA Astrophysics Data System (ADS)

Beltrán Jiménez, Jose; Heisenberg, Lavinia; Olmo, Gonzalo J.

2014-11-01

We generalize the ultraviolet sector of gravitation via a Born-Infeld action using lessons from massive gravity. The theory contains all of the elementary symmetric polynomials and is treated in the Palatini formalism. We show how the connection can be solved algebraically to be the Levi-Civita connection of an effective metric. The non-linearity of the algebraic equations yields several branches, one of which always reduces to General Relativity at low curvatures. We explore in detail a minimal version of the theory, for which we study solutions in the presence of a perfect fluid with special attention to the cosmological evolution. In vacuum we recover Ricci-flat solutions, but also an additional physical solution corresponding to an Einstein space. The existence of two physical branches remains for non-vacuum solutions and, in addition, the branch that connects to the Einstein space in vacuum is not very sensitive to the specific value of the energy density. For the branch that connects to the General Relativity limit we generically find three behaviours for the Hubble function depending on the equation of state of the fluid, namely: either there is a maximum value for the energy density that connects continuously with vacuum, or the energy density can be arbitrarily large but the Hubble function saturates and remains constant at high energy densities, or the energy density is unbounded and the Hubble function grows faster than in General Relativity. The second case is particularly interesting because it could offer an interesting inflationary epoch even in the presence of a dust component. Finally, we discuss the possibility of avoiding certain types of singularities within the minimal model.

Quasi-topological Ricci polynomial gravities

NASA Astrophysics Data System (ADS)

Li, Yue-Zhou; Liu, Hai-Shan; Lü, H.

2018-02-01

Quasi-topological terms in gravity can be viewed as those that give no contribution to the equations of motion for a special subclass of metric ansätze. They therefore play no rôle in constructing these solutions, but can affect the general perturbations. We consider Einstein gravity extended with Ricci tensor polynomial invariants, which admits Einstein metrics with appropriate effective cosmological constants as its vacuum solutions. We construct three types of quasi-topological gravities. The first type is for the most general static metrics with spherical, toroidal or hyperbolic isometries. The second type is for the special static metrics where g tt g rr is constant. The third type is the linearized quasitopological gravities on the Einstein metrics. We construct and classify results that are either dependent on or independent of dimensions, up to the tenth order. We then consider a subset of these three types and obtain Lovelock-like quasi-topological gravities, that are independent of the dimensions. The linearized gravities on Einstein metrics on all dimensions are simply Einstein and hence ghost free. The theories become quasi-topological on static metrics in one specific dimension, but non-trivial in others. We also focus on the quasi-topological Ricci cubic invariant in four dimensions as a specific example to study its effect on holography, including shear viscosity, thermoelectric DC conductivities and butterfly velocity. In particular, we find that the holographic diffusivity bounds can be violated by the quasi-topological terms, which can induce an extra massive mode that yields a butterfly velocity unbound above.

Homogeneous, anisotropic three-manifolds of topologically massive gravity

NASA Astrophysics Data System (ADS)

Nutku, Y.; Baekler, P.

1989-10-01

We present a new class of exact solutions of Deser, Jackiw, and Templeton's theory (DJT) of topologically massive gravity which consists of homogeneous, anisotropic manifolds. In these solutions the coframe is given by the left-invariant 1-forms of 3-dimensional Lie algebras up to constant scale factors. These factors are fixed in terms of the DJT coupling constant μ which is the constant of proportionality between the Einstein and Cotton tensors in 3-dimensions. Differences between the scale factors result in anisotropy which is a common feature of topologically massive 3-manifolds. We have found that only Bianchi Types VI, VIII, and IX lead to nontrivial solutions. Among these, a Bianchi Type IX, squashed 3-sphere solution of the Euclideanized DJT theory has finite action. Bianchi Type VIII, IX solutions can variously be embedded in the de Sitter/anti-de Sitter space. That is, some DJT 3-manifolds that we shall present here can be regarded as the basic constituent of anti-de Sitter space which is the ground state solution in higher dimensional generalization of Einstein's general relativity.

Homogeneous, anisotropic three-manifolds of topologically massive gravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nutku, Y.; Baekler, P.

1989-10-01

We present a new class of exact solutions of Deser, Jackiw, and Templeton's theory (DJT) of topologically massive gravity which consists of homogeneous, anisotropic manifolds. In these solutions the coframe is given by the left-invariant 1-forms of 3-dimensional Lie algebras up to constant scale factors. These factors are fixed in terms of the DJT coupling constant {mu}m which is the constant of proportionality between the Einstein and Cotton tensors in 3-dimensions. Differences between the scale factors result in anisotropy which is a common feature of topologically massive 3-manifolds. We have found that only Bianchi Types VI, VIII, and IX leadmore » to nontrivial solutions. Among these, a Bianchi Type IX, squashed 3-sphere solution of the Euclideanized DJT theory has finite action, Bianchi Type VIII, IX solutions can variously be embedded in the de Sitter/anti-de Sitter space. That is, some DJT 3-manifolds that we shall present here can be regarded as the basic constitent of anti-de Sitter space which is the ground state solution in higher dimensional generalizations of Einstein's general relativity. {copyright} 1989 Academic Press, Inc.« less

Einstein's 1919 View

NASA Astrophysics Data System (ADS)

Goradia, Shantilal

2012-10-01

When Rutherford discovered the nuclear force in 1919, he felt the force he discovered reflected some deviation of Newtonian gravity. Einstein too in his 1919 paper published the failure of the general relativity and Newtonian gravity to explain nuclear force and, in his concluding remarks, he retracted his earlier introduction of the cosmological constant. Consistent with his genius, we modify Newtonian gravity as probabilistic gravity using natural Planck units for a realistic study of nature. The result is capable of expressing both (1) nuclear force [strong coupling], and (2) Newtonian gravity in one equation, implying in general, in layman's words, that gravity is the cumulative effect of all quantum mechanical forces which are impossible to measure at long distances. Non discovery of graviton and quantum gravity silently support our findings. Continuing to climb on the shoulders of the giants enables us to see horizons otherwise unseen, as reflected in our book: ``Quantum Consciousness - The Road to Reality,'' and physics/0210040, where we derive the fine structure constant as a function of the age of the universe in Planck times consistent with Gamow's hint, using natural logarithm consistent with Feynman's hint.

Validity of the Stokes-Einstein relation in liquids: simple rules from the excess entropy.

PubMed

Pasturel, A; Jakse, N

2016-12-07

It is becoming common practice to consider that the Stokes-Einstein relation D/T~ η -1 usually works for liquids above their melting temperatures although there is also experimental evidence for its failure. Here we investigate numerically this commonly-invoked assumption for simple liquid metals as well as for their liquid alloys. Using ab initio molecular dynamics simulations we show how entropy scaling relationships developed by Rosenfeld can be used to predict the conditions for the validity of the Stokes-Einstein relation in the liquid phase. Specifically, we demonstrate the Stokes-Einstein relation may break down in the liquid phase of some liquid alloys mainly due to the presence of local structural ordering as evidenced in their partial two-body excess entropies. Our findings shed new light on the understanding of transport properties of liquid materials and will trigger more experimental and theoretical studies since excess entropy and its two-body approximation are readily obtainable from standard experiments and simulations.

The turning point for Einstein's Annus mirabilis

NASA Astrophysics Data System (ADS)

Rynasiewicz, Robert; Renn, Jürgen

The year 1905 has been called Einstein's Annus mirabilis because of three ground-breaking works completed over the span of a few months-the light-quantum paper, the Brownian motion paper, and the paper on the electrodynamics of moving bodies introducing the special theory of relativity. There are prima facie reasons for thinking that the origins of these papers cannot be understood in isolation from one another. Due to space limitations, we concentrate primarily on the light quantum paper, since, in key respects, it marks the turning point for the Annus mirabilis. The task is to probe, not just how the idea of the light quantum might have occurred to Einstein, but, more importantly, what convinced him that the idea was not just a quixotic hypothesis, but an unavoidable and demonstrable feature of radiation. The crucial development, we suggest, arose from comparing the energy fluctuations that follow rigorously from the Stefan-Boltzmann law, as well as from Wien's distribution formula for blackbody radiation, with what it is reasonable to expect from Maxwell's electromagnetic theory of light. A special case of this is addressed in Einstein's one paper from 1904, "Zur allgemeinen molekularen Theorie der Wärme". Annalen der Physik, 14, 355-362 (Also in CPAE, Vol. 2, Doc. 5)]. The outcome for the general case leads naturally to the central theoretical argument of the light quantum paper, the expectation of Brownian-like motion, and several of the key results for the electrodynamics of moving bodies.

On the existence of the field line solutions of the Einstein-Maxwell equations

NASA Astrophysics Data System (ADS)

Vancea, Ion V.

The main result of this paper is the proof that there are local electric and magnetic field configurations expressed in terms of field lines on an arbitrary hyperbolic manifold. This electromagnetic field is described by (dual) solutions of the Maxwell’s equations of the Einstein-Maxwell theory. These solutions have the following important properties: (i) they are general, in the sense that the knot solutions are particular cases of them and (ii) they reduce to the electromagnetic fields in the field line representation in the flat space-time. Also, we discuss briefly the real representation of these electromagnetic configurations and write down the corresponding Einstein equations.

Gravitomagnetism: From Einstein's 1912 Paper to the Satellites LAGEOS and Gravity Probe B

NASA Astrophysics Data System (ADS)

Pfister, Herbert

The first concrete calculations of (linear) gravitomagnetic effects were performed by Einstein in 1912-1913. Einstein also directly and decisively contributed to the "famous" papers by Thirring (and Lense) from 1918. Generalizations to strong fields were performed not earlier than in 1966 by Brill and Cohen. Extensions to higher orders of the angular velocity ω by Pfister and Braun (1985-1989) led to a solution of the centrifugal force problem and to a quasiglobal principle of equivalence. The difficulties but also the recent successes to measure gravitomagnetic effects are reviewed, and cosmological and Machian aspects of gravitomagnetism are discussed.

Book Review: Book review

NASA Astrophysics Data System (ADS)

Wegener, Daan

Writing a biography of a complex personality and mastermind like Albert Einstein is a daunting task for any historian of science. Yet the sheer temptation of writing his biography has apparently helped to overcome scholarly scruples, as biographies of Einstein have appeared quite regularly on the market. One of them is Einstein: his Life and Universe by journalist Walter Isaacson. It is a best-seller, which is one of the reasons the book deserves a critical evaluation. Isaacson is a man of considerable repute: he has been the chairman of CNN and managing editor of Time magazine. Isaacson's Einstein is written in a style that is accessible to a wide audience. Scholars who are already familiar with Einstein's physics may still enjoy the parts of the book that deal with the relation between Einstein and the press. Indeed, the breadth of its scope is the book's major merit, as it connects the personal, scientific, public and political dimensions of Einstein's life. In this review, I discuss Isaacson's treatment of these dimensions one-by-one.

Divergence identities in curved space-time a resolution of the stress-energy problem

NASA Astrophysics Data System (ADS)

Yilmaz, Hüseyin

1989-03-01

It is noted that the joint use of two basic differential identities in curved space-time, namely, 1) the Einstein-Hilbert identity (1915), and 2) the identity of P. Freud (1939), permits a viable alternative to general relativity and a resolution of the "field stress-energy" problem of the gravitational theory. (A tribute to Eugene P. Wigner's 1957 presidential address to the APS)

What is Gravitational Lensing?(LBNL Summer Lecture Series)

ScienceCinema

Alexie, Leauthaud; Reiko, Nakajima [Berkeley Center for Cosmological Physics, Berkely, California, United States

2017-12-09

July 28, 2009 Berkeley Lab summer lecture: Gravitational lensing is explained by Einstein's general theory of relativity: galaxies and clusters of galaxies, which are very massive objects, act on spacetime by causing it to become curved. Alexie Leauthaud and Reiko Nakajima, astrophysicists with the Berkeley Center for Cosmological Physics, will discuss how scientists use gravitational lensing to investigate the nature of dark energy and dark matter in the universe.

Explained in 60 Seconds: A collaboration with Symmetry Magazine, a Fermilab/SLAC publication

NASA Astrophysics Data System (ADS)

Trodden, M.

2011-07-01

The Big Bang refers to the start of the rapid expansion of our Universe. Edwin Hubble discovered this expansion in the 1920s through observations of faraway galaxies, showing that the distances between them are growing as time passes. This stunning discovery is beautifully explained by general relativity — Einstein's theory of gravity — augmented by two new concepts, dark matter and dark energy.

Gambling with the Universe

NASA Astrophysics Data System (ADS)

Hawking, Stephen

2002-05-01

This is an excerpt from Stephen Hawking's book The Universe in a Nutshell. Roger Penrose and Stephen Hawking, Lucasian Professor of Mathematics at the University of Cambridge, were able to show that Einstein's General Theory of Relativity implied that the universe and time itself must have had a beginning in a tremendous explosion. The discovery of the expansion of the universe is one of the great intellectual revolutions of the twentieth century.

The equivalence of Darmois-Israel and distributional method for thin shells in general relativity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mansouri, R.; Khorrami, M.

1996-11-01

A distributional method to solve the Einstein{close_quote}s field equations for thin shells is formulated. The familiar field equations and jump conditions of Darmois-Israel formalism are derived. A careful analysis of the Bianchi identities shows that, for cases under consideration, they make sense as distributions and lead to jump conditions of Darmois-Israel formalism. {copyright} {ital 1996 American Institute of Physics.}

Cosmological constant implementing Mach principle in general relativity

NASA Astrophysics Data System (ADS)

Namavarian, Nadereh; Farhoudi, Mehrdad

2016-10-01

We consider the fact that noticing on the operational meaning of the physical concepts played an impetus role in the appearance of general relativity (GR). Thus, we have paid more attention to the operational definition of the gravitational coupling constant in this theory as a dimensional constant which is gained through an experiment. However, as all available experiments just provide the value of this constant locally, this coupling constant can operationally be meaningful only in a local area. Regarding this point, to obtain an extension of GR for the large scale, we replace it by a conformal invariant model and then, reduce this model to a theory for the cosmological scale via breaking down the conformal symmetry through singling out a specific conformal frame which is characterized by the large scale characteristics of the universe. Finally, we come to the same field equations that historically were proposed by Einstein for the cosmological scale (GR plus the cosmological constant) as the result of his endeavor for making GR consistent with the Mach principle. However, we declare that the obtained field equations in this alternative approach do not carry the problem of the field equations proposed by Einstein for being consistent with Mach's principle (i.e., the existence of de Sitter solution), and can also be considered compatible with this principle in the Sciama view.

Relativity time-delay experiments utilizing 'Mariner' spacecraft

NASA Technical Reports Server (NTRS)

Esposito, P. B.; Anderson, J. D.

1974-01-01

Relativity predicts that the transit time of a signal propagated from the earth to a spacecraft and retransmitted back to earth ought to exhibit an additional, variable time delay. The present work describes some of the analytical techniques employed in experiments using Mariner spacecraft designed to test the accuracy of this prediction. Two types of data are analyzed in these relativity experiments; these include phase-coherent, two-way Doppler shift and round-trip, transit-time measurements. Results of Mariner 6 and 7 relativistic time-delay experiments are in agreement with Einstein's theory of general relativity with an uncertainty of 3%.

A precise extragalactic test of General Relativity.

PubMed

Collett, Thomas E; Oldham, Lindsay J; Smith, Russell J; Auger, Matthew W; Westfall, Kyle B; Bacon, David; Nichol, Robert C; Masters, Karen L; Koyama, Kazuya; van den Bosch, Remco

2018-06-22

Einstein's theory of gravity, General Relativity, has been precisely tested on Solar System scales, but the long-range nature of gravity is still poorly constrained. The nearby strong gravitational lens ESO 325-G004 provides a laboratory to probe the weak-field regime of gravity and measure the spatial curvature generated per unit mass, γ. By reconstructing the observed light profile of the lensed arcs and the observed spatially resolved stellar kinematics with a single self-consistent model, we conclude that γ = 0.97 ± 0.09 at 68% confidence. Our result is consistent with the prediction of 1 from General Relativity and provides a strong extragalactic constraint on the weak-field metric of gravity. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

CMB B-mode auto-bispectrum produced by primordial gravitational waves

NASA Astrophysics Data System (ADS)

Tahara, Hiroaki W. H.; Yokoyama, Jun'ichi

2018-01-01

Gravitational waves from inflation induce polarization patterns in the cosmic microwave background (CMB). It is known that there are only two types of non-Gaussianities of the gravitational waves in the most general covariant scalar field theory having second-order field equations, namely, generalized G-inflation. One originates from the inherent non-Gaussianity in general relativity, and the other from a derivative coupling between the Einstein tensor and the scalar field. We calculate polarization bispectra induced by these non-Gaussianities by transforming them into separable forms by virtue of the Laplace transformation. It is shown that future experiments can constrain the new one but cannot detect the general relativistic one.

Regulative feedback in pattern formation: towards a general relativistic theory of positional information.

PubMed

Jaeger, Johannes; Irons, David; Monk, Nick

2008-10-01

Positional specification by morphogen gradients is traditionally viewed as a two-step process. A gradient is formed and then interpreted, providing a spatial metric independent of the target tissue, similar to the concept of space in classical mechanics. However, the formation and interpretation of gradients are coupled, dynamic processes. We introduce a conceptual framework for positional specification in which cellular activity feeds back on positional information encoded by gradients, analogous to the feedback between mass-energy distribution and the geometry of space-time in Einstein's general theory of relativity. We discuss how such general relativistic positional information (GRPI) can guide systems-level approaches to pattern formation.

Left-invariant Einstein metrics on S3 ×S3

NASA Astrophysics Data System (ADS)

Belgun, Florin; Cortés, Vicente; Haupt, Alexander S.; Lindemann, David

2018-06-01

The classification of homogeneous compact Einstein manifolds in dimension six is an open problem. We consider the remaining open case, namely left-invariant Einstein metrics g on G = SU(2) × SU(2) =S3 ×S3. Einstein metrics are critical points of the total scalar curvature functional for fixed volume. The scalar curvature S of a left-invariant metric g is constant and can be expressed as a rational function in the parameters determining the metric. The critical points of S, subject to the volume constraint, are given by the zero locus of a system of polynomials in the parameters. In general, however, the determination of the zero locus is apparently out of reach. Instead, we consider the case where the isotropy group K of g in the group of motions is non-trivial. When K ≇Z2 we prove that the Einstein metrics on G are given by (up to homothety) either the standard metric or the nearly Kähler metric, based on representation-theoretic arguments and computer algebra. For the remaining case K ≅Z2 we present partial results.

The Einstein database of IPC x-ray observations of optically selected and radio-selected quasars, 1.

NASA Technical Reports Server (NTRS)

Wilkes, Belinda J.; Tananbaum, Harvey; Worrall, D. M.; Avni, Yoram; Oey, M. S.; Flanagan, Joan

1994-01-01

We present the first volume of the Einstein quasar database. The database includes estimates of the X-ray count rates, fluxes, and luminosities for 514 quasars and Seyfert 1 galaxies observed with the Imaging Proportional Counter (IPC) aboard the Einstein Observatory. All were previously known optically selected or radio-selected objects, and most were the targets of the X-ray observations. The X-ray properties of the Active Galactic Nuclei (AGNs) have been derived by reanalyzing the IPC data in a systematic manner to provide a uniform database for general use by the astronomical community. We use the database to extend earlier quasar luminosity studies which were made using only a subset of the currently available data. The database can be accessed on internet via the SAO Einstein on-line system ('Einline') and is available in ASCII format on magnetic tape and DOS diskette.

Quasi-local conserved charges in the Einstein-Maxwell theory

NASA Astrophysics Data System (ADS)

Setare, M. R.; Adami, H.

2017-05-01

In this paper we consider the Einstein-Maxwell theory and define a combined transformation composed of diffeomorphism and U(1) gauge transformation. For generality, we assume that the generator χ of such transformation is field-dependent. We define the extended off-shell ADT current and then off-shell ADT charge such that they are conserved off-shell for the asymptotically field-dependent symmetry generator χ. Then, we define the conserved charge corresponding to the asymptotically field-dependent symmetry generator χ. We apply the presented method to find the conserved charges of the asymptotically AdS3 spacetimes in the context of the Einstein-Maxwell theory in three dimensions. Although the usual proposal for the quasi local charges provides divergent global charges for the Einstein-Maxwell theory with negative cosmological constant in three dimensions, here we avoid this problem by introducing proposed combined transformation χ

Radiating black hole solutions in Einstein-Gauss-Bonnet gravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dominguez, Alfredo E.; Instituto Universitario Aeronautico, Avenida Fuerza Aerea km 6.5.; Gallo, Emanuel

2006-03-15

In this paper, we find some new exact solutions to the Einstein-Gauss-Bonnet equations. First, we prove a theorem which allows us to find a large family of solutions to the Einstein-Gauss-Bonnet gravity in n-dimensions. This family of solutions represents dynamic black holes and contains, as particular cases, not only the recently found Vaidya-Einstein-Gauss-Bonnet black hole, but also other physical solutions that we think are new, such as the Gauss-Bonnet versions of the Bonnor-Vaidya (de Sitter/anti-de Sitter) solution, a global monopole, and the Husain black holes. We also present a more general version of this theorem in which less restrictive conditionsmore » on the energy-momentum tensor are imposed. As an application of this theorem, we present the exact solution describing a black hole radiating a charged null fluid in a Born-Infeld nonlinear electrodynamics.« less

Interpretation of Mössbauer experiment in a rotating system: A new proof for general relativity

NASA Astrophysics Data System (ADS)

Corda, Christian

2015-04-01

A historical experiment by Kündig on the transverse Doppler shift in a rotating system measured with the Mössbauer effect (Mössbauer rotor experiment) has been recently first re-analyzed and then replied by an experimental research group. The results of re-analyzing the experiment have shown that a correct re-processing of Kündig's experimental data gives an interesting deviation of a relative redshift between emission and absorption resonant lines from the standard prediction based on the relativistic dilatation of time. That prediction gives a redshift ∇E/E ≃ -1/2 v2/c2 where v is the tangential velocity of the absorber of resonant radiation, c is the velocity of light in vacuum and the result is given to the accuracy of first-order in v2/c2. Data re-processing gave ∇E/E ≃ - kv2/c2 with k = 0.596 ± 0.006. Subsequent new experimental results by the reply of Kündig experiment have shown a redshift with k = 0.68 ± 0.03 instead. By using Einstein Equivalence Principle, which states the equivalence between the gravitational "force" and the pseudo-force experienced by an observer in a non-inertial frame of reference (included a rotating frame of reference) here we re-analyze the theoretical framework of Mössbauer rotor experiments directly in the rotating frame of reference by using a general relativistic treatment. It will be shown that previous analyses missed an important effect of clock synchronization and that the correct general relativistic prevision in the rotating frame gives k ≃ 2/3 in perfect agreement with the new experimental results. Such an effect of clock synchronization has been missed in various papers in the literature with some subsequent claim of invalidity of relativity theory and/or some attempts to explain the experimental results through "exotic" effects. Our general relativistic interpretation shows, instead, that the new experimental results of the Mössbauer rotor experiment are a new, strong and independent, proof of Einstein general relativity. In the final section of the paper we discuss an analogy with the use of General Relativity in Global Positioning Systems.

On the validity of Stokes-Einstein and Stokes-Einstein-Debye relations in ionic liquids and ionic-liquid mixtures.

PubMed

Köddermann, Thorsten; Ludwig, Ralf; Paschek, Dietmar

2008-09-15

Stokes-Einstein (SE) and Stokes-Einstein-Debye (SED) relations in the neat ionic liquid (IL) [C(2)mim][NTf(2)] and IL/chloroform mixtures are studied by means of molecular dynamics (MD) simulations. For this purpose, we simulate the translational diffusion coefficients of the cations and anions, the rotational correlation times of the C(2)--H bond in the cation C(2)mim(+), and the viscosities of the whole system. We find that the SE and SED relations are not valid for the pure ionic liquid, nor for IL/chloroform mixtures down to the miscibility gap (at 50 wt % IL). The deviations from both relations could be related to dynamical heterogeneities described by the non-Gaussian parameter alpha(t). If alpha(t) is close to zero, at a concentration of 1 wt % IL in chloroform, both relations become valid. Then, the effective radii and volumes calculated from the SE and SED equations can be related to the structures found in the MD simulations, such as aggregates of ion pairs. Overall, similarities are observed between the dynamical properties of supercooled water and those of ionic liquids.

Einstein's Theory Fights off Challengers

NASA Astrophysics Data System (ADS)

2010-04-01

Two new and independent studies have put Einstein's General Theory of Relativity to the test like never before. These results, made using NASA's Chandra X-ray Observatory, show Einstein's theory is still the best game in town. Each team of scientists took advantage of extensive Chandra observations of galaxy clusters, the largest objects in the Universe bound together by gravity. One result undercuts a rival gravity model to General Relativity, while the other shows that Einstein's theory works over a vast range of times and distances across the cosmos. The first finding significantly weakens a competitor to General Relativity known as "f(R) gravity". "If General Relativity were the heavyweight boxing champion, this other theory was hoping to be the upstart contender," said Fabian Schmidt of the California Institute of Technology in Pasadena, who led the study. "Our work shows that the chances of its upsetting the champ are very slim." In recent years, physicists have turned their attention to competing theories to General Relativity as a possible explanation for the accelerated expansion of the universe. Currently, the most popular explanation for the acceleration is the so-called cosmological constant, which can be understood as energy that exists in empty space. This energy is referred to as dark energy to emphasize that it cannot be directly detected. In the f(R) theory, the cosmic acceleration comes not from an exotic form of energy but from a modification of the gravitational force. The modified force also affects the rate at which small enhancements of matter can grow over the eons to become massive clusters of galaxies, opening up the possibility of a sensitive test of the theory. Schmidt and colleagues used mass estimates of 49 galaxy clusters in the local universe from Chandra observations, and compared them with theoretical model predictions and studies of supernovas, the cosmic microwave background, and the large-scale distribution of galaxies. They found no evidence that gravity is different from General Relativity on scales larger than 130 million light years. This limit corresponds to a hundred-fold improvement on the bounds of the modified gravitational force's range that can be set without using the cluster data. "This is the strongest ever constraint set on an alternative to General Relativity on such large distance scales," said Schmidt. "Our results show that we can probe gravity stringently on cosmological scales by using observations of galaxy clusters." The reason for this dramatic improvement in constraints can be traced to the greatly enhanced gravitational forces acting in clusters as opposed to the universal background expansion of the universe. The cluster-growth technique also promises to be a good probe of other modified gravity scenarios, such as models motivated by higher-dimensional theories and string theory. A second, independent study also bolsters General Relativity by directly testing it across cosmological distances and times. Up until now, General Relativity had been verified only using experiments from laboratory to Solar System scales, leaving the door open to the possibility that General Relativity breaks down on much larger scales. To probe this question, a group at Stanford University compared Chandra observations of how rapidly galaxy clusters have grown over time to the predictions of General Relativity. The result is nearly complete agreement between observation and theory. "Einstein's theory succeeds again, this time in calculating how many massive clusters have formed under gravity's pull over the last five billion years," said David Rapetti of the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) at Stanford University and SLAC National Accelerator Laboratory, who led the new study. "Excitingly and reassuringly, our results are the most robust consistency test of General Relativity yet carried out on cosmological scales." Rapetti and his colleagues based their results on a sample of 238 clusters detected across the whole sky by the now-defunct ROSAT X-ray telescope. These data were enhanced by detailed mass measurements for 71 distant clusters using Chandra, and 23 relatively nearby clusters using ROSAT, and combined with studies of supernovas, the cosmic microwave background, the distribution of galaxies and distance estimates to galaxy clusters. Galaxy clusters are important objects in the quest to understand the Universe as a whole. Because the observations of the masses of galaxy clusters are directly sensitive to the properties of gravity, they provide crucial information. Other techniques such as observations of supernovas or the distribution of galaxies measure cosmic distances, which depend only on the expansion rate of the universe. In contrast, the cluster technique used by Rapetti and his colleagues measure in addition the growth rate of the cosmic structure, as driven by gravity. "Cosmic acceleration represents a great challenge to our modern understanding of physics," said Rapetti's co-author Adam Mantz of NASA's Goddard Space Flight Center in Maryland. "Measurements of acceleration have highlighted how little we know about gravity at cosmic scales, but we're now starting to push back our ignorance." The paper by Fabian Schmidt was published in Physics Review D, Volume 80 in October 2009 and is co-authored by Alexey Vikhlinin of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and Wayne Hu of the University of Chicago, Illinois. The paper by David Rapetti was recently accepted for publication in the Monthly Notices of the Royal Astronomical Society and is co-authored by Mantz, Steve Allen of KIPAC at Stanford and Harald Ebeling of the Institute for Astronomy in Hawaii. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass. More information, including images and other multimedia, can be found at: http://chandra.harvard.edu and http://chandra.nasa.gov

Conserved Quantities in General Relativity: From the Quasi-Local Level to Spatial Infinity

NASA Astrophysics Data System (ADS)

Chen, Po-Ning; Wang, Mu-Tao; Yau, Shing-Tung

2015-08-01

We define quasi-local conserved quantities in general relativity by using the optimal isometric embedding in Wang and Yau (Commun Math Phys 288(3):919-942, 2009) to transplant Killing fields in the Minkowski spacetime back to the 2-surface of interest in a physical spacetime. To each optimal isometric embedding, a dual element of the Lie algebra of the Lorentz group is assigned. Quasi-local angular momentum and quasi-local center of mass correspond to pairing this element with rotation Killing fields and boost Killing fields, respectively. They obey classical transformation laws under the action of the Poincaré group. We further justify these definitions by considering their limits as the total angular momentum and the total center of mass of an isolated system. These expressions were derived from the Hamilton-Jacobi analysis of the gravitational action and thus satisfy conservation laws. As a result, we obtained an invariant total angular momentum theorem in the Kerr spacetime. For a vacuum asymptotically flat initial data set of order 1, it is shown that the limits are always finite without any extra assumptions. We also study these total conserved quantities on a family of asymptotically flat initial data sets evolving by the vacuum Einstein evolution equation. It is shown that the total angular momentum is conserved under the evolution. For the total center of mass, the classical dynamical formula relating the center of mass, energy, and linear momentum is recovered, in the nonlinear context of initial data sets evolving by the vacuum Einstein evolution equation. The definition of quasi-local angular momentum provides an answer to the second problem in classical general relativity on Penrose's list (Proc R Soc Lond Ser A 381(1780):53-63, 1982).

Einstein's Mirror

ERIC Educational Resources Information Center

Gjurchinovski, Aleksandar; Skeparovski, Aleksandar

2008-01-01

Reflection of light from a plane mirror in uniform rectilinear motion is a century-old problem, intimately related to the foundations of special relativity. The problem was first investigated by Einstein in his famous 1905 paper by using the Lorentz transformations to switch from the mirror's rest frame to the frame where the mirror moves at a…

Pure connection formulation, twistors, and the chase for a twistor action for general relativity

NASA Astrophysics Data System (ADS)

Herfray, Yannick

2017-11-01

This paper establishes the relation between traditional results from the (Euclidean) twistor theory and chiral formulations of general relativity (GR), especially the pure connection formulation. Starting from an SU(2)-connection only, we show how to construct natural complex data on twistor space, mainly an almost Hermitian structure and a connection on some complex line bundle. Only when this almost Hermitian structure is integrable is the connection related to an anti-self-dual-Einstein metric and makes contact with the usual results. This leads to a new proof of the non-linear graviton theorem. Finally, we discuss what new strategies this "connection approach" to twistors suggests for constructing a twistor action for gravity. In Appendix A, we also review all known chiral Lagrangians for GR.

Einstein and Planck

NASA Astrophysics Data System (ADS)

Heilbron, John

2005-03-01

As an editor of the Annalen der Physik, Max Planck published Einstein's early papers on thermodynamics and on special relativity, which Planck probably was the first major physicist to appreciate. They respected one another not only as physicists but also, for their inspired creation of world pictures, as artists. Planck helped to establish Einstein in a sinecure at the center of German physics, Berlin. Despite their differences in scientific style, social life, politics, and religion, they became fast friends. Their mutual admiration survived World War I, during which Einstein advocated pacifism and Planck signed the infamous Manifesto of the 93 Intellectuals supporting the German invasion of Belgium. It also survived the Weimar Republic, which Einstein favored and Planck disliked. Physics drew them together, as both opposed the Copenhagen Interpretation; so did common decency, as Planck helped to protect Einstein from anti-semitic attacks. Their friendship did not survive the Nazis. As a standing secretary of the Berlin Academy, Planck had to advise Einstein to resign from it before his colleagues, outraged at his criticism of the new Germany from the safety of California, expelled him. Einstein never forgave his old friend and former fellow artist for not protesting publicly against his expulsion and denigration, and other enormities of National Socialism. .

Constraining the noncommutative spectral action via astrophysical observations.

PubMed

Nelson, William; Ochoa, Joseph; Sakellariadou, Mairi

2010-09-03

The noncommutative spectral action extends our familiar notion of commutative spaces, using the data encoded in a spectral triple on an almost commutative space. Varying a rather simple action, one can derive all of the standard model of particle physics in this setting, in addition to a modified version of Einstein-Hilbert gravity. In this Letter we use observations of pulsar timings, assuming that no deviation from general relativity has been observed, to constrain the gravitational sector of this theory. While the bounds on the coupling constants remain rather weak, they are comparable to existing bounds on deviations from general relativity in other settings and are likely to be further constrained by future observations.

Hidden Symmetries of Euclideanised Kerr-NUT-(A)dS Metrics in Certain Scaling Limits

NASA Astrophysics Data System (ADS)

Visinescu, Mihai; Vîlcu, Eduard

2012-08-01

The hidden symmetries of higher dimensional Kerr-NUT-(A)dS metrics are investigated. In certain scaling limits these metrics are related to the Einstein-Sasaki ones. The complete set of Killing-Yano tensors of the Einstein-Sasaki spaces are presented. For this purpose the Killing forms of the Calabi-Yau cone over the Einstein-Sasaki manifold are constructed. Two new Killing forms on Einstein-Sasaki manifolds are identified associated with the complex volume form of the cone manifolds. Finally the Killing forms on mixed 3-Sasaki manifolds are briefly described.

The member of the Academy H.P. Keres and the Relativity theory in Estonia

NASA Astrophysics Data System (ADS)

Kuusk, P.; Muursepp, P. V.; Piir, Ivar

1987-10-01

The first popular lecture on the Einstein theory of relativity was given in Estonia already in 1914 by Jaan Sarv (1877-1954)[1],afterwards a professor of mathematics at the Tartu University. The first student courses on special relativity were delivered by Professor of Mathematics Juri Nuut (1892-1952): non-Euclidean geometry (1930), the mathematical theory of relativity (1932/1933),the Lorenz transformations (1937). His own research work concerned the Lobachevsky geometry [7] and its application to cosmology [6]. Harald Keres qraguated from the Tartu University in 1936. He gave the first student course on general relativity (based on books [11-14]in 1940.In 1942,he got the dr.phil.nat degree form the Tartu University for his theses "Raum und Zeit in der allgemeinen Relativitatstheorie". The degree of the doctor of mathematical and physical sciences was confirmed by VAK (the All-Union Higher Attestation Commission) in 1949.In this period, he got aquainted with the leading Soviet scientists working on General Relativity, prof.V.A.Fock,Prof.D.D.Ivanenko,Prof.A.Z.Petrov,and Prof.M.F.Shirokov. After World War two all-union university courses were introduced in Tartu State University. According to the curriculum of the course the special theory of relativity is a part of electrodynamics obligatory for all students of the department of Physics. From 1947 till 1985 this course was delivered by Prof.PaulKard(1914-1985).He also published a number of text-books on the subject [15-19]. The general theory of relativity was read by Prof.H.Keres in 1951-1960 and later by his pupils R.Lias and A.Koppel [20-23] as a special course for students specializing in theoretical Physics. The first PHD-s in general relativity were made by R.Lias [27](1954) and I.Piir [28] (1955). In 1961, Prof.H.Keres was elected a member of the Academy of Sciences of the Estonian S.S.R. He left the TArtu State University and began to work in the Institute of Physics as the head of the Department of THeoretical Physics.His main scientific works [35-40]were made in the sixties.In his works he introduced inertial systems that can be used in the Einstein theory as well as in the Newton theory of gravitation.these systems are determined by freely falling particles and clocks and cannot be realized as a rigid frame of references. In these frames, the non-relativistic Newtonian theory can be considered as a limit of the relativistic Einstein theory. Currently the main directions of the research on general relativity in Tartu are the following: 1) connections between the relativistic and non-relativistic theories of gravitation and the corresponding exact solutions (A.Koppel), 2) radiation fields fields in a curved space-time,especially the propagation and detection of gravitational waves (I.Piir,V.Unt, R.Tamello, R.Mankin). The modern trends in theoretical physics are represented by the investigations in supergravity,curved superspace and superstrings (P.Kuusk). A detailed history of the research work on cosmology in Estonia is the subject of a subsequent paper.

Existence of topological multi-string solutions in Abelian gauge field theories

NASA Astrophysics Data System (ADS)

Han, Jongmin; Sohn, Juhee

2017-11-01

In this paper, we consider a general form of self-dual equations arising from Abelian gauge field theories coupled with the Einstein equations. By applying the super/subsolution method, we prove that topological multi-string solutions exist for any coupling constant, which improves previously known results. We provide two examples for application: the self-dual Einstein-Maxwell-Higgs model and the gravitational Maxwell gauged O(3) sigma model.

Exact solutions to quadratic gravity

NASA Astrophysics Data System (ADS)

Pravda, V.; Pravdová, A.; Podolský, J.; Švarc, R.

2017-04-01

Since all Einstein spacetimes are vacuum solutions to quadratic gravity in four dimensions, in this paper we study various aspects of non-Einstein vacuum solutions to this theory. Most such known solutions are of traceless Ricci and Petrov type N with a constant Ricci scalar. Thus we assume the Ricci scalar to be constant which leads to a substantial simplification of the field equations. We prove that a vacuum solution to quadratic gravity with traceless Ricci tensor of type N and aligned Weyl tensor of any Petrov type is necessarily a Kundt spacetime. This will considerably simplify the search for new non-Einstein solutions. Similarly, a vacuum solution to quadratic gravity with traceless Ricci type III and aligned Weyl tensor of Petrov type II or more special is again necessarily a Kundt spacetime. Then we study the general role of conformal transformations in constructing vacuum solutions to quadratic gravity. We find that such solutions can be obtained by solving one nonlinear partial differential equation for a conformal factor on any Einstein spacetime or, more generally, on any background with vanishing Bach tensor. In particular, we show that all geometries conformal to Kundt are either Kundt or Robinson-Trautman, and we provide some explicit Kundt and Robinson-Trautman solutions to quadratic gravity by solving the above mentioned equation on certain Kundt backgrounds.

Gravity Probe B: Testing Einstein with Gyroscopes

NASA Technical Reports Server (NTRS)

Geveden, Rex D.; May, Todd

2003-01-01

Some 40 years in the making, NASA' s historic Gravity Probe B (GP-B) mission is scheduled to launch aboard a Delta II in 2003. GP-B will test two extraordinary predictions from Einstein's General Relativity: geodetic precession and the Lense-Thirring effect (frame-dragging). Employing tiny, ultra-precise gyroscopes, GP-B features a measurement accuracy of 0.5 milli-arc-seconds per year. The extraordinary measurement precision is made possible by a host of breakthrough technologies, including electro-statically suspended, super-conducting quartz gyroscopes; virtual elimination of magnetic flux; a solid quartz star tracking telescope; helium microthrusters for drag-free control of the spacecraft; and a 2400 liter superfluid helium dewar. This paper will provide an overview of the science, key technologies, flight hardware, integration and test, and flight operations of the GP-B space vehicle. It will also examine some of the technical management challenges of a large-scale, technology-driven, Principal Investigator-led mission.

Gravity Probe B: Testing Einstein with Gyroscopes

NASA Technical Reports Server (NTRS)

Geveden, Rex D.; May, Todd

2003-01-01

Some 40 years in the making, NASA s historic Gravity Probe B (GP-B) mission is scheduled to launch aboard a Delta I1 in 2003. GP-B will test two extraordinary predictions from Einstein s General Relativity: geodetic precession and the Lense-Thirring effect (frame-dragging). Employing tiny, ultra-precise gyroscopes, GP-B features a measurement accuracy of 0.5 milli-arc-seconds per year. The extraordinary measurement precision is made possible by a host of breakthrough technologies, including electro-statically suspended, super-conducting quartz gyroscopes; virtual elimination of magnetic flux; a solid quartz star- tracking telescope; helium microthrusters for drag-free control of the spacecraft; and a 2400 liter superfluid helium dewar. This paper will provide an overview of the science, key technologies, flight hardware, integration and test, and flight operations of the GP-B space vehicle. It will also examine some of the technical management challenges of a large-scale, technology-driven, Principal Investigator-led mission.

Dark matter influence on black objects thermodynamics

NASA Astrophysics Data System (ADS)

Rogatko, Marek; Wojnar, Aneta

2018-05-01

Physical process version of the first law of black hole thermodynamics in Einstein-Maxwell dark matter gravity was derived. The dark matter sector is mimicked by the additional U(1)-gauge field coupled to the ordinary Maxwell one. By considering any cross section of the black hole event horizon to the future of the bifurcation surface, the equilibrium state version of the first law of black hole mechanics was achieved. The considerations were generalized to the case of Einstein-Yang-Mills dark matter gravity theory. The main conclusion is that the influence of dark matter is crucial in the formation process of black objects. This fact may constitute the explanation of the recent observations of the enormous mass of the super luminous quasars formed in a relatively short time after Big Bang. We also pay attention to the compact binaries thermodynamics, when dark matter sector enters the game.

Generalized quasitopological gravity

NASA Astrophysics Data System (ADS)

Hennigar, Robie A.; KubizÅák, David; Mann, Robert B.

2017-05-01

We construct the most general, to cubic order in curvature, theory of gravity whose (most general) static spherically symmetric vacuum solutions are fully described by a single field equation. The theory possesses the following remarkable properties: (i) It has a well-defined Einstein gravity limit, (ii) it admits "Schwarzschild-like" solutions characterized by a single metric function, (iii) on maximally symmetric backgrounds it propagates the same degrees of freedom as Einstein's gravity, and (iv) Lovelock and quasitopological gravities, as well as the recently developed Einsteinian cubic gravity [Bueno and Cano Phys. Rev. D 94, 104005 (2016)., 10.1103/PhysRevD.94.104005] in four dimensions, are recovered as special cases. We perform a brief analysis of asymptotically flat black holes in this theory and study their thermodynamics.

5D Super Yang-Mills on Y p, q Sasaki-Einstein Manifolds

NASA Astrophysics Data System (ADS)

Qiu, Jian; Zabzine, Maxim

2015-01-01

On any simply connected Sasaki-Einstein five dimensional manifold one can construct a super Yang-Mills theory which preserves at least two supersymmetries. We study the special case of toric Sasaki-Einstein manifolds known as Y p, q manifolds. We use the localisation technique to compute the full perturbative part of the partition function. The full equivariant result is expressed in terms of a certain special function which appears to be a curious generalisation of the triple sine function. As an application of our general result we study the large N behaviour for the case of single hypermultiplet in adjoint representation and we derive the N 3-behaviour in this case.

Stationary solutions for the nonlinear Schrödinger equation modeling three-dimensional spherical Bose-Einstein condensates in general potentials.

PubMed

Mallory, Kristina; Van Gorder, Robert A

2015-07-01

Stationary solutions for the cubic nonlinear Schrödinger equation modeling Bose-Einstein condensates (BECs) confined in three spatial dimensions by general forms of a potential are studied through a perturbation method and also numerically. Note that we study both repulsive and attractive BECs under similar frameworks in order to deduce the effects of the potentials in each case. After outlining the general framework, solutions for a collection of specific confining potentials of physical relevance to experiments on BECs are provided in order to demonstrate the approach. We make several observations regarding the influence of the particular potentials on the behavior of the BECs in these cases, comparing and contrasting the qualitative behavior of the attractive and repulsive BECs for potentials of various strengths and forms. Finally, we consider the nonperturbative where the potential or the amplitude of the solutions is large, obtaining various qualitative results. When the kinetic energy term is small (relative to the nonlinearity and the confining potential), we recover the expected Thomas-Fermi approximation for the stationary solutions. Naturally, this also occurs in the large mass limit. Through all of these results, we are able to understand the qualitative behavior of spherical three-dimensional BECs in weak, intermediate, or strong confining potentials.

Quantum Emulation of Gravitational Waves.

PubMed

Fernandez-Corbaton, Ivan; Cirio, Mauro; Büse, Alexander; Lamata, Lucas; Solano, Enrique; Molina-Terriza, Gabriel

2015-07-14

Gravitational waves, as predicted by Einstein's general relativity theory, appear as ripples in the fabric of spacetime traveling at the speed of light. We prove that the propagation of small amplitude gravitational waves in a curved spacetime is equivalent to the propagation of a subspace of electromagnetic states. We use this result to propose the use of entangled photons to emulate the evolution of gravitational waves in curved spacetimes by means of experimental electromagnetic setups featuring metamaterials.

Impact of space on science

NASA Technical Reports Server (NTRS)

Elachi, Charles

1993-01-01

The advent of the capability to conduct space-based measurements has revolutionized the study of the Earth, the planetary system and the astrophysical universe. The resultant knowledge has yielded insights into the management of our planet's resources and provides intellectual enrichment for our civilization. New investigation techniques hold promise for extending the scope of space science to address topics in fundamental physics such as gravitational waves and certain aspects of Einstein's Theory of General Relativity.

Nonstatic radiating spheres in general relativity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krori, K.D.; Borgohain, P.; Sarma, R.

1985-02-15

The method of Herrera, Jimenez, and Ruggeri of obtaining nonstatic solutions of Einstein's field equations to study the evolution of stellar bodies is applied to obtain two models of nonstatic radiating spheres from two well-known static solutions of field equations, viz., Tolman's solutions IV and V. Whereas Tolman's type-IV model is found to be contracting for the period under investigation, Tolman's type-V model shows a bounce after attaining a minimum radius.

Introduction to some fundamental concepts of general relativity and to their required use in some modern timekeeping systems

NASA Technical Reports Server (NTRS)

Alley, C. O.

1982-01-01

Einstein's theory of gravity as curved space-time is presented. Emphasis is on the physical concepts, using only elementary mathematics. For the slow motions and weak gravitational fields experienced on Earth, the main curvature is that of time, not space. Experiments demonstrating this property are reviewed. The fundamental effects of motion and gravitational potential on clocks in many practical situations are discussed.

Lienard--Wiechert fields and general relativity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Newman, E.T.

1974-01-01

An analogy is extablished between the Lienard-Weichart solutions of the Maxwell equations and the Robinson-Trautman solutions of the einstein equations by virtue of the fact that a principal null vector field of either the Maxwell or Weyl tensor in each case satisfies the following four conditions: (1) The field is a geodesic field, (2) it has nonvanishing divergence, (3) it is shear free, and (4) it is twist (or curl) free. (auth)

Equilibrium distribution of heavy quarks in fokker-planck dynamics

PubMed

Walton; Rafelski

2000-01-03

We obtain an explicit generalization, within Fokker-Planck dynamics, of Einstein's relation between drag, diffusion, and the equilibrium distribution for a spatially homogeneous system, considering both the transverse and longitudinal diffusion for dimension n>1. We provide a complete characterization of the equilibrium distribution in terms of the drag and diffusion transport coefficients. We apply this analysis to charm quark dynamics in a thermal quark-gluon plasma for the case of collisional equilibration.

Sommerfeld's influence on Einstein's evaluation of Minkowski, 1908 to 1916

NASA Astrophysics Data System (ADS)

Smith, Felix T.

2016-03-01

Einstein (E.), who had begun entirely hostile to Minkowski's (M.'s) space-time view of relativity in 1908, completely reversed himself by March 1916, saying in the second sentence of his major article on General Relativity (G.R.) in Ann. d. Phys.: ``The generalization of the theory of relativity was greatly facilitated through the form that the special theory of relativity was given by Minkowski, the mathematician who first made clear the formal equivalence of the spatial coordinates and the time coordinate and made it practically useable for the construction of the theory.'' Two major steps in this evolution exhibit E.'s respect for Sommerfeld's (S.'s) knowledge and judgment. At a meeting in Salzburg, Sept., 1909, they discussed and disagreed strongly about the value of M.'s contributions, but by the Feb., 1910, Part 2 of a survey paper E. had come to follow S. in accepting fully M.'s space-time and its coordinate x4 = ict . Step 2 followed S.'s June, 1915, publication of a 1907 lecture on relativity by M., doctoring it slightly to influence E. Unknown is whatever else S. communicated to E. at that time, but S.'s unrivalled knowledge of the implications of M.'s 4-vector algebra and analysis were at E.'s disposal. There soon followed both a paper by E. in Feb., 1916, adapting to the needs of G.R. a covariant form of Maxwell's equations discovered by M., and then E.'s handsome acknowledgement in March. The importance of early personality issues between M. and E. and of S.'s later diplomatic interventions will be explored.

The Media of Relativity: Einstein and Telecommunications Technologies.

PubMed

Canales, Jimena

2015-07-01

How are fundamental constants, such as "c" for the speed of light, related to the technological environments that produce them? Relativistic cosmology, developed first by Albert Einstein, depended on military and commercial innovations in telecommunications. Prominent physicists (Hans Reichenbach, Max Born, Paul Langevin, Louis de Broglie, and Léon Brillouin, among others) worked in radio units during WWI and incorporated battlefield lessons into their research. Relativity physicists, working at the intersection of physics and optics by investigating light and electricity, responded to new challenges by developing a novel scientific framework. Ideas about lengths and solid bodies were overhauled because the old Newtonian mechanics assumed the possibility of "instantaneous signaling at a distance." Einstein's universe, where time and space dilated, where the shortest path between two points was often curved and non-Euclidean, followed the rules of electromagnetic "signal" transmission. For these scientists, light's constant speed in the absence of a gravitational field-a fundamental tenet of Einstein's theory-was a lesson derived from communication technologies.

Extensions of the Einstein-Schrodinger non-symmetric theory of gravity

NASA Astrophysics Data System (ADS)

Shifflett, James A.

We modify the Einstein-Schrödinger theory to include a cosmological constant L z which multiplies the symmetric metric. The cosmological constant L z is assumed to be nearly cancelled by Schrödinger's cosmological constant L b which multiplies the nonsymmetric fundamental tensor, such that the total L = L z + L b matches measurement. The resulting theory becomes exactly Einstein-Maxwell theory in the limit as |L z | [arrow right] oo. For |L z | ~ 1/(Planck length) 2 the field equations match the ordinary Einstein and Maxwell equations except for extra terms which are < 10 -16 of the usual terms for worst-case field strengths and rates-of-change accessible to measurement. Additional fields can be included in the Lagrangian, and these fields may couple to the symmetric metric and the electromagnetic vector potential, just as in Einstein-Maxwell theory. The ordinary Lorentz force equation is obtained by taking the divergence of the Einstein equations when sources are included. The Einstein- Infeld-Hoffmann (EIH) equations of motion match the equations of motion for Einstein-Maxwell theory to Newtonian/Coulombian order, which proves the existence of a Lorentz force without requiring sources. An exact charged solution matches the Reissner-Nordström solution except for additional terms which are ~ 10 -66 of the usual terms for worst-case radii accessible to measurement. An exact electromagnetic plane-wave solution is identical to its counterpart in Einstein-Maxwell theory. Peri-center advance, deflection of light and time delay of light have a fractional difference of < 10 -56 compared to Einstein-Maxwell theory for worst-case parameters. When a spin-1/2 field is included in the Lagrangian, the theory gives the ordinary Dirac equation, and the charged solution results in fractional shifts of < 10 -50 in Hydrogen atom energy levels. Newman-Penrose methods are used to derive an exact solution of the connection equations, and to show that the charged solution is Petrov type- D like the Reissner-Nordström solution. The Newman-Penrose asymptotically flat [Special characters omitted.] (1/ r 2 ) expansion of the field equations is shown to match Einstein-Maxwell theory. Finally we generalize the theory to non-Abelian fields, and show that a special case of the resulting theory closely approximates Einstein-Weinberg-Salam theory.

BOOK REVIEW: Einstein's Jury: The Race to Test Relativity

NASA Astrophysics Data System (ADS)

Ehlers, Jürgen

2007-10-01

'I know very well that my theory rests on a shaky foundation. What attracts me to it is that it leads to consequences that seem to be accessible to experiment, and it provides a starting point for the theoretical understanding of gravitation', wrote Einstein in 1911. Einstein's Jury by Jeffrey Crelinsten—well documented, well written, and fascinating to read—describes how, from 1909 on, Einstein's two theories of relativity became known to astronomers, and how the predictions made between 1907 and 1915 were received as challenges to observers. The author gives a non-technical account of the efforts made until 1930 to test these predictions; he focuses on two of the three classical tests, namely gravitational redshift and bending of light; the 'jury' consists mainly of American observers—Adams, Campbell, Curtis, Hale, Perrin, St John, Trumpler and others—working with newly built large telescopes, and the Britons Eddington and Evershed. The major steps which, after a long struggle, convinced the majority of astronomers that Einstein was right, are narrated chronologically in rather great detail, especially the work at Lick Observatory, before and after the famous British observation of 1919, on solar eclipses, and the work at Mount Wilson and the Indian Kodaikanal Observatories to extract the gravitational redshift from the complicated spectrum of the sun. The account of the eclipse work which was carried out between 1918 and 1923 by Lick astronomers corrects the impression suggested by many historical accounts that the British expedition alone settled the light-bending question. Apart from these main topics, the anomalous perihelion advance of Mercury and the ether problem are covered. By concentrating on astronomy rather than on physics this book complements the rich but repetitive literature on Einstein and relativity which appeared in connection with the commemoration of Einstein's annus mirabilis, 2005. The well told stories include curiosities such as the Vulcan hypothesis, Evershed's Earth effect, and D C Miller's ether drift experiments. In particular, the sections on the history of the Californian observatories, their leading personalities, the differing attitudes of American and European scientists, and the influence of World War 1 on science, add interesting and informative aspects to the narrative. Those sections which report logistic and instrumental details of, for example, eclipse expeditions, were (to me) somewhat tiring. A weakness seems to be that the scientific importance of relativity problems is not stated clearly. On p43, the reader learns that Curtis quoted de Sitter's theoretical result of 7.15'' per century for Mercury's anomalous perihelion shift, but it is not mentioned that this value was due only to the special-relativistic variation of mass with velocity and already known to be much smaller than the observed value given on p88 and explained by general relativity, which includes, in particular, space curvature. In connection with light bending, the 'factor 2' is mentioned in several places without the explanation that this doubling is due to space curvature, the principal new effect whose observation created such a stir in 1919. Moreover, technical terms, for example absolute space, inertial frame, state of rest and (anomalous) dispersion, are used without explanation. Besides, readers interested as much in science as in its history would probably have appreciated a brief account of the present state of knowledge concerning the issues treated in this book and related ones. There are a few deplorable errors, for example the spectrum of the Andromeda nebula is shifted not towards the red, but towards the blue (p12); Eddington's limb deflection is given (p144) as 0.61'', while the correct value is 1.61''; misprints like that on p147 (coefficient of dr²), mistaking the astronomer Soldner (not Solden) for a physicist (p164). On p34 one reads 'Minkowski did not really grasp the physical implications of Einstein's work'—a strange judgment which contradicts the historical record. Thus readers looking for explanations of scientific statements in a historical context may be less satisfied. Those interested in the history and sociology of science, its organizations, the role of leading figures as well as their critics and the difficult process of how scientists establish 'facts', will enjoy reading this book and should profit from it. An 'Einstein's Jury' of today would have more evidence for a positive verdict, but also reasons for new skepticism.

BOOK REVIEW Cracking the Einstein Code: Relativity and the Birth of Black Hole Physics With an Afterword by Roy Kerr Cracking the Einstein Code: Relativity and the Birth of Black Hole Physics With an Afterword by Roy Kerr

NASA Astrophysics Data System (ADS)

Carr, Bernard

2011-02-01

General relativity is arguably the most beautiful scientific theory ever conceived but its status within mainstream physics has vacillated since it was proposed in 1915. It began auspiciously with the successful explanation of the precession of Mercury and the dramatic confirmation of light-bending in the 1919 solar eclipse expedition, which turned Einstein into an overnight celebrity. Though little noticed at the time, there was also Karl Schwarzschild's discovery of the spherically symmetric solution in 1916 (later used to predict the existence of black holes) and Alexander Friedmann's discovery of the cosmological solution in 1922 (later confirmed by the discovery of the cosmic expansion). Then for 40 years the theory was more or less forgotten, partly because most physicists were turning their attention to the even more radical developments of quantum theory but also because the equations were too complicated to solve except in situations involving special symmetries or very weak gravitational fields (where general relativity is very similar to Newtonian theory). Furthermore, it was not clear that strong gravitational fields would ever arise in the real universe and, even if they did, it seemed unlikely that Einstein's equations could then be solved. So research in relativity became a quiet backwater as mainstream physics swept forward in other directions. Even Einstein lost interest, turning his attention to the search for a unified field theory. This book tells the remarkable story of how the tide changed in 1963, when the 28-year-old New Zealand mathematician Roy Kerr discovered an exact solution of Einstein's equations which represents a rotating black hole, thereby cracking the code of the title. The paper was just a few pages long, it being left for others to fill in the extensive beautiful mathematics which underlay the result, but it ushered in a golden age of relativity and is now one of the most cited works in physics. Coincidentally, Kerr's breakthrough was not the only one in 1963 because Maarten Schmidt also discovered the first quasar, 3C273. By recognizing its redshifted spectrum and hence its huge cosmological distance, he demonstrated that some stupendous source of energy was required. Nowadays, most astrophysicists assume this must involve a supermassive black hole of the kind Kerr discovered, so it was a serendipitous combination of theoretical and observational developments that placed general relativity once more at centre-stage. Both discoveries were announced at the First Texas Symposium of Relativistic Astrophysics in Dallas in December 1963 but met with very different receptions. Schmidt's report generated huge excitement and was the main focus of the meeting. By contrast, Kerr's report was a mere 10-minute presentation - its importance appreciated only by the small group of relativists present, including Achilles Papapetrou, who admonished the audience for giving the talk such a lukewarm reception. Indeed, Kerr nearly didn't speak at all since Roger Penrose had originally been asked to report on his new solution as part of an overview talk. Nevertheless, Kerr's discovery proved to be of equal importance in the burgeoning field of relativistic astrophysics and it soon spawned dozens of other important papers. Indeed, by the time John Wheeler coined the phrase `black hole' in 1967, many of the well-known properties of the Kerr solution - the rotating event horizon, the ring singularity, the inner horizon, the closed timelike curves and the ergosphere - had already been established. The solution was also generalized to the electrically charged case by Ted Newman. Most remarkably, work by Werner Israel, Brandon Carter and Stephen Hawking showed that the Kerr-Newman solution represents the unique end-state of rotating collapsing matter. This means that black holes (unlike other astronomical objects) can be completely described by their mass, angular momentum and charge. This so-called `no hair theorem' explains why Kerr's discovery is so important. Today 15000 quasars are known and all are thought to be powered by Kerr black holes. Indeed, a large fraction of the x-ray background detected by the Chandra satellite is thought to have been generated by such holes, in which case there could 300 million of them in the observable universe. Subrahmanyan Chandrasekhar, after whom the satellite is named, best expressed the situation [1]: `the most shattering experience has been the realization that an exact solution of Einstein's equations of general relativity…provides the absolutely exact representation of untold numbers of black holes that populate the universe'. The account so far will be very familiar to most relativists. However, probably very few know the full story of the events leading up to Kerr's great discovery and that is what this fascinating and informative book provides. It adds three important elements to the usual accounts: it describes the personalities involved, it explains how the solution was found, and it puts the episode in a broader historical context. I will now discuss these elements in turn. Focusing on the personalities is important because science is a very human endeavour - involving passion, excitement, missed opportunity, serendipidity and sometimes tragedy - and this story has all of these elements. The central character is Kerr himself, who provides his own afterword to the book. Surprisingly, he was not originally a relativist at all but a pure mathematician. After his undergraduate studies at the University of Canterbury in Christchurch, he started a PhD in group theory at Cambridge. However, it was during this period that he was introduced to relativity by his friend John Moffatt and then further enthused by an influential seminar on gravitational radiation by Felix Pirani at King's College London. A sequence of postdoctoral positions in the USA followed, culminating in his move to Alfred Schild's Center for Relativity in Austin, Texas, where he wrote his seminal paper. The second strength of this book is that it shows how Kerr's discovery related to other developments in the field. Progress in physics is rarely made in isolation and there is a strong supporting cast in this drama. The key to his breakthrough was the simplification of Einstein's equations entailed in studying what are termed `shear-free' solutions. The first clue came from Ray Sachs, whose studies of asymptotically shear-free bundles of light-rays reduced Einstein's equations to manageable form. Ivor Robinson and Andrzej Trautman then considered bundles which are shear-free everywhere but they were looking for solutions with gravity waves rather than time-independent ones and so missed the great discovery. Kerr learnt about these developments at a 1962 meeting on Gravitation and General Relativity in Warsaw, which clearly played a seminal role in the development of his ideas. But what most excited him was the enthusiastic summary of Vitaly Ginzburg, extolling the virtues of general relativity and emphasizing the need to understand strong gravity effects such as rotation. In any case, he returned to Austin convinced that he had the tools required to solve the problem. At first, he was discouraged when Newman claimed to prove that no shear-free space is possible but fortunately Kerr found a mistake in this work. By using coordinates which incorporated the rotational symmetry of the problem, he was able to find an exact solution in which the metric contains an event horizon and is asymptotically rotating. Since the Warsaw meeting played such a crucial role, it is interesting to recall that Richard Feynman also attended the meeting and described it in rather unflattering terms in a letter to his wife [2]: `I am not getting anything out of the meeting. I am learning nothing. Because there are no experiments, this field is not an active one, so few of the best men are doing work in it. The result is that there are hosts of dopes here and it is not good for my blood pressure…remind me not to come to any more gravity conferences!'. The book does not mention this but Feynman's negativity may have resulted from the fact that he attended the meeting primarily to present his early work on quantum gravity. This did not excite the relativists as much as he had hoped, so this may have generated some antipathy. Nevertheless, his impression is interesting because it reflects the prevailing opinion at the time that relativity had made little progress since the 1930s. Feynman clearly did't recognize the significance of the Pound-Rebka experiment (which had recently measured the slowing down of time in the gravitational field of the Earth) or appreciate that a new band of young relativists were instilling fresh energy into the field, unintimidated by the fear (prevalent at the time) of what Einstein might say about their endeavours. The third strength of this book is that it puts Kerr's discovery in broader historical context. It starts with a useful discussion of the earlier development of ideas in special and general relativity. Most of this is well known but it also includes some points which are rarely described in popular accounts. Of particular interest is Melia's account of the exchanges between Einstein and the mathematician David Hilbert in 1915. He suggests that Hilbert may have submitted a paper containing the correct equations of general relativity five days earlier than Einstein, although this is controversial since Einstein's paper was certainly published first and Hilbert may well have modified his own paper after reading it [3]. It is also good to stress the contribution of Emmy Noether, who first found the connection between symmetries and conservation laws. This is described in a book by Leon Lederman and Chris Hill [4] as `certainly one of the most important mathematical theorems ever proved in guiding the development of modern physics'. Since Kerr was himself a mathematician, one important message of this book (at least implicitly) seems to be the fundamental importance of mathematics in the development of physics. This is very topical in view of the current controversy over whether string theory should be regarded as mathematics or physics. One might question Melia's assertion that the golden age initiated by Kerr ended in the mid-1970s. Certainly the detection of stellar black holes, the discovery of the binary pulse PSR 1913+16, the precise measurement of the slowing down of time in a gravitational field by Gravity Probe A, and the discovery of black hole quantum radiation all came in this period. However, in some ways relativity is still enjoying a golden age: it is just that most research now focuses on numerical relativity, gravitational waves and quantum gravity rather than looking for exact solutions of Einstein's equations. For example, the detection of gravitational waves will surely herald another golden age within the next few years. What is true is that old-fashioned classical relativity has again moved to the side-lines and this raises an interesting point. In the search for a unified theory, either quantum theory or relativity must triumph because they are incompatible. Some people (in particular, the string theorists) feel that quantum theory will eventually triumph, with general relativity just representing a first level of approximation to the final picture. However, others (e.g., Roger Penrose and proponents of loop quantum gravity) feel that general relativity will turn out to be more fundamental. It is too soon to decide which side is correct. There are clearly further codes to break. Finally, what has become of the code-breaker himself? Kerr maintained links with Austin until 1977 when Schild died. By then he had become disillusioned with the aggressive nature of science in America. Nor was the aggression confined to the ivory towers of academia, since he was in Austin in 1966, when a crazed gunman in the university tower shot several people dead, one of whom was Kerr's fellow-relativist Robert Boyer. He returned to the University of Canterbury in 1971, where he headed the Mathematics Department until his retirement in 1993. He remains a colourful character, whose interests go well beyond relativity. Indeed, his first love is now rumoured to be bridge! To an end on a personal note, I've always felt a close affinity with Kerr because his surname is a variant of my own. This has sometimes had amusing consequences. On a trip to China in 1985, I was surprised when one of my talks attracted a huge audience. It later transpired that I had been confused with my more famous near name-sake! References [1] Chandrasekher S 1987 Truth and Beauty: Aesthetics and Motivations in Science (Chicago, IL: University of Chicago Press) [2] Feynman, RP 1988 What Do You Care What Other People Think? (New York, NY: Norton Press) [3] Corry L, Renn J and Stachel J, 1997 Belated decision in the Hilbert--Einstein priority dispute Science278 1270 [4] Lederman L M and Hill C T 2004 Symmetry and the Beautiful Universe (New York, NY: Prometheus Books)

Why natural science needs phenomenological philosophy.

PubMed

Rosen, Steven M

2015-12-01

Through an exploration of theoretical physics, this paper suggests the need for regrounding natural science in phenomenological philosophy. To begin, the philosophical roots of the prevailing scientific paradigm are traced to the thinking of Plato, Descartes, and Newton. The crisis in modern science is then investigated, tracking developments in physics, science's premier discipline. Einsteinian special relativity is interpreted as a response to the threat of discontinuity implied by the Michelson-Morley experiment, a challenge to classical objectivism that Einstein sought to counteract. We see that Einstein's efforts to banish discontinuity ultimately fall into the "black hole" predicted in his general theory of relativity. The unavoidable discontinuity that haunts Einstein's theory is also central to quantum mechanics. Here too the attempt has been made to manage discontinuity, only to have this strategy thwarted in the end by the intractable problem of quantum gravity. The irrepressible discontinuity manifested in the phenomena of modern physics proves to be linked to a merging of subject and object that flies in the face of Cartesian philosophy. To accommodate these radically non-classical phenomena, a new philosophical foundation is called for: phenomenology. Phenomenological philosophy is elaborated through Merleau-Ponty's concept of depth and is then brought into focus for use in theoretical physics via qualitative work with topology and hypercomplex numbers. In the final part of this paper, a detailed summary is offered of the specific application of topological phenomenology to quantum gravity that was systematically articulated in The Self-Evolving Cosmos (Rosen, 2008a). Copyright © 2015. Published by Elsevier Ltd.

Nonextensive kinetic theory and H-theorem in general relativity

NASA Astrophysics Data System (ADS)

Santos, A. P.; Silva, R.; Alcaniz, J. S.; Lima, J. A. S.

2017-11-01

The nonextensive kinetic theory for degenerate quantum gases is discussed in the general relativistic framework. By incorporating nonadditive modifications in the collisional term of the relativistic Boltzmann equation and entropy current, it is shown that Tsallis entropic framework satisfies a H-theorem in the presence of gravitational fields. Consistency with the 2nd law of thermodynamics is obtained only whether the entropic q-parameter lies in the interval q ∈ [ 0 , 2 ] . As occurs in the absence of gravitational fields, it is also proved that the local collisional equilibrium is described by the extended Bose-Einstein (Fermi-Dirac) q-distributions.

General relativity in upper secondary school: Design and evaluation of an online learning environment using the model of educational reconstruction

NASA Astrophysics Data System (ADS)

Kersting, Magdalena; Henriksen, Ellen Karoline; Bøe, Maria Vetleseter; Angell, Carl

2018-06-01

Because of its abstract nature, Albert Einstein's theory of general relativity is rarely present in school physics curricula. Although the educational community has started to investigate ways of bringing general relativity to classrooms, field-tested educational material is rare. Employing the model of educational reconstruction, we present a collaborative online learning environment that was introduced to final year students (18-19 years old) in six Norwegian upper secondary physics classrooms. Design-based research methods guided the development of the learning resources, which were based on a sociocultural view of learning and a historical-philosophical approach to teaching general relativity. To characterize students' learning from and interaction with the learning environment we analyzed focus group interviews and students' oral and written responses to assigned problems and discussion tasks. Our findings show how design choices on different levels can support or hinder understanding of general relativity, leading to the formulation of design principles that help to foster qualitative understanding and encourage collaborative learning. The results indicate that upper secondary students can obtain a qualitative understanding of general relativity when provided with appropriately designed learning resources and sufficient scaffolding of learning through interaction with teacher and peers.

Towards standard testbeds for numerical relativity

NASA Astrophysics Data System (ADS)

Alcubierre, Miguel; Allen, Gabrielle; Bona, Carles; Fiske, David; Goodale, Tom; Guzmán, F. Siddhartha; Hawke, Ian; Hawley, Scott H.; Husa, Sascha; Koppitz, Michael; Lechner, Christiane; Pollney, Denis; Rideout, David; Salgado, Marcelo; Schnetter, Erik; Seidel, Edward; Shinkai, Hisa-aki; Shoemaker, Deirdre; Szilágyi, Béla; Takahashi, Ryoji; Winicour, Jeff

2004-01-01

In recent years, many different numerical evolution schemes for Einstein's equations have been proposed to address stability and accuracy problems that have plagued the numerical relativity community for decades. Some of these approaches have been tested on different spacetimes, and conclusions have been drawn based on these tests. However, differences in results originate from many sources, including not only formulations of the equations, but also gauges, boundary conditions, numerical methods and so on. We propose to build up a suite of standardized testbeds for comparing approaches to the numerical evolution of Einstein's equations that are designed to both probe their strengths and weaknesses and to separate out different effects, and their causes, seen in the results. We discuss general design principles of suitable testbeds, and we present an initial round of simple tests with periodic boundary conditions. This is a pivotal first step towards building a suite of testbeds to serve the numerical relativists and researchers from related fields who wish to assess the capabilities of numerical relativity codes. We present some examples of how these tests can be quite effective in revealing various limitations of different approaches, and illustrating their differences. The tests are presently limited to vacuum spacetimes, can be run on modest computational resources and can be used with many different approaches used in the relativity community.

A search for pre-main sequence stars in the high-latitude molecular clouds. II - A survey of the Einstein database

NASA Technical Reports Server (NTRS)

Caillault, Jean-Pierre; Magnani, Loris

1990-01-01

The preliminary results are reported of a survey of every EINSTEIN image which overlaps any high-latitude molecular cloud in a search for X-ray emitting pre-main sequence stars. This survey, together with complementary KPNO and IRAS data, will allow the determination of how prevalent low mass star formation is in these clouds in general and, particularly, in the translucent molecular clouds.

BOOK REVIEW: Einstein's General Theory of Relativity—with Modern Applications in Cosmology

NASA Astrophysics Data System (ADS)

Barrabès, C.

2008-09-01

The increasing prominence of general relativity in astrophysics and cosmology is reflected in the growing number of texts, particularly at the undergraduate level. A natural attitude before opening a new one is to ask i) what makes this different from those already published? And ii) does it follow the 'physics-first approach' as for instance the book by Hartle where the basic physical concepts are introduced first with as little formalism as possible, or does it follow the more traditional 'math-first approach' for which the mathematical formalism comes first and is then applied to phyics? As announced in the title, a distinctive feature of the book by Gron and Hervik is the space (almost half the book) devoted to cosmology and in particular to some of the most recent developments in this rapidly evolving field. It is also apparent that the authors have chosen, like the majority of current books on general relativity, the 'math-first approach'. The book is divided into six parts, each of them subdivided into chapters with part VI containing a few short technical appendices. The first part of the book briefly presents in chapter I the principles of relativity, Newtonian mechanics and the Newtonian theory of gravity. In chapter II, a short introduction to special relativity is given. It seems at first surprising that the four-dimensional structure of space-time is not more fully exploited so that the reader would gain familiarity early on with notions like 4-velocity, 4-momentum and the stress energy tensor. This is in fact postponed to part II as an illustration of the mathematical formalism. The second part is devoted to those elements of differential geometry needed in this kind of course. The authors' presentation is somewhat similar to that of the books by Misner, Thorne and Wheeler and by Straumann (2nd edition). Vectors and forms are treated separately and the formalism of differential forms is introduced in detail. The various kinds of differentiation on forms and on vectors (exterior covariant and Lie derivatives) are presented, and emphasis is given to the Cartan formalism as it is later systematically used to derive the curvature tensor and for solutions of the Einstein field equations. One also finds the properties of hypersurfaces, such as the intrinsic and extrinsic curvatures and the Gauss Codazzi relations. This makes this part of the book very useful and convenient since those important elements are gathered in one place. However the density of exposition in this part might appear a bit steep to a reader without some previous knowledge of differential geometry. Part III deals with Einstein's field equations, and their applications to gravitational waves and black holes. The field equations are derived from a variational principle, the geometrical part (Einstein tensor) from the Einstein Hilbert action, and the matter part (stress energy tensor) from a generic action integral for matter. Various examples of stress energy tensors and in particular, for fluids, are considered, and several are used later in cosmology (for instance quintessence and Lorentz invariant vacuum energy). A short chapter on the linear approximation and gravitational waves then follows and it is good to see a section on gravito-electromagnetism. This part ends with a chapter devoted to black holes which is perhaps the weakest part of the book as it is quite sketchy. However this is to be expected in a book with an emphasis on cosmology, and such topics are extensively described in other books. The rest of the book (parts IV and V) is essentially concerned with cosmology. The authors give a detailed description of the applications of the Einstein field equations to a universe with various matter contents, and present in a successful way the recent developments in this domain. The first chapter of part IV describes the standard homogeneous and isotropic cosmological model. It is followed by an interesting chapter dealing with universes composed of vacuum energy. There one finds, after the description of the Einstein static universe and the de Sitter solution, sections on inflation, on the Friedman Lemaître model and on models with quintessence and dark energy. This chapter ends with sections on cosmic density perturbations, temperature fluctations in the cosmic microwave background and on the history of our universe. With an additional chapter on anisotropic and homogeneous universes, part IV appears to be a very good and complete introduction to the basic and classical (i.e. non-quantum) elements of cosmology. In part V some advanced tools, such as Lie groups and the Lagrangian and Hamiltonian formalism are introduced and applied to cosmology. Also part V contains a chapter on the extrinsic curvature formalism for surface layers and its application to the recently introduced braneworld models. Finally it is a pleasant surprise to find an introduction to the Kaluza Klein theory as the last chapter of part V. This book by Gron and Hervik certainly has its place in any good library. It covers most of the classical aspects of the theory of general relativity. The authors have made the effort to discuss many observational aspects and to illustrate the different chapters with many problems. One might regret that the authors' style is generally rather terse and not enough space is always reserved for explanation of physical concepts and for motivations of the theory (for instance, why curvature is so fundamental). This book would be most appropriate for graduate students and I will definitely recommend it as a reference textbook as well as a useful complement to other textbooks on general relativity.

Leibniz algebroids, generalized Bismut connections and Einstein-Hilbert actions

NASA Astrophysics Data System (ADS)

Jurčo, Branislav; Vysoký, Jan

2015-11-01

Connection, torsion and curvature are introduced for general (local) Leibniz algebroids. Generalized Bismut connection on TM ⊕ΛpT∗ M is an example leading to a scalar curvature of the form R +H2 for a closed (p + 2) -form H.

Monogamy inequalities for the Einstein-Podolsky-Rosen paradox and quantum steering

NASA Astrophysics Data System (ADS)

Reid, M. D.

2013-12-01

Monogamy inequalities for the way bipartite Einstein-Podolsky-Rosen (EPR) steering can be distributed among N systems are derived. One set of inequalities is based on witnesses with two measurement settings, and may be used to demonstrate correlation of outcomes between two parties, that cannot be shared with more parties. It is shown that the monogamy for steering is directional. Two parties cannot independently demonstrate steering of a third system, using the same two-setting steering witness, but it is possible for one party to steer two independent systems. This result explains the monogamy of two-setting Bell inequality violations and the sensitivity of the continuous variable (CV) EPR criterion to losses on the steering party. We generalize to m settings. A second type of monogamy relation gives the quantitative amount of sharing possible, when the number of parties is less than or equal to m, and takes a form similar to the Coffman-Kundu-Wootters relation for entanglement. The results enable characterization of the tripartite steering for CV Gaussian systems and qubit Greenberger-Horne-Zeilinger and W states.

Strong gravitational lensing: relativity in action

NASA Astrophysics Data System (ADS)

Wambsganss, Joachim

2010-01-01

Deflection of light by gravity was predicted by Einstein's Theory of General Relativity and observationally confirmed in 1919. In the following decades, various aspects of the gravitational lens effect were explored theoretically, among them measuring the Hubble constant from multiple images of a background source, making use of the magnifying effect as a gravitational telescope, or the possibility of a “relativistic eclipse” as a perfect test of GR. Only in 1979, gravitational lensing became an observational science when the first doubly imaged quasar was discovered. Today lensing is a booming part of astrophysics and cosmology. A whole suite of strong lensing phenomena have been investigated: multiple quasars, giant luminous arcs, Einstein rings, quasar microlensing, and galactic microlensing. The most recent lensing application is the detection of extrasolar planets. Lensing has contributed significant new results in areas as different as the cosmological distance scale, mass determination of galaxy clusters, physics of quasars, searches for dark matter in galaxy halos, structure of the Milky Way, stellar atmospheres and exoplanets. A guided tour through some of these applications will illustrate how gravitational lensing has established itself as a very useful universal astrophysical tool.

The mass formula for an exotic BTZ black hole

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Baocheng, E-mail: zhangbc.zhang@yahoo.com

2016-04-15

An exotic Bañados–Teitelboim–Zanelli (BTZ) black hole has an angular momentum larger than its mass in three dimension (3D), which suggests the possibility that cosmic censorship could be violated if angular momentum is extracted by the Penrose process. In this paper, we propose a mass formula for the exotic BTZ black hole and show no violation of weak cosmic censorship in the gedanken process above by understanding properly its mass formula. Unlike the other black holes, the total energy of the exotic BTZ black hole is represented by the angular momentum instead of the mass, which supports a basic point ofmore » view that the same geometry should be determined by the same energy in 3D general relativity whose equation of motion can be given either by normal 3D Einstein gravity or by exotic 3D Einstein gravity. However, only the mass of the exotic black hole is related to the thermodynamics and other forms of energy are “dumb”, which is consistent with the earlier thermodynamic analysis about exotic black holes.« less

The Einstein equations on the 3-brane world

NASA Astrophysics Data System (ADS)

Shiromizu, Tetsuya; Maeda, Kei-Ichi; Sasaki, Misao

2000-07-01

We carefully investigate the gravitational equations of the brane world, in which all the matter forces except gravity are confined on the 3-brane in a 5-dimensional spacetime with Z2 symmetry. We derive the effective gravitational equations on the brane, which reduce to the conventional Einstein equations in the low energy limit. From our general argument we conclude that the first Randall-Sundrum-type theory predicts that the brane with a negative tension is an antigravity world and hence should be excluded from the physical point of view. Their second-type theory where the brane has a positive tension provides the correct signature of gravity. In this latter case, if the bulk spacetime is exactly anti-de Sitter spacetime, generically the matter on the brane is required to be spatially homogeneous because of the Bianchi identities. By allowing deviations from anti-de Sitter spacetime in the bulk, the situation will be relaxed and the Bianchi identities give just the relation between the Weyl tensor and the energy momentum tensor. In the present brane world scenario, the effective Einstein equations cease to be valid during an era when the cosmological constant on the brane is not well defined, such as in the case of the matter dominated by the potential energy of the scalar field.

Higher-order gravity in higher dimensions: geometrical origins of four-dimensional cosmology?

NASA Astrophysics Data System (ADS)

Troisi, Antonio

2017-03-01

Determining the cosmological field equations is still very much debated and led to a wide discussion around different theoretical proposals. A suitable conceptual scheme could be represented by gravity models that naturally generalize Einstein theory like higher-order gravity theories and higher-dimensional ones. Both of these two different approaches allow one to define, at the effective level, Einstein field equations equipped with source-like energy-momentum tensors of geometrical origin. In this paper, the possibility is discussed to develop a five-dimensional fourth-order gravity model whose lower-dimensional reduction could provide an interpretation of cosmological four-dimensional matter-energy components. We describe the basic concepts of the model, the complete field equations formalism and the 5-D to 4-D reduction procedure. Five-dimensional f( R) field equations turn out to be equivalent, on the four-dimensional hypersurfaces orthogonal to the extra coordinate, to an Einstein-like cosmological model with three matter-energy tensors related with higher derivative and higher-dimensional counter-terms. By considering the gravity model with f(R)=f_0R^n the possibility is investigated to obtain five-dimensional power law solutions. The effective four-dimensional picture and the behaviour of the geometrically induced sources are finally outlined in correspondence to simple cases of such higher-dimensional solutions.

Testing Einstein's theory of gravity in a millisecond pulsar triple system

NASA Astrophysics Data System (ADS)

Archibald, Anne

2015-04-01

Einstein's theory of gravity depends on a key postulate, the strong equivalence principle. This principle says, among other things, that all objects fall the same way, even objects with strong self-gravity. Almost every metric theory of gravity other than Einstein's general relativity violates the strong equivalence principle at some level. While the weak equivalence principle--for objects with negligible self-gravity--has been tested in the laboratory, the strong equivalence principle requires astrophysical tests. Lunar laser ranging provides the best current tests by measuring whether the Earth and the Moon fall the same way in the gravitational field of the Sun. These tests are limited by the weak self-gravity of the Earth: the gravitational binding energy (over c2) over the mass is only 4 . 6 ×10-10 . By contrast, for neutron stars this same ratio is expected to be roughly 0 . 1 . Thus the recently-discovered system PSR J0337+17, a hierarchical triple consisting of a millisecond pulsar and two white dwarfs, offers the possibility of a test of the strong equivalence principle that is more sensitive by a factor of 20 to 100 than the best existing test. I will describe our observations of this system and our progress towards such a test.

Scale relativity: from quantum mechanics to chaotic dynamics.

NASA Astrophysics Data System (ADS)

Nottale, L.

Scale relativity is a new approach to the problem of the origin of fundamental scales and of scaling laws in physics, which consists in generalizing Einstein's principle of relativity to the case of scale transformations of resolutions. We recall here how it leads one to the concept of fractal space-time, and to introduce a new complex time derivative operator which allows to recover the Schrödinger equation, then to generalize it. In high energy quantum physics, it leads to the introduction of a Lorentzian renormalization group, in which the Planck length is reinterpreted as a lowest, unpassable scale, invariant under dilatations. These methods are successively applied to two problems: in quantum mechanics, that of the mass spectrum of elementary particles; in chaotic dynamics, that of the distribution of planets in the Solar System.

Einstein@Home Finds a Double Neutron Star

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-12-01

Have you been contributing your computer idle time to the Einstein@Home project? If so, youre partly responsible for the programs recent discovery of a new double-neutron-star system that will be key to learning about general relativity and stellar evolution.The 305-m Arecibo Radio Telescope, built into the landscape at Arecibo, Puerto Rico. [NOAO/AURA/NSF/H. Schweiker/WIYN]The Hunt for PulsarsObserving binary systems containing two neutron stars and in particular, measuring the timing of the pulses when one or both companions is a pulsar can provide highly useful tests of general relativity and binary stellar evolution. Unfortunately, these systems are quite rare: of 2500 known radio pulsars, only 14 of them are in double-neutron-starbinaries.To find more systems like these, we perform large-scale, untargeted radio-pulsar surveys like the ongoing Pulsar-ALFA survey conducted with the enormous 305-m radio telescope at Arecibo Observatory in Puerto Rico. But combing through these data for the signature of a highly accelerated pulsar (the acceleration is a clue that its in a compact binary) is very computationally expensive.PSR J1913+1102s L-band pulse profile, created by phase-aligning and summing all observations. [Adapted from Lazarus et al. 2016]To combat this problem, the Einstein@Home project was developed. Einstein@Home allows anyone to volunteer their personal computers idle time to help run the analysis of survey data in the search for pulsars. In a recent publication led by Patrick Lazarus (Max Planck Institute for Radio Astronomy), the Einstein@Home team announced the discovery of the pulsar PSR J1913+1102 a member of what seems to be a brand new double-neutron-starsystem.An Intriguing DiscoveryLazarus and collaborators followed up on the discovery to obtain timing measurements of the pulsar, which they found to have a spin period of 27.3 ms. They measured PSR J1913+1102 to be in a 4.95-hr, nearly circular (e 0.09) binary orbit with a massive companion that, based on its properties, is most likely another neutron star. The team wasnt able to detect pulsations from the companion, but that could mean that its beam doesnt cross the Earth, or its very faint, or its simply no longer active as a pulsar.Orbital evolution of the six known double-neutron-star systems that will coalesce within a Hubble time, including J1913+1102 (black solid line). They move toward the origin as they lose energy to gravitational waves and approach merger. Shown are current positions (black dots), estimates of the positions when the compact binaries were formed (grey dots), and future evolution. [Lazarus et al. 2016]Lazarus and collaborators use their observations of the system to arguethat PSR J1913+1102 waslikely spun up (recycled) by accretion of matter from its companions progenitor. The companion then exploded in the second supernova of the system, providing a very small kick hence the low eccentricity of the system and resulting in the current double-neutron-starbinary we observe.Lessons from PSR J1913+1102Observations of compact binaries such as this one can reveal a wealth of information. Besides providing clues about how the binary evolved, precise timing measurements (now being made) will also allow powerful tests of general relativity.One of the measurements that may be possible by the end of this year will provide information about the orbital decay of the binary expected to continue for 0.5 Gyr until the system merges due to the emission of gravitational waves.In the meantime, you can bet that Einstein@Home will continue hunting for more systems like PSR J1913+1102 and its companion!CitationP. Lazarus et al 2016 ApJ 831 150. doi:10.3847/0004-637X/831/2/150

'But one must not legalize the mentioned sin': Phenomenological vs. dynamical treatments of rods and clocks in Einstein's thought

NASA Astrophysics Data System (ADS)

Giovanelli, Marco

2014-11-01

This paper offers a historical overview of Einstein's vacillating attitude towards 'phenomenological' and 'dynamical' treatments of rods and clocks in relativity theory. In Einstein's view, a realistic microscopic model of rods and clocks was needed to account for the very existence of measuring devices of identical construction that always measure the same unit of time and the same unit of length. It will be shown that the empirical meaningfulness of both relativity theories depends on what, following Max Born, one might call the 'principle of the physical identity of the units of measure'. In an attempt to justify the validity of such a principle, Einstein was forced by different interlocutors, in particular Hermann Weyl and Wolfgang Pauli, to deal with the genuine epistemological, rather than the physical question of whether a theory should be required to describe the material devices needed for its own verification.

Simple, explicitly time-dependent, and regular solutions of the linearized vacuum Einstein equations in Bondi-Sachs coordinates

NASA Astrophysics Data System (ADS)

Mädler, Thomas

2013-05-01

Perturbations of the linearized vacuum Einstein equations in the Bondi-Sachs formulation of general relativity can be derived from a single master function with spin weight two, which is related to the Weyl scalar Ψ0, and which is determined by a simple wave equation. By utilizing a standard spin representation of tensors on a sphere and two different approaches to solve the master equation, we are able to determine two simple and explicitly time-dependent solutions. Both solutions, of which one is asymptotically flat, comply with the regularity conditions at the vertex of the null cone. For the asymptotically flat solution we calculate the corresponding linearized perturbations, describing all multipoles of spin-2 waves that propagate on a Minkowskian background spacetime. We also analyze the asymptotic behavior of this solution at null infinity using a Penrose compactification and calculate the Weyl scalar Ψ4. Because of its simplicity, the asymptotically flat solution presented here is ideally suited for test bed calculations in the Bondi-Sachs formulation of numerical relativity. It may be considered as a sibling of the Bergmann-Sachs or Teukolsky-Rinne solutions, on spacelike hypersurfaces, for a metric adapted to null hypersurfaces.

The Light-Velocity Postulate: The Essential Difference between the Theories of Lorentz-Poincare and Einstein

ERIC Educational Resources Information Center

Abiko, Seiya

2005-01-01

Einstein, who had already developed the light-quantum theory, knew the inadequacy of Maxwell's theory in the microscopic sphere. Therefore, in writing his paper on special relativity, he had to set up the light-velocity postulate independently of the relativity postulate in order to make the electromagnetic foundation of physics compatible with…

Einstein’s gravity from a polynomial affine model

NASA Astrophysics Data System (ADS)

Castillo-Felisola, Oscar; Skirzewski, Aureliano

2018-03-01

We show that the effective field equations for a recently formulated polynomial affine model of gravity, in the sector of a torsion-free connection, accept general Einstein manifolds—with or without cosmological constant—as solutions. Moreover, the effective field equations are partially those obtained from a gravitational Yang–Mills theory known as Stephenson–Kilmister–Yang theory. Additionally, we find a generalization of a minimally coupled massless scalar field in General Relativity within a ‘minimally’ coupled scalar field in this affine model. Finally, we present a brief (perturbative) analysis of the propagators of the gravitational theory, and count the degrees of freedom. For completeness, we prove that a Birkhoff-like theorem is valid for the analyzed sector.

Visiting the Gödel universe.

PubMed

Grave, Frank; Buser, Michael

2008-01-01

Visualization of general relativity illustrates aspects of Einstein's insights into the curved nature of space and time to the expert as well as the layperson. One of the most interesting models which came up with Einstein's theory was developed by Kurt Gödel in 1949. The Gödel universe is a valid solution of Einstein's field equations, making it a possible physical description of our universe. It offers remarkable features like the existence of an optical horizon beyond which time travel is possible. Although we know that our universe is not a Gödel universe, it is interesting to visualize physical aspects of a world model resulting from a theory which is highly confirmed in scientific history. Standard techniques to adopt an egocentric point of view in a relativistic world model have shortcomings with respect to the time needed to render an image as well as difficulties in applying a direct illumination model. In this paper we want to face both issues to reduce the gap between common visualization standards and relativistic visualization. We will introduce two techniques to speed up recalculation of images by means of preprocessing and lookup tables and to increase image quality through a special optimization applicable to the Gödel universe. The first technique allows the physicist to understand the different effects of general relativity faster and better by generating images from existing datasets interactively. By using the intrinsic symmetries of Gödel's spacetime which are expressed by the Killing vector field, we are able to reduce the necessary calculations to simple cases using the second technique. This even makes it feasible to account for a direct illumination model during the rendering process. Although the presented methods are applied to Gödel's universe, they can also be extended to other manifolds, for example light propagation in moving dielectric media. Therefore, other areas of research can benefit from these generic improvements.

Spatially covariant theories of gravity: disformal transformation, cosmological perturbations and the Einstein frame

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fujita, Tomohiro; Gao, Xian; Yokoyama, Jun'ichi, E-mail: tomofuji@stanford.edu, E-mail: gao@th.phys.titech.ac.jp, E-mail: yokoyama@resceu.s.u-tokyo.ac.jp

We investigate the cosmological background evolution and perturbations in a general class of spatially covariant theories of gravity, which propagates two tensor modes and one scalar mode. We show that the structure of the theory is preserved under the disformal transformation. We also evaluate the primordial spectra for both the gravitational waves and the curvature perturbation, which are invariant under the disformal transformation. Due to the existence of higher spatial derivatives, the quadratic Lagrangian for the tensor modes itself cannot be transformed to the form in the Einstein frame. Nevertheless, there exists a one-parameter family of frames in which themore » spectrum of the gravitational waves takes the standard form in the Einstein frame.« less

From Newton to Einstein.

ERIC Educational Resources Information Center

Ryder, L. H.

1987-01-01

Discusses the history of scientific thought in terms of the theories of inertia and absolute space, relativity and gravitation. Describes how Sir Isaac Newton used the work of earlier scholars in his theories and how Albert Einstein used Newton's theories in his. (CW)

Multiple Intelligences and the Artistic Imagination: A Case Study of Einstein and Picasso.

ERIC Educational Resources Information Center

Newbold, Clair T.

1999-01-01

Argues that Albert Einstein and Pablo Picasso possessed similar artistic thought processes, maintaining that their influential discoveries (relativity theory and cubist painting), which launched 20th-century modernism, were amazingly similar in concept. (SR)

An instability of the standard model of cosmology creates the anomalous acceleration without dark energy

NASA Astrophysics Data System (ADS)

Smoller, Joel; Temple, Blake; Vogler, Zeke

2017-11-01

We identify the condition for smoothness at the centre of spherically symmetric solutions of Einstein's original equations without the cosmological constant or dark energy. We use this to derive a universal phase portrait which describes general, smooth, spherically symmetric solutions near the centre of symmetry when the pressure p=0. In this phase portrait, the critical k=0 Friedmann space-time appears as a saddle rest point which is unstable to spherical perturbations. This raises the question as to whether the Friedmann space-time is observable by redshift versus luminosity measurements looking outwards from any point. The unstable manifold of the saddle rest point corresponding to Friedmann describes the evolution of local uniformly expanding space-times whose accelerations closely mimic the effects of dark energy. A unique simple wave perturbation from the radiation epoch is shown to trigger the instability, match the accelerations of dark energy up to second order and distinguish the theory from dark energy at third order. In this sense, anomalous accelerations are not only consistent with Einstein's original theory of general relativity, but are a prediction of it without the cosmological constant or dark energy.

An instability of the standard model of cosmology creates the anomalous acceleration without dark energy.

PubMed

Smoller, Joel; Temple, Blake; Vogler, Zeke

2017-11-01

We identify the condition for smoothness at the centre of spherically symmetric solutions of Einstein's original equations without the cosmological constant or dark energy. We use this to derive a universal phase portrait which describes general, smooth, spherically symmetric solutions near the centre of symmetry when the pressure p =0. In this phase portrait, the critical k =0 Friedmann space-time appears as a saddle rest point which is unstable to spherical perturbations. This raises the question as to whether the Friedmann space-time is observable by redshift versus luminosity measurements looking outwards from any point. The unstable manifold of the saddle rest point corresponding to Friedmann describes the evolution of local uniformly expanding space-times whose accelerations closely mimic the effects of dark energy. A unique simple wave perturbation from the radiation epoch is shown to trigger the instability, match the accelerations of dark energy up to second order and distinguish the theory from dark energy at third order. In this sense, anomalous accelerations are not only consistent with Einstein's original theory of general relativity, but are a prediction of it without the cosmological constant or dark energy.

Revamping Newtonian Gravity

NASA Astrophysics Data System (ADS)

Eckhardt, Donald H.; Garrido Pestaña, José Luis

2014-06-01

The nineteenth century's quest for the missing matter (Vulcan) ended with the publication of Einstein's General Theory of Relativity. We contend that the current quest for the missing matter is parallel in its perseverance and in its ultimate futility. After setting the search for dark matter in its historic perspective, we critique extant dark matter models and offer alternative explanations -- derived from a Lorentz-invariant Lagrangian -- that will, at the very least, sow seeds of doubt about the existence of dark matter.

Black Holes Collide

NASA Image and Video Library

2017-12-08

When two black holes collide, they release massive amounts of energy in the form of gravitational waves that last a fraction of a second and can be "heard" throughout the universe - if you have the right instruments. Today we learned that the #LIGO project heard the telltale chirp of black holes colliding, fulfilling Einstein's General Theory of Relativity. NASA's LISA mission will look for direct evidence of gravitational waves. go.nasa.gov/23ZbqoE This video illustrates what that collision might look like.

Internal rotation of the sun

NASA Technical Reports Server (NTRS)

Duvall, T. L., Jr.; Dziembowski, W. A.; Goode, P. R.; Gough, D. O.; Harvey, J. W.; Leibacher, J. W.

1984-01-01

The frequency difference between prograde and retrograde sectoral solar oscillations is analyzed to determine the rotation rate of the solar interior, assuming no latitudinal dependence. Much of the solar interior rotates slightly less rapidly than the surface, while the innermost part apparently rotates more rapidly. The resulting solar gravitational quadrupole moment is J2 = (1.7 + or - 0.4) x 10 to the -7th and provides a negligible contribution to current planetary tests of Einstein's theory of general relativity.

(abstract) Spacecraft Doppler Tracking with the Deep Space Network in the Search for Gravitational Waves

NASA Technical Reports Server (NTRS)

Asmar, Sami; Renzetti, Nicholas

1994-01-01

The Deep Space Network generates accurate radio science data observables for investigators who use radio links between spacecraft and the Earth to examine small changes in the phase and/or amplitude of the signal to study a wide variety of structures and phenomena in space. Several such studies are directed at aspects of the theory of general relativity such as gravitational redshift and gravitational waves. A gravitational wave is a propagating, polarized gravitational field, a ripple in the curvature of space-time. In Einstein's theory of general relativity, the waves are propagating solutions of the Einstein field equations. Their amplitudes are dimensionless strain amplitudes that change the fractional difference in distance between test masses and the rates at which separated clocks keep time. Predicted by all relativistic theories of gravity, they are extremely weak (the ratio of gravitational forces to electrical forces is about 10(sup -40)) and are generated at detectable levels only by astrophysical sources - very massive sources under violent dynamical conditions. The waves have never been detected but searches in the low-frequency band using Doppler tracking of many spacecraft have been conducted and others are being planned. Upper limits have been placed on the gravitational wave strength with the best sensitivities to date are for periodic waves being 7 x 10(sup -15).

New perspectives on an old problem: The bending of light in Yang-Mills gravity

NASA Astrophysics Data System (ADS)

Cottrell, Kazuo Ota; Hsu, Jong-Ping

Yang-Mills gravity with electromagnetism predicts, in the geometric optics limit, a value for the deflection of light by the sun which agrees closely with the reanalysis of Eddington's 1919 optical measurements done in 1979. Einstein's General Theory of Relativity, on the other hand, agrees very closely with measurements of the deflection of electromagnetic waves made in the range of radio frequencies. Since both General Relativity and Yang-Mills gravity with electromagnetism in the geometric optics limit make predictions for the optical region which fall within experimental uncertainty, it becomes important to consider the possibility of the existence of a frequency dependence in the measurement results for the deflection of light, in order to determine which theory more closely describes nature...

The confrontation between general relativity and experiment

NASA Technical Reports Server (NTRS)

Will, C. M.

1980-01-01

Experiments that test the foundations of gravitation theory in terms of the Einstein equivalence principle are discussed along with solar system tests of general relativity at the post-Newtonian level. These include classical (light-deflection, time delay and perihelion shift) tests as well as tests of the strong equivalence principle. The binary pulsar is discussed as an extra-solar-system gravitational testing ground, and attention is given to the multipolarity of the waves and the amount of radiation damping. The mass function, periastron shift, redshift-Doppler parameter and rate of change of the orbit period (Pb) of the binary pulsar are also considered, and it is suggested that the measurement of Pb represents the first observation of the effects of gravitational radiation.

Merging Black Holes

NASA Technical Reports Server (NTRS)

Centrella, Joan

2012-01-01

The final merger of two black holes is expected to be the strongest source of gravitational waves for both ground-based detectors such as LIGO and VIRGO, as well as future. space-based detectors. Since the merger takes place in the regime of strong dynamical gravity, computing the resulting gravitational waveforms requires solving the full Einstein equations of general relativity on a computer. For many years, numerical codes designed to simulate black hole mergers were plagued by a host of instabilities. However, recent breakthroughs have conquered these instabilities and opened up this field dramatically. This talk will focus on.the resulting 'gold rush' of new results that is revealing the dynamics and waveforms of binary black hole mergers, and their applications in gravitational wave detection, testing general relativity, and astrophysics

Merging Black Holes

NASA Technical Reports Server (NTRS)

Centrella, Joan

2010-01-01

The final merger of two black holes is expected to be the strongest source of gravitational waves for both ground-based detectors such as LIGO and VIRGO, as well as the space-based LISA. Since the merger takes place in the regime of strong dynamical gravity, computing the resulting gravitational waveforms requires solving the full Einstein equations of general relativity on a computer. For many years, numerical codes designed to simulate black hole mergers were plagued by a host of instabilities. However, recent breakthroughs have conquered these instabilities and opened up this field dramatically. This talk will focus on the resulting gold rush of new results that are revealing the dynamics and waveforms of binary black hole mergers, and their applications in gravitational wove detection, testing general relativity, and astrophysics.

Merging Black Holes

NASA Technical Reports Server (NTRS)

Centrella, Joan

2010-01-01

The final merger of two black holes is expected to be the strongest source of gravitational waves for both ground-based detectors such as LIGO and VIRGO, as well as the space-based LISA. Since the merger takes place in the regime of strong dynamical gravity, computing the resulting gravitational waveforms requires solving the full Einstein equations of general relativity on a computer. For many years, numerical codes designed to simulate black hole mergers were plagued by a host of instabilities. However, recent breakthroughs have conquered these instabilities and opened up this field dramatically. This talk will focus on the resulting gold rush of new results that are revealing the dynamics and waveforms of binary black hole mergers, and their applications in gravitational wave detection, testing general relativity, and astrophysics.

Hardware development for Gravity Probe-B

NASA Technical Reports Server (NTRS)

Bardas, D.; Cheung, W. S.; Gill, D.; Hacker, R.; Keiser, G. M.

1986-01-01

Gravity Probe-B (GP-B), also known as the Stanford Relativity Gyroscope Experiment, will test two fundamental predictions of Einstein's General Theory of Relativity by precise measurement of the precessions of nearly perfect gyroscopes in earth orbit. This endeavor embodies state-of-the-art technologies in many fields, including gyroscope fabrication and readout, cryogenics, superconductivity, magnetic shielding, precision optics and alignment methods, and satellite control systems. These technologies are necessary to enable measurement of the predicted precession rates to the milliarcsecond/year level, and to reduce to 'near zero' all non-General Relativistic torques on the gyroscopes. This paper provides a brief overview of the experiment followed by descriptions of several specific hardware items with highlights on progress to date and plans for future development and tests.

Nonlinear Schrödinger equations for Bose-Einstein condensates

NASA Astrophysics Data System (ADS)

Galati, Luigi; Zheng, Shijun

2013-10-01

The Gross-Pitaevskii equation, or more generally the nonlinear Schrödinger equation, models the Bose-Einstein condensates in a macroscopic gaseous superfluid wave-matter state in ultra-cold temperature. We provide analytical study of the NLS with L2 initial data in order to understand propagation of the defocusing and focusing waves for the BEC mechanism in the presence of electromagnetic fields. Numerical simulations are performed for the two-dimensional GPE with anisotropic quadratic potentials.

Transport properties and Stokes-Einstein relation in Al-rich liquid alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jakse, N.; Pasturel, A.

We use ab initio molecular dynamics simulations to study the transport properties and the validity of the Stokes-Einstein relation in Al-rich liquid alloys with Ni, Cu, and Zn as alloying elements. First, we show that the composition and temperature dependence of their transport properties present different behaviors, which can be related to their local structural ordering. Then, we evidence that the competition between the local icosahedral ordering and the local chemical ordering may cause the breakdown of the Stokes–Einstein relation even in the liquid phase. We demonstrate that this breakdown can be captured by entropy-scaling relationships developed by Rosenfeld andmore » using the two-body excess entropy. Our findings provide a unique framework to study the relation between structure, thermodynamics, and dynamics in metallic melts and pave the way towards the explanation of various complex transport properties in metallic melts.« less

Transport properties and Stokes-Einstein relation in Al-rich liquid alloys

NASA Astrophysics Data System (ADS)

Jakse, N.; Pasturel, A.

2016-06-01

We use ab initio molecular dynamics simulations to study the transport properties and the validity of the Stokes-Einstein relation in Al-rich liquid alloys with Ni, Cu, and Zn as alloying elements. First, we show that the composition and temperature dependence of their transport properties present different behaviors, which can be related to their local structural ordering. Then, we evidence that the competition between the local icosahedral ordering and the local chemical ordering may cause the breakdown of the Stokes-Einstein relation even in the liquid phase. We demonstrate that this breakdown can be captured by entropy-scaling relationships developed by Rosenfeld and using the two-body excess entropy. Our findings provide a unique framework to study the relation between structure, thermodynamics, and dynamics in metallic melts and pave the way towards the explanation of various complex transport properties in metallic melts.

Stokes-Einstein relation and excess entropy in Al-rich Al-Cu melts

NASA Astrophysics Data System (ADS)

Pasturel, A.; Jakse, N.

2016-07-01

We investigate the conditions for the validity of the Stokes-Einstein relation that connects diffusivity to viscosity in melts using entropy-scaling relationships developed by Rosenfeld. Employing ab initio molecular dynamics simulations to determine transport and structural properties of liquid Al1-xCux alloys (with composition x ≤ 0.4), we first show that reduced self-diffusion coefficients and viscosities, according to Rosenfeld's formulation, scale with the two-body approximation of the excess entropy except the reduced viscosity for x = 0.4. Then, we use our findings to evidence that the Stokes-Einstein relation using effective atomic radii is not valid in these alloys while its validity can be related to the temperature dependence of the partial pair-excess entropies of both components. Finally, we derive a relation between the ratio of the self-diffusivities of the components and the ratio of their pair excess entropies.

The reception of relativity in China.

PubMed

Hu, Danian

2007-09-01

Having introduced the theory of relativity from Japan, the Chinese quickly and enthusiastically embraced it during the May Fourth Movement, virtually without controversy. This unique passion for and openness to relativity, which helped advance the study of theoretical physics in China in the 1930s, was gradually replaced by imported Soviet criticism after 1949. During the Cultural Revolution, radical Chinese ideologues sponsored organized campaigns against Einstein and relativity, inflicting serious damage on Chinese science and scientific education. China's economic reforms in the late 1970s empowered scientists and presented them with the opportunity to rehabilitate Einstein and call for social democracy. Einstein has since become the symbol in China of the unity of science and democracy, the two eminent objectives of the May Fourth Movement that remain to be achieved in full. Using the reception of relativity as a case study, the essay also discusses issues involving the historical study of modern Chinese science.

A Generalization of the Einstein-Maxwell Equations

NASA Astrophysics Data System (ADS)

Cotton, Fredrick

2016-03-01

The proposed modifications of the Einstein-Maxwell equations include: (1) the addition of a scalar term to the electromagnetic side of the equation rather than to the gravitational side, (2) the introduction of a 4-dimensional, nonlinear electromagnetic constitutive tensor and (3) the addition of curvature terms arising from the non-metric components of a general symmetric connection. The scalar term is defined by the condition that a spherically symmetric particle be force-free and mathematically well-behaved everywhere. The constitutive tensor introduces two auxiliary fields which describe the particle structure. The additional curvature terms couple both to particle solutions and to electromagnetic and gravitational wave solutions. http://sites.google.com/site/fwcotton/em-30.pdf

Time travel, Clock Puzzles and Their Experimental Tests

NASA Astrophysics Data System (ADS)

Ciufolini, Ignazio

2013-09-01

Is time travel possible? What is Einstein's theory of relativity mathematically predicting in that regard? Is time travel related to the so-called clock `paradoxes' of relativity and if so how? Is there any accurate experimental evidence of the phenomena regarding the different flow of time predicted by General Relativity and is there any possible application of the temporal phenomena predicted by relativity to our everyday life? Which temporal phenomena are predicted in the vicinities of a rotating body and of a mass-energy current, and do we have any experimental test of the occurrence of these phenomena near a rotating body? In this paper, we address and answer some of these questions.

H + O3 Fourier-transform infrared emission and laser absorption studies of OH(X2Pi) radical - An experimental dipole moment function and state-to-state Einstein A coefficients

NASA Technical Reports Server (NTRS)

Nelson, David D., Jr.; Schiffman, Aram; Nesbitt, David J.; Orlando, John J.; Burkholder, James B.

1990-01-01

FTIR emission/absorption spectroscopy is used to measure the relative intensities of 88 pairs of rovibrational transitions of OH(X2Pi) distributed over 16 vibrational bands. The experimental technique used to obtain the Einstein A ratios is discussed. The dipole moment function which follows from the intensity ratios along with Einstein A coefficients calculated from mu(r) is presented.

Two characteristic temperatures for a Bose-Einstein condensate of a finite number of particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Idziaszek, Z.; Institut fuer Theoretische Physik, Universitaet Hannover, D-30167 Hannover,; Rzazewski, K.

2003-09-01

We consider two characteristic temperatures for a Bose-Einstein condensate, which are related to certain properties of the condensate statistics. We calculate them for an ideal gas confined in power-law traps and show that they approach the critical temperature in the limit of large number of particles. The considered characteristic temperatures can be useful in the studies of Bose-Einstein condensates of a finite number of atoms indicating the point of a phase transition.

Numerical relativity in spherical coordinates with the Einstein Toolkit

NASA Astrophysics Data System (ADS)

Mewes, Vassilios; Zlochower, Yosef; Campanelli, Manuela; Ruchlin, Ian; Etienne, Zachariah B.; Baumgarte, Thomas W.

2018-04-01

Numerical relativity codes that do not make assumptions on spatial symmetries most commonly adopt Cartesian coordinates. While these coordinates have many attractive features, spherical coordinates are much better suited to take advantage of approximate symmetries in a number of astrophysical objects, including single stars, black holes, and accretion disks. While the appearance of coordinate singularities often spoils numerical relativity simulations in spherical coordinates, especially in the absence of any symmetry assumptions, it has recently been demonstrated that these problems can be avoided if the coordinate singularities are handled analytically. This is possible with the help of a reference-metric version of the Baumgarte-Shapiro-Shibata-Nakamura formulation together with a proper rescaling of tensorial quantities. In this paper we report on an implementation of this formalism in the Einstein Toolkit. We adapt the Einstein Toolkit infrastructure, originally designed for Cartesian coordinates, to handle spherical coordinates, by providing appropriate boundary conditions at both inner and outer boundaries. We perform numerical simulations for a disturbed Kerr black hole, extract the gravitational wave signal, and demonstrate that the noise in these signals is orders of magnitude smaller when computed on spherical grids rather than Cartesian grids. With the public release of our new Einstein Toolkit thorns, our methods for numerical relativity in spherical coordinates will become available to the entire numerical relativity community.

Compliance of the Stokes-Einstein model and breakdown of the Stokes-Einstein-Debye model for a urea-based supramolecular polymer of high viscosity.

PubMed

Świergiel, Jolanta; Bouteiller, Laurent; Jadżyn, Jan

2014-11-14

Impedance spectroscopy was used for the study of the static and dynamic behavior of the electrical conductivity of a hydrogen-bonded supramolecular polymer of high viscosity. The experimental data are discussed in the frame of the Stokes-Einstein and Stokes-Einstein-Debye models. It was found that the translational movement of the ions is due to normal Brownian diffusion, which was revealed by a fulfillment of Ohm's law by the electric current and a strictly exponential decay of the current after removing the electric stimulus. The dependence of the dc conductivity on the viscosity of the medium fulfills the Stokes-Einstein model quite well. An extension of the model, by including in it the conductivity relaxation time, is proposed in this paper. A breakdown of the Stokes-Einstein-Debye model is revealed by the relations of the dipolar relaxation time to the viscosity and to the dc ionic conductivity. The importance of the C=O···H-N hydrogen bonds in that breakdown is discussed.

On the Correlations between the Particles in the EPR-Paradoxon

NASA Astrophysics Data System (ADS)

Treder, H.-J.

The Einstein-Podolsky-Rosen gedanken-experiment does not imply non-local interactions or an action-at-a-distance.Contrary, the EPR proves the measurements at one particle does not have influences at canonical variables of the other particles if the quantum-mechanical commutation relations are true.But, the EPR implices correlations between the particles which come in by subjective knowledge. These correlations are a priori informations about the relative motion or, complementarily, about the motion of the center of mass. The impression of an action-at-a-distance is produced by the use of usual particle coordinates in the EPR-arrangements.The discussion of the Einstein-Podolsky-Rosen gedanken-experiment (EPR) has been going on over fifty years. EINSTEIN, PODOLSKY, and ROSEN formulated their famous paradox in 1935, and in the discussion between N. BOHR (1935, 1949) and A. EINSTEIN (1936, 1948); A. EINSTEIN (1948) made his point that the EPR implied an action-at-a-distance for quantum-mechanical particles (without obvious classical interactions). His argument is the starting point for the recent discussion about EPR and causality (see A. Aspect, 1981).Translated AbstractÜber die Korrelationen zwischen den Partikeln beim EPR-ParadoxonDas Gedankenexperiment von EINSTEIN, PODOLSKY und ROSEN über die anscheinend paradoxen Beziehungen zwischen beliebig weit entfernten Partikeln gemäß der quantenmechanischen Theorie der Messungen führt tatsächlich nicht auf nichtlokale Wechselwirkungen.Das Einstein-Podolsky-Rosen-Paradoxon zeigt vielmehr, daß die Messung an einem Teilchen keinerlei Einfluß auf die Meßwerte an anderen Partikeln hat, wenn die quantenmechanischen Vertauschungsregeln erfüllt sind.Dagegen weist das Einstein-Podolsky-Rosensche Gedankenexperiment Korrelationen zwischen den Teilchen auf, die die Folge einer a-priori-Kenntnis über die Werte von Hamilton-Jacobischen Zwei-Partikeln-Koordinaten von nicht-wechselwirkenden Teilchen sind.

Bose–Einstein condensation temperature of finite systems

NASA Astrophysics Data System (ADS)

Xie, Mi

2018-05-01

In studies of the Bose–Einstein condensation of ideal gases in finite systems, the divergence problem usually arises in the equation of state. In this paper, we present a technique based on the heat kernel expansion and zeta function regularization to solve the divergence problem, and obtain the analytical expression of the Bose–Einstein condensation temperature for general finite systems. The result is represented by the heat kernel coefficients, where the asymptotic energy spectrum of the system is used. Besides the general case, for systems with exact spectra, e.g. ideal gases in an infinite slab or in a three-sphere, the sums of the spectra can be obtained exactly and the calculation of corrections to the critical temperatures is more direct. For a system confined in a bounded potential, the form of the heat kernel is different from the usual heat kernel expansion. We show that as long as the asymptotic form of the global heat kernel can be found, our method works. For Bose gases confined in three- and two-dimensional isotropic harmonic potentials, we obtain the higher-order corrections to the usual results of the critical temperatures. Our method can also be applied to the problem of generalized condensation, and we give the correction of the boundary on the second critical temperature in a highly anisotropic slab.

Implementation of the Automated Numerical Model Performance Metrics System

DTIC Science & Technology

2011-09-26

question. As of this writing, the DSRC IBM AIX machines DaVinci and Pascal, and the Cray XT Einstein all use the PBS batch queuing system for...3.3). 12 Appendix A – General Automation System This system provides general purpose tools and a general way to automatically run

Inhomogeneous generalization of some Bianchi models

NASA Astrophysics Data System (ADS)

Carmeli, M.; Charach, Ch.

1980-02-01

Vacuum Bianchi models which can be transformed to the Einstein-Rosen metric are considered. The models are used in order to construct new inhomogeneous universes, which are generalizations of Bianchi cosmologies of types III, V and VIh. Recent generalizations of these Bianchi models, considered by Wainwright et al., are also discussed.

Hidden symmetries in Sasaki-Einstein geometries

NASA Astrophysics Data System (ADS)

Slesar, V.; Visinescu, M.; Vîlcu, G. E.

2017-07-01

We describe a method for constructing Killing-Yano tensors on Sasaki spaces using their geometrical properties, without the need of solving intricate generalized Killing equations. We obtain the Killing-Yano tensors on toric Sasaki-Einstein spaces using the fact that the metric cones of these spaces are Calabi-Yau manifolds which in turn are described in terms of toric data. We extend the search of Killing-Yano tensors on mixed 3-Sasakian manifolds. We illustrate the method by explicit construction of Killing forms on some spaces of current interest.

Vector and axial-vector decomposition of Einstein's gravitational action

NASA Astrophysics Data System (ADS)

Soh, Kwang S.

1991-08-01

Vector and axial-vector gravitational fields are introduced to express the Einstein action in the manner of electromagnetism. Their conformal scaling properties are examined, and the resemblance between the general coordinate and electromagnetic gauge transformation is elucidated. The chiral formulation of the gravitational action is constructed. I am deeply grateful to Professor S. Hawking, and Professor G. Lloyd for warm hospitality at DAMTP, and Darwin College, University of Cambridge, respectively. I also appreciate much help received from Dr. Q.-H. Park.

Connecting Numerical Relativity and Data Analysis of Gravitational Wave Detectors

NASA Astrophysics Data System (ADS)

Shoemaker, Deirdre; Jani, Karan; London, Lionel; Pekowsky, Larne

Gravitational waves deliver information in exquisite detail about astrophysical phenomena, among them the collision of two black holes, a system completely invisible to the eyes of electromagnetic telescopes. Models that predict gravitational wave signals from likely sources are crucial for the success of this endeavor. Modeling binary black hole sources of gravitational radiation requires solving the Einstein equations of General Relativity using powerful computer hardware and sophisticated numerical algorithms. This proceeding presents where we are in understanding ground-based gravitational waves resulting from the merger of black holes and the implications of these sources for the advent of gravitational-wave astronomy.

Relativistic Newtonian Dynamics under a central force

NASA Astrophysics Data System (ADS)

Friedman, Yaakov

2016-10-01

Planck's formula and General Relativity indicate that potential energy influences spacetime. Using Einstein's Equivalence Principle and an extension of his Clock Hypothesis, an explicit description of this influence is derived. We present a new relativity model by incorporating the influence of the potential energy on spacetime in Newton's dynamics for motion under a central force. This model extends the model used by Friedman and Steiner (EPL, 113 (2016) 39001) to obtain the exact precession of Mercury without curving spacetime. We also present a solution of this model for a hydrogen-like atom, which explains the reason for a probabilistic description.

Universal Themes of Bose-Einstein Condensation

NASA Astrophysics Data System (ADS)

Proukakis, Nick P.; Snoke, David W.; Littlewood, Peter B.

2017-04-01

Foreword; List of contributors; Preface; Part I. Introduction: 1. Universality and Bose-Einstein condensation: perspectives on recent work D. W. Snoke, N. P. Proukakis, T. Giamarchi and P. B. Littlewood; 2. A history of Bose-Einstein condensation of atomic hydrogen T. Greytak and D. Kleppner; 3. Twenty years of atomic quantum gases: 1995-2015 W. Ketterle; 4. Introduction to polariton condensation P. B. Littlewood and A. Edelman; Part II. General Topics: Editorial notes; 5. The question of spontaneous symmetry breaking in condensates D. W. Snoke and A. J. Daley; 6. Effects of interactions on Bose-Einstein condensation R. P. Smith; 7. Formation of Bose-Einstein condensates M. J. Davis, T. M. Wright, T. Gasenzer, S. A. Gardiner and N. P. Proukakis; 8. Quenches, relaxation and pre-thermalization in an isolated quantum system T. Langen and J. Schmiedmayer; 9. Ultracold gases with intrinsic scale invariance C. Chin; 10. Berezinskii-Kosterlitz-Thouless phase of a driven-dissipative condensate N. Y. Kim, W. H. Nitsche and Y. Yamamoto; 11. Superfluidity and phase correlations of driven dissipative condensates J. Keeling, L. M. Sieberer, E. Altman, L. Chen, S. Diehl and J. Toner; 12. BEC to BCS crossover from superconductors to polaritons A. Edelman and P. B. Littlewood; Part III. Condensates in Atomic Physics: Editorial notes; 13. Probing and controlling strongly correlated quantum many-body systems using ultracold quantum gases I. Bloch; 14. Preparing and probing chern bands with cold atoms N. Goldman, N. R. Cooper and J. Dalibard; 15. Bose-Einstein condensates in artificial gauge fields L. J. LeBlanc and I. B. Spielman; 16. Second sound in ultracold atomic gases L. Pitaevskii and S. Stringari; 17. Quantum turbulence in atomic Bose-Einstein condensates N. G. Parker, A. J. Allen, C. F. Barenghi and N. P. Proukakis; 18. Spinor-dipolar aspects of Bose-Einstein condensation M. Ueda; Part IV. Condensates in Condensed Matter Physics: Editorial notes; 19. Bose-Einstein condensation of photons and grand-canonical condensate fluctuations J. Klaers and M. Weitz; 20. Laser operation and Bose-Einstein condensation: analogies and differences A. Chiocchetta, A. Gambassi and I. Carusotto; 21. Vortices in resonant polariton condensates in semiconductor microcavities D. N. Krizhanovskii, K. Guda, M. Sich, M. S. Skolnick, L. Dominici and D. Sanvitto; 22. Optical control of polariton condensates G. Christmann, P. G. Savvidis and J. J. Baumberg; 23. Disorder, synchronization and phase-locking in non-equilibrium Bose-Einstein condensates P. R. Eastham and B. Rosenow; 24. Collective topological excitations in 1D polariton quantum fluids H. Terças, D. D. Solnyshkov and G. Malpuech; 25. Microscopic theory of Bose-Einstein condensation of magnons at room temperature H. Salman, N. G. Berloff and S. O. Demokritov; 26. Spintronics and magnon Bose-Einstein condensation R. A. Duine, A. Brataas, S. A. Bender and Y. Tserkovnyak; 27. Spin-superfluidity and spin-current mediated non-local transport H. Chen and A. H. MacDonald; 28. Bose-Einstein condensation in quantum magnets C. Kollath, T. Giamarchi and C. Rüegg; Part V. Condensates in Astrophysics and Cosmology: Editorial notes; 29. Bose-Einstein condensates in neutron stars C. J. Pethick, T. Schäfer and A. Schwenk; 30. A simulated cosmological metric: the superfluid 3He condensate G. R. Pickett; 31. Cosmic axion Bose-Einstein condensation N. Banik and P. Sikivie; 32. Graviton BECs: a new approach to quantum gravity G. Dvali and C. Gomez; Universal Bose-Einstein condensation workshop; Index.

Holographic butterfly velocities in brane geometry and Einstein-Gauss-Bonnet gravity with matters

NASA Astrophysics Data System (ADS)

Huang, Wung-Hong

2018-03-01

In the first part of the paper we generalize the butterfly velocity formula to anisotropic spacetime. We apply the formula to evaluate the butterfly velocities in M-branes, D-branes, and strings backgrounds. We show that the butterfly velocities in M2-branes, M5-branes and the intersection M 2 ⊥ M 5 equal to those in fundamental strings, D4-branes and the intersection F 1 ⊥ D 4 backgrounds, respectively. These observations lead us to conjecture that the butterfly velocity is generally invariant under a double-dimensional reduction. In the second part of the paper, we study the butterfly velocity for Einstein-Gauss-Bonnet gravity with arbitrary matter fields. A general formula is obtained. We use this formula to compute the butterfly velocities in different backgrounds and discuss the associated properties.

Black-Hole Solutions to Einstein's Equations in the Presence of Matter and Modifications of Gravitation in Extra Dimensions

NASA Astrophysics Data System (ADS)

Goutéraux, B.

2010-11-01

In this thesis, we wish to examine the black-hole solutions of modified gravity theories inspired by String Theory or Cosmology. Namely, these modifications will take the guise of additional gauge and scalar fields for the so-called Einstein-Maxwell-Dilaton theories with an exponential Liouville potential; and of extra spatial dimensions for Einstein-Gauss-Bonnet theories. The black-hole solutions of EMD theories as well as their integrability are reviewed. One of the main results is that a master equation is obtained in the case of planar horizon topology, which allows to completely integrate the problem for s special relationship between the couplings. We also classify existing solutions. We move on to the study of Gauss-Bonnet black holes, focusing on the six-dimensional case. It is found that the Gauss-Bonnet coupling exposes the Weyl tensor of the horizon to the dynamics, severely restricting the Einstein spaces admissible and effectively lifting some of the degeneracy on the horizon topology. We then turn to the study of the thermodynamic properties of black holes, in General Relativity as well as in EMD theories. For the latter, phase transitions may be found in the canonical ensemble, which resemble the phase transitions for Reissner-Nordström black holes. Generically, we find that the thermodynamic properties (stability, order of phase transitions) depend crucially on the values of the EMD coupling constants. Finally, we interpret our planar EMD solutions holographically as Infra-Red geometries through the AdS/CFT correspondence, taking into account various validity constraints. We also compute AC and DC conductivities as applications to Condensed Matter Systems, and find some properties characteristic of strange metal behaviour.

Construction of nonsingular pre-big-bang and ekpyrotic cosmologies and the resulting density perturbations

NASA Astrophysics Data System (ADS)

Tsujikawa, Shinji; Brandenberger, Robert; Finelli, Fabio

2002-10-01

We consider the construction of nonsingular pre-big-bang and ekpyrotic type cosmological models realized by the addition to the action of specific higher-order terms stemming from quantum corrections. We study models involving general relativity coupled to a single scalar field with a potential motivated by the ekpyrotic scenario. We find that the inclusion of the string loop and quantum correction terms in the string frame makes it possible to obtain solutions of the variational equations which are nonsingular and bouncing in the Einstein frame, even when a negative exponential potential is present, as is the case in the ekpyrotic scenario. This allows us to discuss the evolution of cosmological perturbations without the need to invoke matching conditions between two Einstein universes, one representing the contracting branch, the second the expanding branch. We analyze the spectra of perturbations produced during the bouncing phase and find that the spectrum of curvature fluctuations in the model proposed originally to implement the ekpyrotic scenario has a large blue tilt (nR=3). Except for instabilities introduced on small scales, the result agrees with what is obtained by imposing continuity of the induced metric and of the extrinsic curvature across a constant scalar field (up to k2 corrections equal to the constant energy density) matching surface between the contracting and the expanding Einstein universes. We also discuss nonsingular cosmological solutions obtained when a Gauss-Bonnet term with a coefficient suitably dependent on the scalar matter field is added to the action in the Einstein frame with a potential for the scalar field present. In this scenario, nonsingular solutions are found which start in an asymptotically flat state, undergo a period of superexponential inflation, and end with a graceful exit. The spectrum of fluctuations is also calculated in this case.

Einstein's osmotic equilibrium of colloidal suspensions in conservative force fields

NASA Astrophysics Data System (ADS)

Fu, Jinxin; Ou-Yang, H. Daniel

2014-09-01

Predicted by Einstein in his 1905 paper on Brownian motion, colloidal particles in suspension reach osmotic equilibrium under gravity. The idea was demonstrated by J.B. Perrin to win Nobel Prize in Physics in 1926. We show Einstein's equation for osmotic equilibrium can be applied to colloids in a conservative force field generated by optical gradient forces. We measure the osmotic equation of state of 100nm Polystyrene latex particles in the presence of KCl salt and PEG polymer. We also obtain the osmotic compressibility, which is important for determining colloidal stability and the internal chemical potential, which is useful for predicting the phase transition of colloidal systems. This generalization allows for the use of any conservative force fields for systems ranging from colloidal systems to macromolecular solutions.

Surface singularities in Eddington-inspired Born-Infeld gravity.

PubMed

Pani, Paolo; Sotiriou, Thomas P

2012-12-21

Eddington-inspired Born-Infeld gravity was recently proposed as an alternative to general relativity that offers a resolution of spacetime singularities. The theory differs from Einstein's gravity only inside matter due to nondynamical degrees of freedom, and it is compatible with all current observations. We show that the theory is reminiscent of Palatini f(R) gravity and that it shares the same pathologies, such as curvature singularities at the surface of polytropic stars and unacceptable Newtonian limit. This casts serious doubt on its viability.

Exploring the Structure and Evolution of the Universe: Multi-Band Profiles of the Known Gamma-Ray Pulsars

NASA Technical Reports Server (NTRS)

1998-01-01

As summarized in this pamphlet, some of the far-reaching underlying issues to be addressed include: What is the origin of the universe and its destiny; Why is the universe lumpy; How did the known structures of the universe evolve; How do galaxies evolve; How do massive black holes grow; How did the elemental composition of the universe evolve; What is the structure and behavior of matter in the extreme; and Is Einstein's general relativity theory right.

Does the planck mass run on the cosmological-horizon scale?

PubMed

Robbers, Georg; Afshordi, Niayesh; Doran, Michael

2008-03-21

Einstein's theory of general relativity contains a universal value of the Planck mass. However, one may envisage that in alternative theories of gravity the effective value of the Planck mass (or Newton's constant), which quantifies the coupling of matter to metric perturbations, can run on the cosmological-horizon scale. In this Letter, we study the consequences of a glitch in the Planck mass from subhorizon to superhorizon scales. We show that current cosmological observations severely constrain this glitch to less than 1.2%.

Gravitational-Wave Astronomy

NASA Technical Reports Server (NTRS)

Kelly, Bernard J.

2010-01-01

Einstein's General Theory of Relativity is our best classical description of gravity, and informs modern astronomy and astrophysics at all scales: stellar, galactic, and cosmological. Among its surprising predictions is the existence of gravitational waves -- ripples in space-time that carry energy and momentum away from strongly interacting gravitating sources. In my talk, I will give an overview of the properties of this radiation, recent breakthroughs in computational physics allowing us to calculate the waveforms from galactic mergers, and the prospect of direct observation with interferometric detectors such as LIGO and LISA.

Tracking Gravity Probe B gyroscope polhode motion

NASA Technical Reports Server (NTRS)

Keiser, George M.; Parkinson, Bradford W.; Cohen, Clark E.

1990-01-01

The superconducting Gravity Probe B spacecraft is being developed to measure two untested predictions of Einstein's theory of general relativity by using orbiting gyroscopes; it possesses an intrinsic magnetic field which rotates with the rotor and is fixed with respect to the rotor body frame. In this paper, the path of the rotor spin axes is tracked using this trapped magnetic flux as a reference. Both the rotor motion and the magnetic field shape are estimated simultaneously, employing the higher order components of the magnetic field shape.

Covariant electrodynamics in linear media: Optical metric

NASA Astrophysics Data System (ADS)

Thompson, Robert T.

2018-03-01

While the postulate of covariance of Maxwell's equations for all inertial observers led Einstein to special relativity, it was the further demand of general covariance—form invariance under general coordinate transformations, including between accelerating frames—that led to general relativity. Several lines of inquiry over the past two decades, notably the development of metamaterial-based transformation optics, has spurred a greater interest in the role of geometry and space-time covariance for electrodynamics in ponderable media. I develop a generally covariant, coordinate-free framework for electrodynamics in general dielectric media residing in curved background space-times. In particular, I derive a relation for the spatial medium parameters measured by an arbitrary timelike observer. In terms of those medium parameters I derive an explicit expression for the pseudo-Finslerian optical metric of birefringent media and show how it reduces to a pseudo-Riemannian optical metric for nonbirefringent media. This formulation provides a basis for a unified approach to ray and congruence tracing through media in curved space-times that may smoothly vary among positively refracting, negatively refracting, and vacuum.

Education for Einstein's World.

ERIC Educational Resources Information Center

Barry, Marie Myles

Einstein, translated into a philosophy of education, views the factors governing man's qualities--his genes, his parents, his neighborhood, his church, his country, his world--as relative forces in his development, susceptible to infinite growth, and depending upon various combinations of experience. These experiences, in turn, depend upon nature…

An introduction to tensor calculus, relativity and cosmology /3rd edition/

NASA Astrophysics Data System (ADS)

Lawden, D. F.

This textbook introduction to the principles of special relativity proceeds within the context of cartesian tensors. Newton's laws of motion are reviewed, as are the Lorentz transformations, Minkowski space-time, and the Fitzgerald contraction. Orthogonal transformations are described, and invariants, gradients, tensor derivatives, contraction, scalar products, divergence, pseudotensors, vector products, and curl are defined. Special relativity mechanics are explored in terms of mass, momentum, the force vector, the Lorentz transformation equations for force, calculations for photons and neutrinos, the development of the Lagrange and Hamilton equations, and the energy-momentum tensor. Electrodynamics is investigated, together with general tensor calculus and Riemmanian space. The General Theory of Relativity is presented, along with applications to astrophysical phenomena such as black holes and gravitational waves. Finally, analytical discussions of cosmological problems are reviewed, particularly Einstein, de Sitter, and Friedmann universes, redshifts, event horizons, and the redshift.

Hidden simplicity of the gravity action

DOE PAGES

Cheung, Clifford; Remmen, Grant N.

2017-09-01

We derive new representations of the Einstein-Hilbert action in which graviton perturbation theory is immensely simplified. To accomplish this, we recast the Einstein-Hilbert action as a theory of purely cubic interactions among gravitons and a single auxiliary field. The corresponding equations of motion are the Einstein field equations rewritten as two coupled first-order differential equations. Since all Feynman diagrams are cubic, we are able to derive new off-shell recursion relations for tree-level graviton scattering amplitudes. With a judicious choice of gauge fixing, we then construct an especially compact form for the Einstein-Hilbert action in which all graviton interactions are simplymore » proportional to the graviton kinetic term. Our results apply to graviton perturbations about an arbitrary curved background spacetime.« less

Hidden simplicity of the gravity action

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheung, Clifford; Remmen, Grant N.

We derive new representations of the Einstein-Hilbert action in which graviton perturbation theory is immensely simplified. To accomplish this, we recast the Einstein-Hilbert action as a theory of purely cubic interactions among gravitons and a single auxiliary field. The corresponding equations of motion are the Einstein field equations rewritten as two coupled first-order differential equations. Since all Feynman diagrams are cubic, we are able to derive new off-shell recursion relations for tree-level graviton scattering amplitudes. With a judicious choice of gauge fixing, we then construct an especially compact form for the Einstein-Hilbert action in which all graviton interactions are simplymore » proportional to the graviton kinetic term. Our results apply to graviton perturbations about an arbitrary curved background spacetime.« less

Evolution of Cosmology

NASA Astrophysics Data System (ADS)

Ross, Charles H.

2005-04-01

Aristotle thought that the universe was finite and Earth centered. Newton thought that it was infinite. Einstein guessed that the universe was finite, spherical, static, warped, and closed. Hubble's 1930 discovery of the expanding universe, Penzias and Wilson's 1968 discovery of the isotropic CMB, and measurements on light element abundances, however, established a big bang origin. Vera Rubin's 1980 dark matter discovery significantly impacted contending theories. However, 1998 is the year when sufficiently accurate supernova and primordial deuterium data was available to truly explore the universe. CMB anisotropy measurements further extended our cosmological database in 2003. On the theoretical side, Friedmann's 1922 perturbation solution of Einstein's general relativity equations for a static universe has shaped the thought and direction in cosmology for the past 80 years. It describes 3D space as a dynamic function of time. However, 80 years of trying to fit Friedmann's solution to observational data has been a bumpy road - resulting in such counter-intuitive, but necessary, features as rapid inflation, precision tuning, esoteric dark matter, and an accelerating input of esoteric dark energy.

A comparative analysis of perspectives of Mileva Maric Einstein

NASA Astrophysics Data System (ADS)

Barnett, Carol C.

This dissertation examines the controversy surrounding Mileva Maric Einstein and the allegations subsequent to the publication of love letters during the time that Mileva Maric and Albert Einstein were students and during the early years of their marriage. It also examines the role of women in science from a historical perspective. Chapter One surveys the history of women in science from antiquity to the late nineteenth century and the patterns of gender related and restricting practices such as education, publication, the problem of mentoring and the issue of the lack of historical recognition. Chapter Two provides a comparative analyses between the lives of Mileva Maric Einstein and Marie Sklodowska Curie. Both had very similar social and educational backgrounds yet Marie Curie was able to work and publish jointly with her husband and received (although belatedly) international recognition for her work. On the other hand, Mileva Maric Einstein was never able to complete her degree and lived a life of obscurity and unfulfilled professional dreams. Both highly educated and intelligent women, but with drastically different outcomes in their professional and personal lives. Chapter Three examines the one book devoted to the life of Mileva Maric Einstein, Im Schatten Albert Einsteins: Das Tragische Leben der Mileva Einstein-Maric (In The Shadow of Albert Einstein: The Tragic Life of Mileva Maric), by Desanka Trbuhovic-Gjuric, Paul Haupt Publishers, 1985. It addresses the subjective as well as constructive and destructive criticisms of the various critical camps and provides examples of the statements made by the author which prompted a controversy within the academic and scientific communities. Appropriate responses are provided from various members of the scientific community to reflect the diversity of opinion and the intensity of the debate. Chapter Four addresses the problem of historicity and various interpretations of evidence which might suggest that the role of Mileva Maric was indeed more than just emotional spousal support for the scientific ideas of Albert Einstein. This chapter also details various lines and quotes from the book on Maric Einstein and also from the love letters shared between she and Albert Einstein to provide an indepth account of what evidence we have of possible professional collaboration.

Equation of state of dark energy in f (R ) gravity

NASA Astrophysics Data System (ADS)

Takahashi, Kazufumi; Yokoyama, Jun'ichi

2015-04-01

f (R ) gravity is one of the simplest generalizations of general relativity, which may explain the accelerated cosmic expansion without introducing a cosmological constant. Transformed into the Einstein frame, a new scalar degree of freedom appears and it couples with matter fields. In order for f (R ) theories to pass the local tests of general relativity, it has been known that the chameleon mechanism with a so-called thin-shell solution must operate. If the thin-shell constraint is applied to a cosmological situation, it has been claimed that the equation-of-state parameter of dark energy w must be extremely close to -1 . We argue this is due to the incorrect use of the Poisson equation, which is valid only in the static case. By solving the correct Klein-Gordon equation perturbatively, we show that a thin-shell solution exists even if w deviates appreciably from -1 .

New classes of modified teleparallel gravity models

NASA Astrophysics Data System (ADS)

Bahamonde, Sebastian; Böhmer, Christian G.; Krššák, Martin

2017-12-01

New classes of modified teleparallel theories of gravity are introduced. The action of this theory is constructed to be a function of the irreducible parts of torsion f (Tax ,Tten ,Tvec), where Tax ,Tten and Tvec are squares of the axial, tensor and vector components of torsion, respectively. This is the most general (well-motivated) second order teleparallel theory of gravity that can be constructed from the torsion tensor. Different particular second order theories can be recovered from this theory such as new general relativity, conformal teleparallel gravity or f (T) gravity. Additionally, the boundary term B which connects the Ricci scalar with the torsion scalar via R = - T + B can also be incorporated into the action. By performing a conformal transformation, it is shown that the two unique theories which have an Einstein frame are either the teleparallel equivalent of general relativity or f (- T + B) = f (R) gravity, as expected.

Brown-York quasilocal energy in Lanczos-Lovelock gravity and black hole horizons

NASA Astrophysics Data System (ADS)

Chakraborty, Sumanta; Dadhich, Naresh

2015-12-01

A standard candidate for quasilocal energy in general relativity is the Brown-York energy, which is essentially a two dimensional surface integral of the extrinsic curvature on the two-boundary of a spacelike hypersurface referenced to flat spacetime. Several years back one of us had conjectured that the black hole horizon is defined by equipartition of gravitational and non-gravitational energy. By employing the above definition of quasilocal Brown-York energy, we have verified the equipartition conjecture for static charged and charged axi-symmetric black holes in general relativity. We have further generalized the Brown-York formalism to all orders in Lanczos-Lovelock theories of gravity and have verified the conjecture for pure Lovelock charged black hole in all even d = 2 m + 2 dimensions, where m is the degree of Lovelock action. It turns out that the equipartition conjecture works only for pure Lovelock, and not for Einstein-Lovelock black holes.

Geometrothermodynamics for black holes and de Sitter space

NASA Astrophysics Data System (ADS)

Kurihara, Yoshimasa

2018-02-01

A general method to extract thermodynamic quantities from solutions of the Einstein equation is developed. In 1994, Wald established that the entropy of a black hole could be identified as a Noether charge associated with a Killing vector of a global space-time (pseudo-Riemann) manifold. We reconstruct Wald's method using geometrical language, e.g., via differential forms defined on the local space-time (Minkowski) manifold. Concurrently, the abstract thermodynamics are also reconstructed using geometrical terminology, which is parallel to general relativity. The correspondence between the thermodynamics and general relativity can be seen clearly by comparing the two expressions. This comparison requires a modification of Wald's method. The new method is applied to Schwarzschild, Kerr, and Kerr-Newman black holes and de Sitter space. The results are consistent with previous results obtained using various independent methods. This strongly supports the validity of the area theorem for black holes.

Dynamical behavior of the Tolman metrics in f (R ,T ) gravity

NASA Astrophysics Data System (ADS)

Hansraj, Sudan; Banerjee, Ayan

2018-05-01

We analyze the behavior of well-known stellar models within the context of f (R ,T ) modified theory of gravity, in which the gravitational Lagrangian is given by an arbitrary function of the Ricci scalar R and the trace of the energy-momentum tensor T , namely f (R ,T )=R +2 χ T for some constant χ . The equation of pressure isotropy in this theory is identical to that of the standard Einstein theory therefore all known metric potentials solving Einstein's equations are valid here. However, the pressure and energy density profiles are markedly different due to the presence of the term 2 χ T . The exact solutions to the corresponding static spherically symmetric field equations with a perfect fluid source are the well known Tolman solutions [Phys. Rev. 55, 364 (1939), 10.1103/PhysRev.55.364] in general relativity. To support the theoretical results, graphical representation are employed to investigate the physical viability of compact stars. Specifically we study the density and pressure profiles, the sound speed behavior as well as the energy conditions and mass behavior where appropriate. It is found that in some cases the f (R ,T ) model displays more pleasing behavior than its Einstein counterpart while in other cases the behavior is similar. In no case does the 2 χ T addition negatively impact the model's behavior.

Spherical shock waves in general relativity

NASA Astrophysics Data System (ADS)

Nutku, Y.

1991-11-01

We present the metric appropriate to a spherical shock wave in the framework of general relativity. This is a Petrov type-N vacuum solution of the Einstein field equations where the metric is continuous across the shock and the Riemann tensor suffers a step-function discontinuity. Spherical gravitational waves are described by type-N Robinson-Trautman metrics. However, for shock waves the Robinson-Trautman solutions are unacceptable because the metric becomes discontinuous in the Robinson-Trautman coordinate system. Other coordinate systems that have so far been introduced for describing Robinson-Trautman solutions also suffer from the same defect. We shall present the C0-form of the metric appropriate to spherical shock waves using Penrose's approach of identification with warp. Further extensions of Penrose's method yield accelerating, as well as coupled electromagnetic-gravitational shock-wave solutions.

Black Hole Mergers, Gravitational Waves, and Multi-Messenger Astronomy

NASA Technical Reports Server (NTRS)

Centrella, Joan M.

2010-01-01

The final merger of two black holes is expected to be the strongest source of gravitational waves for both ground-based detectors such as LIGO and VIRGO, as well as the space-based LISA. Since the merger takes place in the regime of strong dynamical gravity, computing the resulting gravitational waveforms requires solving the full Einstein equations of general relativity on a computer. Although numerical codes designed to simulate black hole mergers were plagued for many years by a host of instabilities, recent breakthroughs have conquered these problems and opened up this field dramatically. This talk will focus on the resulting gold rush of new results that is revealing the dynamics and waveforms of binary black hole mergers, and their applications in gravitational wave detection, astrophysics, and testing general relativity.

Gravity Probe B: final results of a space experiment to test general relativity.

PubMed

Everitt, C W F; DeBra, D B; Parkinson, B W; Turneaure, J P; Conklin, J W; Heifetz, M I; Keiser, G M; Silbergleit, A S; Holmes, T; Kolodziejczak, J; Al-Meshari, M; Mester, J C; Muhlfelder, B; Solomonik, V G; Stahl, K; Worden, P W; Bencze, W; Buchman, S; Clarke, B; Al-Jadaan, A; Al-Jibreen, H; Li, J; Lipa, J A; Lockhart, J M; Al-Suwaidan, B; Taber, M; Wang, S

2011-06-03

Gravity Probe B, launched 20 April 2004, is a space experiment testing two fundamental predictions of Einstein's theory of general relativity (GR), the geodetic and frame-dragging effects, by means of cryogenic gyroscopes in Earth orbit. Data collection started 28 August 2004 and ended 14 August 2005. Analysis of the data from all four gyroscopes results in a geodetic drift rate of -6601.8±18.3  mas/yr and a frame-dragging drift rate of -37.2±7.2  mas/yr, to be compared with the GR predictions of -6606.1  mas/yr and -39.2  mas/yr, respectively ("mas" is milliarcsecond; 1  mas=4.848×10(-9)  rad).

Anomalous pinch of turbulent plasmas driven by the magnetic-drift-induced Lorentz force through the Stokes-Einstein relation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Shaojie, E-mail: wangsj@ustc.edu.cn

It is found that the Lorentz force generated by the magnetic drift drives a generic plasma pinch flux of particle, energy and momentum through the Stokes-Einstein relation. The proposed theoretical model applies for both electrons and ions, trapped particles, and passing particles. An anomalous parallel current pinch due to the electrostatic turbulence with long parallel wave-length is predicted.

Dynamical preparation of Einstein-Podolsky-Rosen entanglement in two-well Bose-Einstein condensates

NASA Astrophysics Data System (ADS)

Opanchuk, B.; He, Q. Y.; Reid, M. D.; Drummond, P. D.

2012-08-01

We propose to generate Einstein-Podolsky-Rosen (EPR) entanglement between groups of atoms in a two-well Bose-Einstein condensate using a dynamical process similar to that employed in quantum optics. A local nonlinear S-wave scattering interaction has the effect of creating spin squeezing at each well, while a tunneling coupling, analogous to a beam splitter in optics, introduces an interference between these fields that causes interwell entanglement. We consider two internal modes at each well so that the entanglement can be detected by measuring a reduction in the variances of the sums of local Schwinger spin observables. As is typical of continuous variable (CV) entanglement, the entanglement is predicted to increase with atom number. It becomes sufficiently strong at higher numbers of atoms so that the EPR paradox and steering nonlocality can be realized. The entanglement is predicted using an analytical approach and, for larger atom numbers, using stochastic simulations based on a truncated Wigner function approximation. We find generally that strong tunneling is favorable, and that entanglement persists and is even enhanced in the presence of realistic nonlinear losses.

Exact solutions with AdS asymptotics of Einstein and Einstein-Maxwell gravity minimally coupled to a scalar field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cadoni, Mariano; Serra, Matteo; Mignemi, Salvatore

We propose a general method for solving exactly the static field equations of Einstein and Einstein-Maxwell gravity minimally coupled to a scalar field. Our method starts from an ansatz for the scalar field profile, and determines, together with the metric functions, the corresponding form of the scalar self-interaction potential. Using this method we prove a new no-hair theorem about the existence of hairy black-hole and black-brane solutions and derive broad classes of static solutions with radial symmetry of the theory, which may play an important role in applications of the AdS/CFT correspondence to condensed matter and strongly coupled QFTs. Thesemore » solutions include: (1) four- or generic (d+2)-dimensional solutions with planar, spherical or hyperbolic horizon topology; (2) solutions with anti-de Sitter, domain wall and Lifshitz asymptotics; (3) solutions interpolating between an anti-de Sitter spacetime in the asymptotic region and a domain wall or conformal Lifshitz spacetime in the near-horizon region.« less

Remarks on the "Non-canonicity Puzzle": Lagrangian Symmetries of the Einstein-Hilbert Action

NASA Astrophysics Data System (ADS)

Kiriushcheva, N.; Komorowski, P. G.; Kuzmin, S. V.

2012-07-01

Given the non-canonical relationship between variables used in the Hamiltonian formulations of the Einstein-Hilbert action (due to Pirani, Schild, Skinner (PSS) and Dirac) and the Arnowitt-Deser-Misner (ADM) action, and the consequent difference in the gauge transformations generated by the first-class constraints of these two formulations, the assumption that the Lagrangians from which they were derived are equivalent leads to an apparent contradiction that has been called "the non-canonicity puzzle". In this work we shall investigate the group properties of two symmetries derived for the Einstein-Hilbert action: diffeomorphism, which follows from the PSS and Dirac formulations, and the one that arises from the ADM formulation. We demonstrate that unlike the diffeomorphism transformations, the ADM transformations (as well as others, which can be constructed for the Einstein-Hilbert Lagrangian using Noether's identities) do not form a group. This makes diffeomorphism transformations unique (the term "canonical" symmetry might be suggested). If the two Lagrangians are to be called equivalent, canonical symmetry must be preserved. The interplay between general covariance and the canonicity of the variables used is discussed.

HST image of Gravitational Lens G2237 + 305 or 'Einstein Cross'

NASA Technical Reports Server (NTRS)

1990-01-01

European Space Agency (ESA) Faint Object Camera (FOC) science image was taken from the Hubble Space Telescope (HST) of Gravitational Lens G2237 + 305 or 'Einstein Cross'. The gravitational lens G2237 + 305 or 'Einstein Cross' shows four images of a very distant quasar which has been multiple-imaged by a relatively nearby galaxy acting as a gravitational lens. The angular separation between the upper and lower images is 1.6 arc seconds. Photo was released from Goddard Space Flight Center (GSFC) 09-12-90.

De Sitter Invariant Special Relativity

NASA Astrophysics Data System (ADS)

Yan, Mu-Lin

2015-06-01

Einstein's Special Relativity is one of the cornerstones of modern physics. There is one universal parameter c (i.e., speed of light) in the Einstein's Special Relativity (E-SR), which serves as the maximal velocity of physics. One might be curious about whether there is another universal parameter R that serves as the maximal length in physics besides the universal maximal velocity limit c. The answer is yes. This book intends to describe a special theory of relativity with two universal parameters c and R. Such a theory is called the de Sitter Invariant Special Relativity, or the Special Relativity with Cosmology Constant...

Weyl relativity: a novel approach to Weyl's ideas

NASA Astrophysics Data System (ADS)

Barceló, Carlos; Carballo-Rubio, Raúl; Garay, Luis J.

2017-06-01

In this paper we revisit the motivation and construction of a unified theory of gravity and electromagnetism, following Weyl's insights regarding the appealing potential connection between the gauge invariance of electromagnetism and the conformal invariance of the gravitational field. We highlight that changing the local symmetry group of spacetime permits to construct a theory in which these two symmetries are combined into a putative gauge symmetry but with second-order field equations and non-trivial mass scales, unlike the original higher-order construction by Weyl. We prove that the gravitational field equations are equivalent to the (trace-free) Einstein field equations, ensuring their compatibility with known tests of general relativity. As a corollary, the effective cosmological constant is rendered radiatively stable due to Weyl invariance. A novel phenomenological consequence characteristic of this construction, potentially relevant for cosmological observations, is the existence of an energy scale below which effects associated with the non-integrability of spacetime distances, and an effective mass for the electromagnetic field, appear simultaneously (as dual manifestations of the use of Weyl connections). We explain how former criticisms against Weyl's ideas lose most of their power in its present reincarnation, which we refer to as Weyl relativity, as it represents a Weyl-invariant, unified description of both the Einstein and Maxwell field equations.

Weyl relativity: a novel approach to Weyl's ideas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barceló, Carlos; Carballo-Rubio, Raúl; Garay, Luis J., E-mail: carlos@iaa.es, E-mail: raul.carballo-rubio@uct.ac.za, E-mail: luisj.garay@ucm.es

In this paper we revisit the motivation and construction of a unified theory of gravity and electromagnetism, following Weyl's insights regarding the appealing potential connection between the gauge invariance of electromagnetism and the conformal invariance of the gravitational field. We highlight that changing the local symmetry group of spacetime permits to construct a theory in which these two symmetries are combined into a putative gauge symmetry but with second-order field equations and non-trivial mass scales, unlike the original higher-order construction by Weyl. We prove that the gravitational field equations are equivalent to the (trace-free) Einstein field equations, ensuring their compatibilitymore » with known tests of general relativity. As a corollary, the effective cosmological constant is rendered radiatively stable due to Weyl invariance. A novel phenomenological consequence characteristic of this construction, potentially relevant for cosmological observations, is the existence of an energy scale below which effects associated with the non-integrability of spacetime distances, and an effective mass for the electromagnetic field, appear simultaneously (as dual manifestations of the use of Weyl connections). We explain how former criticisms against Weyl's ideas lose most of their power in its present reincarnation, which we refer to as Weyl relativity, as it represents a Weyl-invariant, unified description of both the Einstein and Maxwell field equations.« less

Trouble with the Lorentz law of force: incompatibility with special relativity and momentum conservation.

PubMed

Mansuripur, Masud

2012-05-11

The Lorentz law of force is the fifth pillar of classical electrodynamics, the other four being Maxwell's macroscopic equations. The Lorentz law is the universal expression of the force exerted by electromagnetic fields on a volume containing a distribution of electrical charges and currents. If electric and magnetic dipoles also happen to be present in a material medium, they are traditionally treated by expressing the corresponding polarization and magnetization distributions in terms of bound-charge and bound-current densities, which are subsequently added to free-charge and free-current densities, respectively. In this way, Maxwell's macroscopic equations are reduced to his microscopic equations, and the Lorentz law is expected to provide a precise expression of the electromagnetic force density on material bodies at all points in space and time. This Letter presents incontrovertible theoretical evidence of the incompatibility of the Lorentz law with the fundamental tenets of special relativity. We argue that the Lorentz law must be abandoned in favor of a more general expression of the electromagnetic force density, such as the one discovered by Einstein and Laub in 1908. Not only is the Einstein-Laub formula consistent with special relativity, it also solves the long-standing problem of "hidden momentum" in classical electrodynamics.

Strong Gravitational Lensing: Relativity in Action

NASA Astrophysics Data System (ADS)

Wambsganss, Joachim

2009-05-01

Deflection of light by gravity was predicted by Einstein's Theory of General Relativity and observationally confirmed in 1919. In the following decades, various aspects of the gravitational lens effect were explored theoretically, among them measuring the Hubble constant from multiple images of a background source, making use of the magnifying effect as a gravitational telescope, or the possibility of a "relativistic eclipse" as a perfect test of GR. Only in 1979, gravitational lensing became an observational science when the first doubly imaged quasar was discovered. Today lensing is a booming part of astrophysics and cosmology. A whole suite of strong lensing phenomena have been investigated since: multiple quasars, giant luminous arcs, Einstein rings, quasar microlensing, and galactic microlensing. The most recent lensing application is the detection of extrasolar planets. Lensing has contributed significant new results in areas as different as the cosmological distance scale, mass determination of galaxy clusters, physics of quasars, searches for dark matter in galaxy halos, structure of the Milky Way, stellar atmospheres and exoplanets. A guided tour through some of these applications -- with both photometric and astrometric signatures of lensing being discussed -- will illustrate how gravitational lensing has established itself as a very useful universal astrophysical tool.

Nonequilibrium Brownian motion beyond the effective temperature.

PubMed

Gnoli, Andrea; Puglisi, Andrea; Sarracino, Alessandro; Vulpiani, Angelo

2014-01-01

The condition of thermal equilibrium simplifies the theoretical treatment of fluctuations as found in the celebrated Einstein's relation between mobility and diffusivity for Brownian motion. Several recent theories relax the hypothesis of thermal equilibrium resulting in at least two main scenarios. With well separated timescales, as in aging glassy systems, equilibrium Fluctuation-Dissipation Theorem applies at each scale with its own "effective" temperature. With mixed timescales, as for example in active or granular fluids or in turbulence, temperature is no more well-defined, the dynamical nature of fluctuations fully emerges and a Generalized Fluctuation-Dissipation Theorem (GFDT) applies. Here, we study experimentally the mixed timescale regime by studying fluctuations and linear response in the Brownian motion of a rotating intruder immersed in a vibro-fluidized granular medium. Increasing the packing fraction, the system is moved from a dilute single-timescale regime toward a denser multiple-timescale stage. Einstein's relation holds in the former and is violated in the latter. The violation cannot be explained in terms of effective temperatures, while the GFDT is able to impute it to the emergence of a strong coupling between the intruder and the surrounding fluid. Direct experimental measurements confirm the development of spatial correlations in the system when the density is increased.

On the history of the quantum. Introduction to the HQ2 special issue

NASA Astrophysics Data System (ADS)

van Dongen, Jeroen; Dieks, Dennis; Uffink, Jos; Kox, A. J.

The historiography of quantum theory exhibits a period of intense activity that started in the 1960s, with the Archives for the History of Quantum Physics project, and continued with the work of scholars like Max Jammer, Martin J. Klein, John Heilbron, Paul Forman and Thomas Kuhn. At the end of the 1970s, however, interest of historians seems to have shifted away, even if there have been notable exceptions, such as the multi-volume work by Jagdish Mehra and Helmut Rechenberg, and monographs like those of Olivier Darrigol and Mara Beller. Perhaps this development has had to do with a diminishing number of scholars possessing the necessary technical skills in physics together with historical sensitivity. Moreover, many historians of physics in this period have focused their interest on another subject, namely the development of the theory of relativity. Stimulated by the start of the Einstein Papers Project, and initiated by pioneers such as John Stachel and John Norton around 1980, very soon a dedicated group of scholars devoted time and energy to analyzing the genesis and development of general relativity, and other aspects of Einstein's science.

A massive binary black-hole system in OJ 287 and a test of general relativity.

PubMed

Valtonen, M J; Lehto, H J; Nilsson, K; Heidt, J; Takalo, L O; Sillanpää, A; Villforth, C; Kidger, M; Poyner, G; Pursimo, T; Zola, S; Wu, J-H; Zhou, X; Sadakane, K; Drozdz, M; Koziel, D; Marchev, D; Ogloza, W; Porowski, C; Siwak, M; Stachowski, G; Winiarski, M; Hentunen, V-P; Nissinen, M; Liakos, A; Dogru, S

2008-04-17

Tests of Einstein's general theory of relativity have mostly been carried out in weak gravitational fields where the space-time curvature effects are first-order deviations from Newton's theory. Binary pulsars provide a means of probing the strong gravitational field around a neutron star, but strong-field effects may be best tested in systems containing black holes. Here we report such a test in a close binary system of two candidate black holes in the quasar OJ 287. This quasar shows quasi-periodic optical outbursts at 12-year intervals, with two outburst peaks per interval. The latest outburst occurred in September 2007, within a day of the time predicted by the binary black-hole model and general relativity. The observations confirm the binary nature of the system and also provide evidence for the loss of orbital energy in agreement (within 10 per cent) with the emission of gravitational waves from the system. In the absence of gravitational wave emission the outburst would have happened 20 days later.

Modified fluctuation-dissipation and Einstein relation at nonequilibrium steady states

NASA Astrophysics Data System (ADS)

Chaudhuri, Debasish; Chaudhuri, Abhishek

2012-02-01

Starting from the pioneering work of Agarwal [G. S. Agarwal, Zeitschrift für PhysikEPJAFV1434-600110.1007/BF01391621 252, 25 (1972)], we present a unified derivation of a number of modified fluctuation-dissipation relations (MFDR) that relate response to small perturbations around nonequilibrium steady states to steady-state correlations. Using this formalism we show the equivalence of velocity forms of MFDR derived using continuum Langevin and discrete master equation dynamics. The resulting additive correction to the Einstein relation is exemplified using a flashing ratchet model of molecular motors.

Axion as a cold dark matter candidate: analysis to third order perturbation for classical axion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noh, Hyerim; Hwang, Jai-chan; Park, Chan-Gyung, E-mail: hr@kasi.re.kr, E-mail: jchan@knu.ac.kr, E-mail: park.chan.gyung@gmail.com

2015-12-01

We investigate aspects of axion as a coherently oscillating massive classical scalar field by analyzing third order perturbations in Einstein's gravity in the axion-comoving gauge. The axion fluid has its characteristic pressure term leading to an axion Jeans scale which is cosmologically negligible for a canonical axion mass. Our classically derived axion pressure term in Einstein's gravity is identical to the one derived in the non-relativistic quantum mechanical context in the literature. We present the general relativistic continuity and Euler equations for an axion fluid valid up to third order perturbation. Equations for axion are exactly the same as thatmore » of a zero-pressure fluid in Einstein's gravity except for an axion pressure term in the Euler equation. Our analysis includes the cosmological constant.« less

Black holes in vector-tensor theories and their thermodynamics

NASA Astrophysics Data System (ADS)

Fan, Zhong-Ying

2018-01-01

In this paper, we study Einstein gravity either minimally or non-minimally coupled to a vector field which breaks the gauge symmetry explicitly in general dimensions. We first consider a minimal theory which is simply the Einstein-Proca theory extended with a quartic self-interaction term for the vector field. We obtain its general static maximally symmetric black hole solution and study the thermodynamics using Wald formalism. The aspects of the solution are much like a Reissner-Nordstrøm black hole in spite of that a global charge cannot be defined for the vector. For non-minimal theories, we obtain a lot of exact black hole solutions, depending on the parameters of the theories. In particular, many of the solutions are general static and have maximal symmetry. However, there are some subtleties and ambiguities in the derivation of the first laws because the existence of an algebraic degree of freedom of the vector in general invalids the Wald entropy formula. The thermodynamics of these solutions deserves further studies.

A parametrisation of modified gravity on nonlinear cosmological scales

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lombriser, Lucas, E-mail: llo@roe.ac.uk

2016-11-01

Viable modifications of gravity on cosmological scales predominantly rely on screening mechanisms to recover Einstein's Theory of General Relativity in the Solar System, where it has been well tested. A parametrisation of the effects of such modifications in the spherical collapse model is presented here for the use of modelling the modified nonlinear cosmological structure. The formalism allows an embedding of the different screening mechanisms operating in scalar-tensor theories through large values of the gravitational potential or its first or second derivatives as well as of linear suppression effects or more general transitions between modified and Einstein gravity limits. Eachmore » screening or suppression mechanism is parametrised by a time, mass, and environment dependent screening scale, an effective modified gravitational coupling in the fully unscreened limit that can be matched to linear theory, the exponent of a power-law radial profile of the screened coupling, determined by derivatives, symmetries, and potentials in the scalar field equation, and an interpolation rate between the screened and unscreened limits. Along with generalised perturbative methods, the parametrisation may be used to formulate a nonlinear extension to the linear parametrised post-Friedmannian framework to enable generalised tests of gravity with the wealth of observations from the nonlinear cosmological regime.« less

New insights on the matter-gravity coupling paradigm.

PubMed

Delsate, Térence; Steinhoff, Jan

2012-07-13

The coupling between matter and gravity in general relativity is given by a proportionality relation between the stress tensor and the geometry. This is an oriented assumption driven by the fact that both the stress tensor and the Einstein tensor are divergenceless. However, general relativity is in essence a nonlinear theory, so there is no obvious reason why the coupling to matter should be linear. On another hand, modified theories of gravity usually affect the vacuum dynamics, yet keep the coupling to matter linear. In this Letter, we address the implications of consistent nonlinear gravity-matter coupling. The Eddington-inspired Born-Infeld theory recently introduced by Bañados and Ferreira provides an enlightening realization of such coupling modifications. We find that this theory coupled to a perfect fluid reduces to general relativity coupled to a nonlinearly modified perfect fluid, leading to an ambiguity between modified coupling and modified equation of state. We discuss observational consequences of this degeneracy and argue that such a completion of general relativity is viable from both an experimental and theoretical point of view through energy conditions, consistency, and singularity-avoidance perspectives. We use these results to discuss the impact of changing the coupling paradigm.

Clausius entropy for arbitrary bifurcate null surfaces

NASA Astrophysics Data System (ADS)

Baccetti, Valentina; Visser, Matt

2014-02-01

Jacobson’s thermodynamic derivation of the Einstein equations was originally applied only to local Rindler horizons. But at least some parts of that construction can usefully be extended to give meaningful results for arbitrary bifurcate null surfaces. As presaged in Jacobson’s original article, this more general construction sharply brings into focus the questions: is entropy objectively ‘real’? Or is entropy in some sense subjective and observer-dependent? These innocent questions open a Pandora’s box of often inconclusive debate. A consensus opinion, though certainly not universally held, seems to be that Clausius entropy (thermodynamic entropy, defined via a Clausius relation {\\rm{d}}S = \\unicode{x111} Q/T) should be objectively real, but that the ontological status of statistical entropy (Shannon or von Neumann entropy) is much more ambiguous, and much more likely to be observer-dependent. This question is particularly pressing when it comes to understanding Bekenstein entropy (black hole entropy). To perhaps further add to the confusion, we shall argue that even the Clausius entropy can often be observer-dependent. In the current article we shall conclusively demonstrate that one can meaningfully assign a notion of Clausius entropy to arbitrary bifurcate null surfaces—effectively defining a ‘virtual Clausius entropy’ for arbitrary ‘virtual (local) causal horizons’. As an application, we see that we can implement a version of the generalized second law (GSL) for this virtual Clausius entropy. This version of GSL can be related to certain (nonstandard) integral variants of the null energy condition. Because the concepts involved are rather subtle, we take some effort in being careful and explicit in developing our framework. In future work we will apply this construction to generalize Jacobson’s derivation of the Einstein equations.

Causality and a -theorem constraints on Ricci polynomial and Riemann cubic gravities

NASA Astrophysics Data System (ADS)

Li, Yue-Zhou; Lü, H.; Wu, Jun-Bao

2018-01-01

In this paper, we study Einstein gravity extended with Ricci polynomials and derive the constraints on the coupling constants from the considerations of being ghost-free, exhibiting an a -theorem and maintaining causality. The salient feature is that Einstein metrics with appropriate effective cosmological constants continue to be solutions with the inclusion of such Ricci polynomials and the causality constraint is automatically satisfied. The ghost-free and a -theorem conditions can only be both met starting at the quartic order. We also study these constraints on general Riemann cubic gravities.

Warped product space-times

NASA Astrophysics Data System (ADS)

An, Xinliang; Wong, Willie Wai Yeung

2018-01-01

Many classical results in relativity theory concerning spherically symmetric space-times have easy generalizations to warped product space-times, with a two-dimensional Lorentzian base and arbitrary dimensional Riemannian fibers. We first give a systematic presentation of the main geometric constructions, with emphasis on the Kodama vector field and the Hawking energy; the construction is signature independent. This leads to proofs of general Birkhoff-type theorems for warped product manifolds; our theorems in particular apply to situations where the warped product manifold is not necessarily Einstein, and thus can be applied to solutions with matter content in general relativity. Next we specialize to the Lorentzian case and study the propagation of null expansions under the assumption of the dominant energy condition. We prove several non-existence results relating to the Yamabe class of the fibers, in the spirit of the black-hole topology theorem of Hawking–Galloway–Schoen. Finally we discuss the effect of the warped product ansatz on matter models. In particular we construct several cosmological solutions to the Einstein–Euler equations whose spatial geometry is generally not isotropic.

Black Hole Mergers and Gravitational Waves: Opening the New Frontier

NASA Technical Reports Server (NTRS)

Centrella, Joan

2012-01-01

The final merger of two black holes produces a powerful burst of gravitational waves, emitting more energy than all the stars in the observable universe combined. Since these mergers take place in the regime of strong dynamical gravity, computing the gravitational waveforms requires solving the full Einstein equations of general relativity on a computer. For more than 30 years, scientists tried to simulate these mergers using the methods of numerical relativity. The resulting computer codes were plagued by instabilities, causing them to crash well before the black holes in the binary could complete even a single orbit. In the past several years, this situation has changed dramatically, with a series of remarkable breakthroughs. This talk will highlight these breakthroughs and the resulting 'gold rush' of new results that is revealing the dynamics of binary black hole mergers, and their applications in gravitational wave detection, testing general relativity, and astrophysics.

Lorentz invariance with an invariant energy scale.

PubMed

Magueijo, João; Smolin, Lee

2002-05-13

We propose a modification of special relativity in which a physical energy, which may be the Planck energy, joins the speed of light as an invariant, in spite of a complete relativity of inertial frames and agreement with Einstein's theory at low energies. This is accomplished by a nonlinear modification of the action of the Lorentz group on momentum space, generated by adding a dilatation to each boost in such a way that the Planck energy remains invariant. The associated algebra has unmodified structure constants. We also discuss the resulting modifications of field theory and suggest a modification of the equivalence principle which determines how the new theory is embedded in general relativity.

Identifying time scales for violation/preservation of Stokes-Einstein relation in supercooled water

PubMed Central

Kawasaki, Takeshi; Kim, Kang

2017-01-01

The violation of the Stokes-Einstein (SE) relation D ~ (η/T)−1 between the shear viscosity η and the translational diffusion constant D at temperature T is of great importance for characterizing anomalous dynamics of supercooled water. Determining which time scales play key roles in the SE violation remains elusive without the measurement of η. We provide comprehensive simulation results of the dynamic properties involving η and D in the TIP4P/2005 supercooled water. This enabled the thorough identification of the appropriate time scales for the SE relation Dη/T. In particular, it is demonstrated that the temperature dependence of various time scales associated with structural relaxation, hydrogen bond breakage, stress relaxation, and dynamic heterogeneities can be definitely classified into only two classes. That is, we propose the generalized SE relations that exhibit “violation” or “preservation.” The classification depends on the examined time scales that are coupled or decoupled with the diffusion. On the basis of the classification, we explain the physical origins of the violation in terms of the increase in the plateau modulus and the nonexponentiality of stress relaxation. This implies that the mechanism of SE violation is attributed to the attained solidity upon supercooling, which is in accord with the growth of non-Gaussianity and spatially heterogeneous dynamics. PMID:28835918

Spacetime thermodynamics in the presence of torsion

NASA Astrophysics Data System (ADS)

Dey, Ramit; Liberati, Stefano; Pranzetti, Daniele

2017-12-01

It was shown by Jacobson in 1995 that the Einstein equation can be derived as a local constitutive equation for an equilibrium spacetime thermodynamics. With the aim to understand if such thermodynamical description is an intrinsic property of gravitation, many attempts have been made so far to generalize this treatment to a broader class of gravitational theories. Here we consider the case of the Einstein-Cartan theory as a prototype of theories with nonpropagating torsion. In doing so, we study the properties of Killing horizons in the presence of torsion, establish the notion of local causal horizon in Riemann-Cartan spacetimes, and derive the generalized Raychaudhuri equation for these kinds of geometries. Then, starting with the entropy that can be associated to these local causal horizons, we derive the Einstein-Cartan equation by implementing the Clausius equation. We outline two ways of proceeding with the derivation depending on whether we take torsion as a geometric field or as a matter field. In both cases we need to add internal entropy production terms to the Clausius equation as the shear and twist cannot be taken to be 0 a priori for our setup. This fact implies the necessity of a nonequilibrium thermodynamics treatment for the local causal horizon. Furthermore, it implies that a nonzero twist at the horizon in general contributes to the Hartle-Hawking tidal heating for black holes with possible implications for future observations.

Studying scientific thought experiments in their context: Albert Einstein and electromagnetic induction

NASA Astrophysics Data System (ADS)

Potters, Jan; Leuridan, Bert

2017-05-01

This article concerns the way in which philosophers study the epistemology of scientific thought experiments. Starting with a general overview of the main contemporary philosophical accounts, we will first argue that two implicit assumptions are present therein: first, that the epistemology of scientific thought experiments is solely concerned with factual knowledge of the world; and second, that philosophers should account for this in terms of the way in which individuals in general contemplate these thought experiments in thought. Our goal is to evaluate these assumptions and their implications using a particular case study: Albert Einstein's magnet-conductor thought experiment. We will argue that an analysis of this thought experiment based on these assumptions - as John Norton (1991) provides - is, in a sense, both misguided (the thought experiment by itself did not lead Einstein to factual knowledge of the world) and too narrow (to understand the thought experiment's epistemology, its historical context should also be taken into account explicitly). Based on this evaluation we propose an alternative philosophical approach to the epistemology of scientific thought experiments which is more encompassing while preserving what is of value in the dominant view.

On the Origin of the Spin of Planets and Stars and its Connection with Gravitomagnetism

NASA Astrophysics Data System (ADS)

Elbeze, Alexandre Chaloum

2012-06-01

The origin of the spin of planets and stars is, to a certain extent, still unexplained. In general, we attribute their rotation to the swirl of their constituent primitive gases. In this paper, we try to show that the rotation of celestial bodies depends only on their mass, apparent radius and tilt of their spin axes. We reach this conclusion within the framework of gravitomagnetism, implied by the Einstein's general relativity theory (GR). Our results show that it might possible, in principle, to calculate the mass of spinning objects by measuring their apparent radius, the speed of rotation and the tilt of the axis of rotation.

Quantum Interactive Dualism: The Libet and Einstein-Podolsky-RosenCausal Anomalies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stapp, Henry P.

2006-02-20

The "free will" data of Benjamin Libet and the predictionsof quantum theory considered by Einstein, Podolsky,and Rosen, both posepuzzles within aconceptual framework that, simultaneously, is compatiblewith the theory of relativity and allows human subjects to freely choosehow they will act. The quantum theoretic resolutions of these puzzles aredescribed.

Spacetime and gravitation.

NASA Astrophysics Data System (ADS)

Kopczyński, W.; Trautman, A.

This book is a revised translation of the Polish original "Czasoprzestrzeń i grawitacja", Warszawa (Poland), Państwowe Wydawnictwo Naukowe, 1984. Ideas about space and time are at the root of one's understanding of nature, both at the intuitive level of everyday experience and in the framework of sophisticated physical theories. These ideas have led to the development of geometry and its applications to physics. The contemporary physical theory of space and time, including its extention to the phenomena of gravitation, is Einstein's theory of relativity. The book is a short introduction to this theory. A great deal of emphasis is given to the geometrical aspects of relativity theory and its comparison with the Newtonian view of the world. There are short chapters on the origins of Einstein's theory, gravitational waves, cosmology, spinors and the Einstein-Cartan theory.

Intrinsic time quantum geometrodynamics

NASA Astrophysics Data System (ADS)

Ita, Eyo Eyo; Soo, Chopin; Yu, Hoi-Lai

2015-08-01

Quantum geometrodynamics with intrinsic time development and momentric variables is presented. An underlying SU(3) group structure at each spatial point regulates the theory. The intrinsic time behavior of the theory is analyzed, together with its ground state and primordial quantum fluctuations. Cotton-York potential dominates at early times when the universe was small; the ground state naturally resolves Penrose's Weyl curvature hypothesis, and thermodynamic and gravitational "arrows of time" point in the same direction. Ricci scalar potential corresponding to Einstein's general relativity emerges as a zero-point energy contribution. A new set of fundamental commutation relations without Planck's constant emerges from the unification of gravitation and quantum mechanics.

Viscosity of a concentrated suspension of rigid monosized particles

NASA Astrophysics Data System (ADS)

Brouwers, H. J. H.

2010-05-01

This paper addresses the relative viscosity of concentrated suspensions loaded with unimodal hard particles. So far, exact equations have only been put forward in the dilute limit, e.g., by Einstein [A. Einstein, Ann. Phys. 19, 289 (1906) (in German); Ann. Phys. 34, 591 (1911) (in German)] for spheres. For larger concentrations, a number of phenomenological models for the relative viscosity was presented, which depend on particle concentration only. Here, an original and exact closed form expression is derived based on geometrical considerations that predicts the viscosity of a concentrated suspension of monosized particles. This master curve for the suspension viscosity is governed by the relative viscosity-concentration gradient in the dilute limit (for spheres the Einstein limit) and by random close packing of the unimodal particles in the concentrated limit. The analytical expression of the relative viscosity is thoroughly compared with experiments and simulations reported in the literature, concerning both dilute and concentrated suspensions of spheres, and good agreement is found.

Stokes–Einstein relation and excess entropy in Al-rich Al-Cu melts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pasturel, A.; Jakse, N.

We investigate the conditions for the validity of the Stokes-Einstein relation that connects diffusivity to viscosity in melts using entropy-scaling relationships developed by Rosenfeld. Employing ab initio molecular dynamics simulations to determine transport and structural properties of liquid Al{sub 1−x}Cu{sub x} alloys (with composition x ≤ 0.4), we first show that reduced self-diffusion coefficients and viscosities, according to Rosenfeld's formulation, scale with the two-body approximation of the excess entropy except the reduced viscosity for x = 0.4. Then, we use our findings to evidence that the Stokes-Einstein relation using effective atomic radii is not valid in these alloys while its validity can be relatedmore » to the temperature dependence of the partial pair-excess entropies of both components. Finally, we derive a relation between the ratio of the self-diffusivities of the components and the ratio of their pair excess entropies.« less

Iontophoretic transport of oligonucleotides across human epidermal membrane: a study of the Nernst-Planck model.

PubMed

Li, S K; Ghanem, A H; Teng, C L; Hardee, G E; Higuchi, W I

2001-07-01

The objective of this study was to investigate the transport behavior of a series of oligonucleotides with human epidermal membrane (HEM) and to examine the applicability of the modified NERNST-PLANCK model to transdermal iontophoresis of these macromolecules. Iontophoretic transport experiments were first carried out in a synthetic model membrane system (Nuclepore membranes) with a four-electrode potentiostat to examine the baseline modified NERNST-PLANCK model. The modified NERNST-PLANCK model derived from the Einstein relation and the Stokes-Einstein equation taken from previous work did not hold for the oligonucleotides. Results obtained in the Nuclepore studies were, however, consistent with predictions of the modified NERNST-PLANCK model using the experimentally determined electromobilities and diffusion coefficients. The electromobilities of the oligonucleotides (determined by capillary electrophoresis) were found to be more than a factor of two smaller than expected from the Einstein relation between electromobilities and diffusion coefficients (the latter determined in diffusion cell experiments). A correlation between these electromobilities and the theoretical electromobilities estimated by considering the effects of counterion binding and the effects of mobility reduction according to colloid theory was also observed. These results suggest that the modified NERNST-PLANCK model predictions are satisfactory only when the electromobilities and the effective molecular size of the oligonucleotides are known and are used directly to predict the iontophoretically enhanced transport. Results with the HEM experiments generally agreed with model predictions based on the experimental electromobilities. The oligonucleotide HEM flux data also suggest the existence of pores with effective pore radii greater than the effective radii estimated in previous studies with small molecular weight model permeants.

Confirmation of general relativity on large scales from weak lensing and galaxy velocities.

PubMed

Reyes, Reinabelle; Mandelbaum, Rachel; Seljak, Uros; Baldauf, Tobias; Gunn, James E; Lombriser, Lucas; Smith, Robert E

2010-03-11

Although general relativity underlies modern cosmology, its applicability on cosmological length scales has yet to be stringently tested. Such a test has recently been proposed, using a quantity, E(G), that combines measures of large-scale gravitational lensing, galaxy clustering and structure growth rate. The combination is insensitive to 'galaxy bias' (the difference between the clustering of visible galaxies and invisible dark matter) and is thus robust to the uncertainty in this parameter. Modified theories of gravity generally predict values of E(G) different from the general relativistic prediction because, in these theories, the 'gravitational slip' (the difference between the two potentials that describe perturbations in the gravitational metric) is non-zero, which leads to changes in the growth of structure and the strength of the gravitational lensing effect. Here we report that E(G) = 0.39 +/- 0.06 on length scales of tens of megaparsecs, in agreement with the general relativistic prediction of E(G) approximately 0.4. The measured value excludes a model within the tensor-vector-scalar gravity theory, which modifies both Newtonian and Einstein gravity. However, the relatively large uncertainty still permits models within f(R) theory, which is an extension of general relativity. A fivefold decrease in uncertainty is needed to rule out these models.

Confirmation of general relativity on large scales from weak lensing and galaxy velocities

NASA Astrophysics Data System (ADS)

Reyes, Reinabelle; Mandelbaum, Rachel; Seljak, Uros; Baldauf, Tobias; Gunn, James E.; Lombriser, Lucas; Smith, Robert E.

2010-03-01

Although general relativity underlies modern cosmology, its applicability on cosmological length scales has yet to be stringently tested. Such a test has recently been proposed, using a quantity, EG, that combines measures of large-scale gravitational lensing, galaxy clustering and structure growth rate. The combination is insensitive to `galaxy bias' (the difference between the clustering of visible galaxies and invisible dark matter) and is thus robust to the uncertainty in this parameter. Modified theories of gravity generally predict values of EG different from the general relativistic prediction because, in these theories, the `gravitational slip' (the difference between the two potentials that describe perturbations in the gravitational metric) is non-zero, which leads to changes in the growth of structure and the strength of the gravitational lensing effect. Here we report that EG = 0.39+/-0.06 on length scales of tens of megaparsecs, in agreement with the general relativistic prediction of EG~0.4. The measured value excludes a model within the tensor-vector-scalar gravity theory, which modifies both Newtonian and Einstein gravity. However, the relatively large uncertainty still permits models within f() theory, which is an extension of general relativity. A fivefold decrease in uncertainty is needed to rule out these models.

Schwarzschild and Kerr solutions of Einstein's field equation: An Introduction

NASA Astrophysics Data System (ADS)

Heinicke, Christian; Hehl, Friedrich W.

2015-12-01

Starting from Newton's gravitational theory, we give a general introduction into the spherically symmetric solution of Einstein's vacuum field equation, the Schwarzschild(-Droste) solution, and into one specific stationary axially symmetric solution, the Kerr solution. The Schwarzschild solution is unique and its metric can be interpreted as the exterior gravitational field of a spherically symmetric mass. The Kerr solution is only unique if the multipole moments of its mass and its angular momentum take on prescribed values. Its metric can be interpreted as the exterior gravitational field of a suitably rotating mass distribution. Both solutions describe objects exhibiting an event horizon, a frontier of no return. The corresponding notion of a black hole is explained to some extent. Eventually, we present some generalizations of the Kerr solution.

Exact models for isotropic matter

NASA Astrophysics Data System (ADS)

Thirukkanesh, S.; Maharaj, S. D.

2006-04-01

We study the Einstein-Maxwell system of equations in spherically symmetric gravitational fields for static interior spacetimes. The condition for pressure isotropy is reduced to a recurrence equation with variable, rational coefficients. We demonstrate that this difference equation can be solved in general using mathematical induction. Consequently, we can find an explicit exact solution to the Einstein-Maxwell field equations. The metric functions, energy density, pressure and the electric field intensity can be found explicitly. Our result contains models found previously, including the neutron star model of Durgapal and Bannerji. By placing restrictions on parameters arising in the general series, we show that the series terminate and there exist two linearly independent solutions. Consequently, it is possible to find exact solutions in terms of elementary functions, namely polynomials and algebraic functions.

Black-Hole Binaries, Gravitational Waves, and Numerical Relativity

NASA Technical Reports Server (NTRS)

Kelly, Bernard J.; Centrella, Joan; Baker, John G.; Kelly, Bernard J.; vanMeter, James R.

2010-01-01

Understanding the predictions of general relativity for the dynamical interactions of two black holes has been a long-standing unsolved problem in theoretical physics. Black-hole mergers are monumental astrophysical events ' releasing tremendous amounts of energy in the form of gravitational radiation ' and are key sources for both ground- and spacebased gravitational wave detectors. The black-hole merger dynamics and the resulting gravitational waveforms can only he calculated through numerical simulations of Einstein's equations of general relativity. For many years, numerical relativists attempting to model these mergers encountered a host of problems, causing their codes to crash after just a fraction of a binary orbit cnuld be simulated. Recently ' however, a series of dramatic advances in numerical relativity has ' for the first time, allowed stable / robust black hole merger simulations. We chronicle this remarkable progress in the rapidly maturing field of numerical relativity, and the new understanding of black-hole binary dynamics that is emerging. We also discuss important applications of these fundamental physics results to astrophysics, to gravitationalwave astronomy, and in other areas.

Cosmological singularities and bounce in Cartan-Einstein theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lucat, Stefano; Prokopec, Tomislav, E-mail: s.lucat@students.uu.nl, E-mail: t.prokopec@uu.nl

We consider a generalized Einstein-Cartan theory, in which we add the unique covariant dimension four operators to general relativity that couples fermionic spin current to the torsion tensor (with an arbitrary strength). Since torsion is local and non-dynamical, when integrated out it yields an effective four-fermion interaction of the gravitational strength. We show how to renormalize the theory, in the one-loop perturbative expansion in generally curved space-times, obtaining the first order correction to the 2PI effective action in Schwinger-Keldysh ( in-in ) formalism. We then apply the renormalized theory to study the dynamics of a collapsing universe that begins inmore » a thermal state and find that—instead of a big crunch singularity—the Universe with torsion undergoes a bounce . We solve the dynamical equations (a) classically (without particle production); (b) including the production of fermions in a fixed background in the Hartree-Fock approximation and (c) including the quantum backreaction of fermions onto the background space-time. In the first and last cases the Universe undergoes a bounce. The production of fermions due to the coupling to a contracting homogeneous background speeds up the bounce, implying that the quantum contributions from fermions is negative, presumably because fermion production contributes negatively to the energy-momentum tensor. When compared with former works on the subject, our treatment is fully microscopic (namely, we treat fermions by solving the corresponding Dirac equations) and quantum (in the sense that we include fermionic loop contributions).« less

Cosmological singularities and bounce in Cartan-Einstein theory

NASA Astrophysics Data System (ADS)

Lucat, Stefano; Prokopec, Tomislav

2017-10-01

We consider a generalized Einstein-Cartan theory, in which we add the unique covariant dimension four operators to general relativity that couples fermionic spin current to the torsion tensor (with an arbitrary strength). Since torsion is local and non-dynamical, when integrated out it yields an effective four-fermion interaction of the gravitational strength. We show how to renormalize the theory, in the one-loop perturbative expansion in generally curved space-times, obtaining the first order correction to the 2PI effective action in Schwinger-Keldysh (in-in) formalism. We then apply the renormalized theory to study the dynamics of a collapsing universe that begins in a thermal state and find that—instead of a big crunch singularity—the Universe with torsion undergoes a bounce. We solve the dynamical equations (a) classically (without particle production); (b) including the production of fermions in a fixed background in the Hartree-Fock approximation and (c) including the quantum backreaction of fermions onto the background space-time. In the first and last cases the Universe undergoes a bounce. The production of fermions due to the coupling to a contracting homogeneous background speeds up the bounce, implying that the quantum contributions from fermions is negative, presumably because fermion production contributes negatively to the energy-momentum tensor. When compared with former works on the subject, our treatment is fully microscopic (namely, we treat fermions by solving the corresponding Dirac equations) and quantum (in the sense that we include fermionic loop contributions).

Bianchi type-I magnetized cosmological models for the Einstein-Boltzmann equation with the cosmological constant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ayissi, Raoul Domingo, E-mail: raoulayissi@yahoo.fr; Noutchegueme, Norbert, E-mail: nnoutch@yahoo.fr

Global solutions regular for the Einstein-Boltzmann equation on a magnetized Bianchi type-I cosmological model with the cosmological constant are investigated. We suppose that the metric is locally rotationally symmetric. The Einstein-Boltzmann equation has been already considered by some authors. But, in general Bancel and Choquet-Bruhat [Ann. Henri Poincaré XVIII(3), 263 (1973); Commun. Math. Phys. 33, 83 (1973)], they proved only the local existence, and in the case of the nonrelativistic Boltzmann equation. Mucha [Global existence of solutions of the Einstein-Boltzmann equation in the spatially homogeneous case. Evolution equation, existence, regularity and singularities (Banach Center Publications, Institute of Mathematics, Polish Academymore » of Science, 2000), Vol. 52] obtained a global existence result, for the relativistic Boltzmann equation coupled with the Einstein equations and using the Yosida operator, but confusing unfortunately with the nonrelativistic case. Noutchegueme and Dongho [Classical Quantum Gravity 23, 2979 (2006)] and Noutchegueme, Dongho, and Takou [Gen. Relativ. Gravitation 37, 2047 (2005)], have obtained a global solution in time, but still using the Yosida operator and considering only the uncharged case. Noutchegueme and Ayissi [Adv. Stud. Theor. Phys. 4, 855 (2010)] also proved a global existence of solutions to the Maxwell-Boltzmann system using the characteristic method. In this paper, we obtain using a method totally different from those used in the works of Noutchegueme and Dongho [Classical Quantum Gravity 23, 2979 (2006)], Noutchegueme, Dongho, and Takou [Gen. Relativ. Gravitation 37, 2047 (2005)], Noutchegueme and Ayissi [Adv. Stud. Theor. Phys. 4, 855 (2010)], and Mucha [Global existence of solutions of the Einstein-Boltzmann equation in the spatially homogeneous case. Evolution equation, existence, regularity and singularities (Banach Center Publications, Institute of Mathematics, Polish Academy of Science, 2000), Vol. 52] the global in time existence and uniqueness of a regular solution to the Einstein-Maxwell-Boltzmann system with the cosmological constant. We define and we use the weighted Sobolev separable spaces for the Boltzmann equation; some special spaces for the Einstein equations, then we clearly display all the proofs leading to the global existence theorems.« less

Bianchi type-I magnetized cosmological models for the Einstein-Boltzmann equation with the cosmological constant

NASA Astrophysics Data System (ADS)

Ayissi, Raoul Domingo; Noutchegueme, Norbert

2015-01-01

Global solutions regular for the Einstein-Boltzmann equation on a magnetized Bianchi type-I cosmological model with the cosmological constant are investigated. We suppose that the metric is locally rotationally symmetric. The Einstein-Boltzmann equation has been already considered by some authors. But, in general Bancel and Choquet-Bruhat [Ann. Henri Poincaré XVIII(3), 263 (1973); Commun. Math. Phys. 33, 83 (1973)], they proved only the local existence, and in the case of the nonrelativistic Boltzmann equation. Mucha [Global existence of solutions of the Einstein-Boltzmann equation in the spatially homogeneous case. Evolution equation, existence, regularity and singularities (Banach Center Publications, Institute of Mathematics, Polish Academy of Science, 2000), Vol. 52] obtained a global existence result, for the relativistic Boltzmann equation coupled with the Einstein equations and using the Yosida operator, but confusing unfortunately with the nonrelativistic case. Noutchegueme and Dongho [Classical Quantum Gravity 23, 2979 (2006)] and Noutchegueme, Dongho, and Takou [Gen. Relativ. Gravitation 37, 2047 (2005)], have obtained a global solution in time, but still using the Yosida operator and considering only the uncharged case. Noutchegueme and Ayissi [Adv. Stud. Theor. Phys. 4, 855 (2010)] also proved a global existence of solutions to the Maxwell-Boltzmann system using the characteristic method. In this paper, we obtain using a method totally different from those used in the works of Noutchegueme and Dongho [Classical Quantum Gravity 23, 2979 (2006)], Noutchegueme, Dongho, and Takou [Gen. Relativ. Gravitation 37, 2047 (2005)], Noutchegueme and Ayissi [Adv. Stud. Theor. Phys. 4, 855 (2010)], and Mucha [Global existence of solutions of the Einstein-Boltzmann equation in the spatially homogeneous case. Evolution equation, existence, regularity and singularities (Banach Center Publications, Institute of Mathematics, Polish Academy of Science, 2000), Vol. 52] the global in time existence and uniqueness of a regular solution to the Einstein-Maxwell-Boltzmann system with the cosmological constant. We define and we use the weighted Sobolev separable spaces for the Boltzmann equation; some special spaces for the Einstein equations, then we clearly display all the proofs leading to the global existence theorems.

Understanding Dark Energy

NASA Astrophysics Data System (ADS)

Greyber, Howard

2009-11-01

By careful analysis of the data from the WMAP satellite, scientists were surprised to determine that about 70% of the matter in our universe is in some unknown form, and labeled it Dark Energy. Earlier, in 1998, two separate international groups of astronomers studying Ia supernovae were even more surprised to be forced to conclude that an amazing smooth transition occurred, from the expected slowing down of the expansion of our universe (due to normal positive gravitation) to an accelerating expansion of the universe that began at at a big bang age of the universe of about nine billion years. In 1918 Albert Einstein stated that his Lambda term in his theory of general relativity was ees,``the energy of empty space,'' and represented a negative pressure and thus a negative gravity force. However my 2004 ``Strong'' Magnetic Field model (SMF) for the origin of magnetic fields at Combination Time (Astro-ph0509223 and 0509222) in our big bang universe produces a unique topology for Superclusters, having almost all the mass, visible and invisible, i.e. from clusters of galaxies down to particles with mass, on the surface of an ellipsoid surrounding a growing very high vacuum. If I hypothesize, with Einstein, that there exists a constant ees force per unit volume, then, gradually, as the universe expands from Combination Time, two effects occur (a) the volume of the central high vacuum region increases, and (b) the density of positive gravity particles in the central region of each Supercluster in our universe decreases dramatically. Thus eventually Einstein's general relativity theory's repulsive gravity of the central very high vacuum region becomes larger than the positive gravitational attraction of all the clusters of galaxies, galaxies, quasars, stars and plasma on the Supercluster shell, and the observed accelerating expansion of our universe occurs. This assumes that our universe is made up mostly of such Superclusters. It is conceivable that the high vacuum region between Superclusters also plays a role in adding extra repulsive gravity force. Note that cosmologist Stephen Hawking comments on his website that ``There is no reason to rule out negative pressure. This is just tension.''

Island of stability for consistent deformations of Einstein's gravity.

PubMed

Berkhahn, Felix; Dietrich, Dennis D; Hofmann, Stefan; Kühnel, Florian; Moyassari, Parvin

2012-03-30

We construct deformations of general relativity that are consistent and phenomenologically viable, since they respect, in particular, cosmological backgrounds. These deformations have unique symmetries in accordance with their Minkowski cousins (Fierz-Pauli theory for massive gravitons) and incorporate a background curvature induced self-stabilizing mechanism. Self-stabilization is essential in order to guarantee hyperbolic evolution in and unitarity of the covariantized theory, as well as the deformation's uniqueness. We show that the deformation's parameter space contains islands of absolute stability that are persistent through the entire cosmic evolution.

Criteria for resolving the cosmological singularity in infinite derivative gravity around expanding backgrounds

NASA Astrophysics Data System (ADS)

Edholm, James; Conroy, Aindriú

2017-12-01

We derive the conditions whereby null rays "defocus" within infinite derivative gravity for perturbations around an (A)dS background, and show that it is therefore possible to avoid singularities within this framework. This is in contrast to Einstein's theory of general relativity, where singularities are generated unless the null energy condition is violated. We further extend this to an (A)dS-Bianchi I background metric, and also give an example of a specific perturbation where defocusing is possible given certain conditions.

Gravitation theory - Empirical status from solar system experiments.

NASA Technical Reports Server (NTRS)

Nordtvedt, K. L., Jr.

1972-01-01

Review of historical and recent experiments which speak in favor of a post-Newtonian relativistic gravitational theory. The topics include the foundational experiments, metric theories of gravity, experiments designed to differentiate among the metric theories, and tests of Machian concepts of gravity. It is shown that the metric field for any metric theory can be specified by a series of potential terms with several parameters. It is pointed out that empirical results available up to date yield values of the parameters which are consistent with the prediction of Einstein's general relativity.

Gravity Probe-B (GP-B) Mission and Tracking, Telemetry and Control Subsystem Overview

NASA Technical Reports Server (NTRS)

Kennedy, Paul; Bell, Joseph L. (Technical Monitor)

2001-01-01

The National Aeronautics and Space Administration's (NASA) Marshall Space Flight Center (MSFC) in Huntsville, Alabama will launch the Gravity Probe B (GP-B) space experiment in the Fall of 2002. The GP-B spacecraft was developed to prove Einstein's theory of General Relativity. This paper will provide an overview of the GPB mission and will discuss the design, and test of the spacecraft Tracking, Telemetry and Control (TT&C) subsystem which incorporates NASA's latest generation standard transponder for use with the NASA Tracking and Data Relay Satellite System (TDRSS).

KIP THORNE: The Shaman of Space and Time.

PubMed

Irion, R

2000-11-24

A generation of physicists probing the extremes of gravity can trace its scientific heritage to one man: Kip Thorne of the California Institute of Technology. A recent symposium to mark Thorne's 60th birthday brought together nearly 200 experts on gravity at its strongest and strangest: the domains of black holes, colliding neutron stars, and other exotic deep-space objects. Participants came to honor their mentor, who has led the way in converting Albert Einstein's General Theory of Relativity from a purely theoretical science into an astrophysical and observational one.