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1

Weyl-Eddington-Einstein affine gravity in the context of modern cosmology  

NASA Astrophysics Data System (ADS)

We propose new models of the “affine” theory of gravity in multidimensional space-times with symmetric connections. We use and develop ideas of Weyl, Eddington, and Einstein, in particular, Einstein’s proposed method for obtaining the geometry using the Hamilton principle. More specifically, the connection coefficients are determined using a “geometric” Lagrangian that is an arbitrary function of the generalized (nonsymmetric) Ricci curvature tensor (and, possibly, other fundamental tensors) expressed in terms of the connection coefficients regarded as independent variables. Such a theory supplements the standard Einstein theory with dark energy (the cosmological constant, in the first approximation), a neutral massive (or tachyonic) meson, and massive (or tachyonic) scalar fields. These fields couple only to gravity and can generate dark matter and/or inflation. The new field masses (real or imaginary) have a geometric origin and must appear in any concrete model. The concrete choice of the Lagrangian determines further details of the theory, for example, the nature of the fields that can describe massive particles, tachyons, or even “phantoms.” In “natural” geometric theories, dark energy must also arise. The basic parameters of the theory (cosmological constant, mass, possible dimensionless constants) are theoretically indeterminate, but in the framework of modern “multiverse” ideas, this is more a virtue than a defect. We consider further extensions of the affine models and in more detail discuss approximate effective (“physical”) Lagrangians that can be applied to the cosmology of the early Universe.

Filippov, A. T.

2010-06-01

2

Comptonization in Super-Eddington Accretion Flow and Growth Timescale of Supermassive Blackholes  

E-print Network

Super-Eddington accretion onto black-holes (BHs) may occur at Ultra-Luminous compact X-ray sources in nearby galaxies, Galactic microquasars and Narrow-Line Seyfert 1 galaxies (NLS1s). Effects of electron scattering (opacity and Comptonization) and the relativistic correction (gravitational redshift and transverse Doppler effect) on the emergent spectra from super-Eddington accretion flows onto non-rotating BHs are examined for 10^{1.5} and 10^{6.5} M_sun BH masses (M_BH). With mdot [= Mdot / (L_Edd / c^2), where Mdot is the accretion rate] > 100, the spectral hardening factor via electron scattering is \\lesssim 2.3 - 6.5. Due to the mdot-sensitive hardening factor, the color temperature of the innermost radiation is not proportional to L^{0.25}, differing from the simplest standard accretion disk. The model is applied to optical--soft X-ray emission from NLS1s. We pick up one NLS1, namely PG 1448+273 with an inferred M_BH of 10^{6.4} M_sun, among the highest mdot candidates. The broadband spectral distributi...

Kawaguchi, T

2003-01-01

3

An Old Einstein -- Eddington Generalized Gravity and Modern Ideas on Branes and Cosmology  

NASA Astrophysics Data System (ADS)

We briefly discuss new models of an 'affine' theory of gravity in multidimensional space-times with symmetric connections. We use and generalize Einstein's proposal to specify the space-time geometry by use of the Hamilton principle to determine the connection coefficients from a geometric Lagrangian that is an arbitrary function of the generalized Ricci curvature tensor and of other fundamental tensors. Such a theory supplements the standard Einstein gravity with dark energy (the cosmological constant, in the first approximation), a neutral massive (or tachyonic) vector field (vecton), and massive (or tachyonic) scalar fields. These fields couple only to gravity and can generate dark matter and/or inflation. The concrete choice of the geometric Lagrangian determines further details of the theory. The most natural geometric models look similar to recently proposed brane models of cosmology usually derived from string theory.

Filippov, A. T.

2011-04-01

4

EINSTein  

NASA Astrophysics Data System (ADS)

Artificial Life techniques—specifically, multiagent-based models and evolutionary learning algorithms—provide a powerful new approach to understanding some of the fundamental processes of war. This chapter introduces a simple artificial “toy model” of combat called EINSTein. EINSTein is designed to illustrate how certain aspects of land combat can be viewed as self-organized, emergent phenomena resulting from the dynamical web of interactions among notional combatants. EINSTein's bottom-up, synthesist approach to the modeling of combat stands in stark contrast to the more traditional top-down, or reductionist, approach taken by conventional military models, and it represents a step toward developing a complex systems theoretic toolbox for identifying, exploring, and possibly exploiting self-organized, emergent collective patterns of behavior on the real battlefield. A description of the model is provided, along with examples of emergent spatial patterns and behaviors.

Ilachinski, Andrew

5

Einstein  

NSDL National Science Digital Library

From the American Museum of Natural History comes the online exhibit on the life and legacy of Albert Einstein. Students (who should probably be at least of high school age) can learn about Einstein's revolutionary thinking; his work with light, time, energy, and gravity; his thoughts on peace and war, on being a global citizen, and his legacy according to the museum. Although fairly brief, the site contains some interesting photographs and does a good job of describing the uniqueness of one of history's greatest minds.

2002-01-01

6

A Science of Sig-Einstein, Inertia,  

E-print Network

12 A Science of Sig- nals: Einstein, Inertia, and the Postal System Jimena Canales What do the speed of light and inertia have in common? According to the famous physicist Arthur Eddington, who led is concerned or not," reaching all the way into the concept of inertia. In Einstein's work, the most seemingly

Canales, Jimena

7

Classical Novae as Super-Eddington Objects  

E-print Network

Several of the inconsistencies plaguing the field of novae are resolved once we consider novae to be steady state super-Eddington objects. In particular, we show that the super-Eddington shell burning state is a natural consequence of the equations of stellar structure, and that the predicted mass loss in the super-Eddington state agrees with nova observations. We also find that the transition phase of novae can be naturally explained as "stagnating" winds.

Nir J. Shaviv

2002-07-29

8

Sub-Eddington Star-Forming Regions are Super-Eddington: Momentum Driven Outflows from Supersonic Turbulence  

E-print Network

We show that the turbulent gas in the star-forming regions of galaxies is unstable to wind formation via momentum deposition by radiation pressure or other momentum sources like supernova explosions, even if the system is below the average Eddington limit. This conclusion follows from the fact that the critical momentum injection rate per unit mass for unbinding gas from a self-gravitating system is proportional to the gas surface density and that a turbulent medium presents a broad distribution of column densities to the sources. For an average Eddington ratio of = 0.1 and for turbulent Mach numbers greater than 30, we find that ~1% of the gas is ejected per dynamical timescale at velocities larger than the local escape velocity. Because of the lognormal shape of the surface density distribution, the mass loss rate is highly sensitive to the average Eddington ratio, reaching 20-40% of the gas mass per dynamical time for = 1. Implications for the efficiency of star formation in giant molecular clouds are hi...

Thompson, Todd A

2014-01-01

9

"An expedition to heal the wounds of war". The 1919 eclipse and Eddington as Quaker adventurer.  

PubMed

The 1919 eclipse expedition's confirmation of general relativity is often celebrated as a triumph of scientific internationalism. However, British scientific opinion during World War I leaned toward the permanent severance of intellectual ties with Germany. That the expedition came to be remembered as a progressive moment of internationalism was largely the result of the efforts of A. S. Eddington. A devout Quaker, Eddington imported into the scientific community the strategies being used by his coreligionists in the national dialogue: humanize the enemy through personal contact and dramatic projects that highlight the value of peace and cooperation. The essay also addresses the common misconception that Eddington's sympathy for Einstein led him intentionally to misinterpret the expedition's results. The evidence gives no reason to think that Eddington or his coworkers were anything but rigorous. Eddington's pacifism is reflected not in manipulated data but in the meaning of the expedition and the way it entered the collective memory as a celebration of international cooperation in the wake of war. PMID:12725104

Stanley, Matthew

2003-03-01

10

Comparison of the Kepler and Eddington Missions  

NASA Technical Reports Server (NTRS)

The Kepler and Eddington missions are spaceborne photometric missions with similar apertures. Both are capable of finding Earth-size extrasolar planets and both can detect p-mode oscillations in stars. The Kepler mission is optimized to find Earth-size planets in the habitability zone of Solar-like stars and does astroseismology only as incidental science. The Eddington mission appears to be optimized for astroseismology. The Kepler design provides a very large field of view, a low measurement cadence, a heliocentric orbit, and a long mission duration. The demand for a large field-of-view results in a Schmidt design with a massive corrector. However, the use of the corrector allows a 105 square degree FOV and thereby provides 15 times the number of stars at a given magnitude than does the optical design used in Eddington. Because Kepler stares at a single FOV throughout the mission, it does much less astroseismology than Eddington. Other comparisons are also discussed.

Borucki, William J.; DeVincenzi, D. (Technical Monitor)

2002-01-01

11

PHOTON FEEDBACK: SCREENING AND THE EDDINGTON LIMIT  

SciTech Connect

Bright star-forming galaxies radiate well below their Eddington limits. The value of the flux-mean opacity that mediates the radiation force onto matter is orders of magnitude smaller than the UV or optical dust opacity. On empirical grounds, it is shown that high-redshift ULIRGs radiate at two orders of magnitude below their Eddington limits, while the local starbursters M82 and Arp 220 radiate at a few percent of their Eddington limits. A model for the radiative transfer of UV and optical light in dust-rich environments is considered. Radiation pressure on dust does not greatly affect the large-scale gas dynamics of star-forming galaxies.

Socrates, Aristotle [Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States); Sironi, Lorenzo, E-mail: socrates@ias.edu, E-mail: lsironi@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States)

2013-08-01

12

BAL QSOs AND EXTREME UFOs: THE EDDINGTON CONNECTION  

SciTech Connect

We suggest a common physical origin connecting the fast, highly ionized winds (UFOs) seen in nearby active galactic nuclei (AGNs), and the slower and less ionized winds of broad absorption line (BAL) QSOs. The primary difference is the mass-loss rate in the wind, which is ultimately determined by the rate at which mass is fed toward the central supermassive black hole (SMBH) on large scales. This is below the Eddington accretion rate in most UFOs, and slightly super-Eddington in extreme UFOs such as PG1211+143, but ranges up to {approx}10-50 times this in BAL QSOs. For UFOs this implies black hole accretion rates and wind mass-loss rates which are at most comparable to Eddington, giving fast, highly ionized winds. In contrast, BAL QSO black holes have mildly super-Eddington accretion rates, and drive winds whose mass-loss rates are significantly super-Eddington, and so are slower and less ionized. This picture correctly predicts the velocities and ionization states of the observed winds, including the recently discovered one in SDSS J1106+1939. We suggest that luminous AGNs may evolve through a sequence from BAL QSO through LoBAL to UFO-producing Seyfert or quasar as their Eddington factors drop during the decay of a bright accretion event. LoBALs correspond to a short-lived stage in which the AGN radiation pressure largely evacuates the ionization cone, but before the large-scale accretion rate has dropped to the Eddington value. We show that sub-Eddington wind rates would produce an M-{sigma} relation lying above that observed. We conclude that significant SMBH mass growth must occur in super-Eddington phases, either as BAL QSOs, extreme UFOs, or obscured from direct observation.

Zubovas, Kastytis; King, Andrew, E-mail: kastytis.zubovas@ftmc.lt [Theoretical Astrophysics Group, University of Leicester, Leicester LE1 7RH (United Kingdom)

2013-05-20

13

Masses of X-ray bursters and super-Eddington luminosities  

SciTech Connect

We show that the upper limit to the mass of X-ray bursters and the minimum of the ratio of peak luminosity to Eddington luminosity, k/sub min/, can be determined as functions of the apparent peak luminosity of a burst and the corresponding blackbody temperature. Observations of a burst recorded with the Einstein Observatory from the globular cluster Terzan 2 and of bursters recorded with the Japanses X-ray satellite Hakucho from XB 1636--536 support the conclusion that the upper limit of the mass of theses sources is approx.1 M/sub sun/, and the ratio k/sub min/ is distinctly greater than 5 for an assumed distance of 10 kpc.

Hoshi, R.

1981-07-15

14

Einstein Online  

NSDL National Science Digital Library

Einstein Online provides the user with a simple, but meticulous, approach to Einstein's Theory of Relativity. In the section 'Elementary Einstein', the theories of Special and General Relativity are explained in detail, going through concepts like Relativity, Spacetime and Space Geometry. The following section, 'Spotlights on Relativity', contains applications of both theories, from the Relativity of Simultaneity, to Gravity and Gravitational Waves, to Black Holes and Cosmology, to the Quantum realm.

2007-06-18

15

BAL QSOs and Extreme UFOs: the Eddington connection  

E-print Network

We suggest a common physical origin connecting the fast, highly ionized winds (UFOs) seen in nearby AGN, and the slower and less ionized winds of BAL QSOs. The primary difference is the mass loss rate in the wind, which is ultimately determined by the rate at which mass is fed towards the central supermassive black hole (SMBH) on large scales. This is below the Eddington accretion rate in most UFOs, and slightly super-Eddington in extreme UFOs such as PG1211+143, but ranges up to $\\sim 10-50$ times this in BAL QSOs. For UFOs this implies black hole accretion rates and wind mass loss rates which are at most comparable to Eddington, giving fast, highly-ionized winds. In contrast BAL QSO black holes have mildly super-Eddington accretion rates, and drive winds whose mass loss rates are significantly super-Eddington, and so are slower and less ionized. This picture correctly predicts the velocities and ionization states of the observed winds, including the recently-discovered one in SDSS J1106+1939. We suggest tha...

Zubovas, Kastytis

2013-01-01

16

Centenarian Einstein  

ScienceCinema

Commémoration de A.Einstein avec 4 orateurs pour honnorer sa mémoire: le prof.Weisskopf parlera de l'homme de science engagé, Daniel Amati du climat de la physique aux années 1920, Sergio Fubini de l'heure scientifique d'A.Einstein et le prof.Berob(?)

None

2011-04-25

17

Not Only Because of Theory: Dyson, Eddington and the Competing Myths of the 1919 Eclipse Expedition  

E-print Network

The 1919 Eclipse Expedition to test the light-bending prediction of General Relativity remains one of the most famous physics experiments of the 20th century. However, in recent decades it has been increasingly often alleged that the data-analysis of the expedition's leaders was faulty and biased in favor of Einstein's theory. Arthur Stanley Eddington is particularly alleged to have been prejudiced in favor of general relativity. Specifically it is claimed that some of the data, which would have favored the so-called Newtonian prediction, was thrown out on dubious grounds. This paper argues that a close examination of the views of the expedition's organizers, and of their data analysis, suggests that they had good grounds for acting as they did, and that the key people involved, in particular the astronomer Frank Watson Dyson, were not biased in favor of Einstein. It also draws attention to a modern re-analysis of the most important eclipse plates which, though overlooked until now, tends to strongly support the thesis of this paper.

Daniel Kennefick

2007-09-05

18

Not Only Because of Theory: Dyson, Eddington and the Competing Myths of the 1919 Eclipse Expedition  

E-print Network

The 1919 Eclipse Expedition to test the light-bending prediction of General Relativity remains one of the most famous physics experiments of the 20th century. However, in recent decades it has been increasingly often alleged that the data-analysis of the expedition's leaders was faulty and biased in favor of Einstein's theory. Arthur Stanley Eddington is particularly alleged to have been prejudiced in favor of general relativity. Specifically it is claimed that some of the data, which would have favored the so-called Newtonian prediction, was thrown out on dubious grounds. This paper argues that a close examination of the views of the expedition's organizers, and of their data analysis, suggests that they had good grounds for acting as they did, and that the key people involved, in particular the astronomer Frank Watson Dyson, were not biased in favor of Einstein. It also draws attention to a modern re-analysis of the most important eclipse plates which, though overlooked until now, tends to strongly support ...

Kennefick, Daniel

2007-01-01

19

Riemann-Eddington theory: Incorporating matter, degravitating the cosmological constant  

E-print Network

Here we show that, Eddington's pure affine gravity, when extended with Riemann curvature, leads to gravitational field equations that incorporate matter. This Riemanned Eddington gravity outfits a setup in which matter gravitates normally with Newton's constant but vacuum gravitates differently with an independent gravitational constant. This novel setup enables degravitation of the vacuum to observed level not by any fine-tuning but by a large hierarchy between its gravitational constant and its energy density. Remarkably, degravitation of the cosmological constant is local, causal and natural yet only empirical because the requisite degravitation condition is not predicted by the theory.

Demir, Durmus A

2014-01-01

20

Classical novae as super-Eddington steady states .  

NASA Astrophysics Data System (ADS)

The high luminosities and long decays of classical novae imply that they should be described as evolving super-Eddington (SED) steady states. We begin by describing how such states can exist--through the rise of a ``porous layer" which reduces the effective opacity, and then discuss other characteristics of these states, in particular, that a continuum driven wind will arise. We then modify the stellar structure equations to describe these characteristics. The result is a modification of the classical core-mass--luminosity relation to include the super-Eddington state. The evolution of this state through mass loss describes classical nova light curves.

Shaviv, N. J.; Dotan, C.

21

Einstein's Universe.  

ERIC Educational Resources Information Center

Presents a guide to be used by students and teachers in conjunction with a television program about Einstein. Provides general information about special and general relativity, and the universe. Includes questions for discussion after each section and a bibliography. (MA)

Carlson, Eric; Wald, Robert

1979-01-01

22

Einstein's boxes  

NASA Astrophysics Data System (ADS)

At the 1927 Solvay conference, Albert Einstein presented a thought experiment intended to demonstrate the incompleteness of the quantum mechanical description of reality. In the following years, the experiment was modified by Einstein, de Broglie, and several other commentators into a simple scenario involving the splitting in half of the wave function of a single particle in a box. This paper collects together several formulations of this thought experiment from the literature, analyzes and assesses it from the point of view of the Einstein-Bohr debates, the EPR dilemma, and Bell's theorem, and argues for "Einstein's Boxes" taking its rightful place alongside similar but historically better known quantum mechanical thought experiments such as EPR and Schrödinger's Cat.

Norsen, Travis

2005-02-01

23

The super-Eddington nature of supermassive stars  

NASA Astrophysics Data System (ADS)

Supermassive stars (SMSs) are massive hydrogen objects that slowly radiate their gravitational binding energy. Such hypothetical primordial objects may have been the seed of the massive black holes (BHs) observed at the centre of galaxies. Under the standard picture, these objects can be approximately described as n = 3 polytropes, and they are expected to shine extremely close to their Eddington luminosity. Once however one considers the porosity induced by instabilities near the Eddington limit, which give rise to super-Eddington states, the standard picture should be modified. We study the structure, evolution and mass loss of these objects. We find the following. First, the evolution of SMSs is hastened due to their increased energy release. They accelerate continuum-driven winds. If there is no rotational stabilization, these winds are insufficient to evaporate the objects such that they can collapse to form supermassive BHs, however, they do prevent SMSs from emitting a copious amount of ionizing radiation. If the SMSs are rotationally stabilized, the winds evaporate the objects until a normal sub-Eddington star remains having a mass of a few ×100 M.

Dotan, Calanit; Shaviv, Nir J.

2012-12-01

24

Instability & Mass Loss near the Eddington S. P. Owocki & N. J. Shaviv  

E-print Network

of super-Eddington luminosity. This can lead to a situation analogous to that in classical novae, wherein.g., Nova LMC 1988 #1, which was super-Eddington for about 50 days [25]). Since this is much longer than any-regulated continuum driving in super-Eddington epochs can explain the large, near tiring-limit mass loss inferred

Owocki, Stanley P.

25

Einstein's Gravity  

NSDL National Science Digital Library

In this lesson, students will read the 1919 edition of the Cosmic Times (see related resources) and respond by raising questions to be answered with further research. They will make a model of curved space to view the motion of spheres as explained by Albert Einstein's General Theory of Relativity. After presentations of their research to the class they will create an interview with Einstein. This activity is part of the Cosmic Times teachers guide and is intended to be used in conjunction with the 1919 Cosmic Times Poster.

26

Understanding accretion beyond the Eddington limit: NGC 5204 X-1  

NASA Astrophysics Data System (ADS)

It has been suggested that ULXs are in a new super-Eddington `ultraluminous' accretion state, and that they progress through a sequence of three spectral regimes with increasing accretion rate. However, our recent results (Sutton et al. 2013) indicate that inclination is also critical in determining the observed X-ray properties. These properties can broadly be explained by a massive radiatively-driven wind that emerges as the Eddington limit is exceeded, and forms a funnel around the black hole axis. Previous observations show NGC 5204 X-1 straddling the boundary between two ultraluminous regimes, marking it as a critical source in testing this scenario. Here we propose to obtain a further four 20 ks XMM-Newton EPIC observations, which will allow us to probe the validity of the proposed model.

Sutton, Andrew

2013-10-01

27

Microlensing evidence for super-Eddington disc accretion in quasars  

NASA Astrophysics Data System (ADS)

Microlensing by the stellar population of lensing galaxies provides an important opportunity to resolve the accretion disc structure spatially in strongly lensed quasars. Disc sizes estimated in this way are on average larger than the predictions of the standard Shakura-Sunyaev accretion disc model. An analysis of the observational data on microlensing variability suggests that some fraction of lensed quasars (primarily smaller-mass objects) are accreting in the super-Eddington regime. Super-Eddington accretion leads to the formation of an optically thick envelope scattering the radiation formed in the disc. This makes the apparent disc size larger and practically independent of wavelength. In the framework of our model, it is possible to make self-consistent estimates of mass accretion rates and black hole masses for the cases when both amplification-corrected fluxes and radii are available.

Abolmasov, P.; Shakura, N. I.

2012-12-01

28

Einstein Revisited  

ERIC Educational Resources Information Center

A brief description on the work and life of the great physicist scientist Albert Einstein is presented. The photoelectric paper written by him in 1905 led him to the study of fluctuations in the energy density of radiation and from there to the incomplete nature of the equipartition theorem of classical mechanics, which failed to account for…

Fine, Leonard

2005-01-01

29

Einstein's Relativity  

NSDL National Science Digital Library

These web pages contain material explaining Einstein's general and special theories of relativity. Gravity and warped spacetime are included, along with explanations of the impact on observational astronomy. This is part of Astronomy Notes, an educational resource for introductory astronomy classes.

Strobel, Nick

2004-06-13

30

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

NASA Astrophysics Data System (ADS)

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.

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

2006-12-01

31

The controversy between Alexander Friedmann and Albert Einstein about the possibility of a non-static world (German Title: Die Kontroverse zwischen Alexander Friedmann und Albert Einstein um die Möglichkeit einer nichtstatischen Welt)  

Microsoft Academic Search

Einstein's treatment of the cosmological problem as well as his unshakeable adherence to his own static solution of the complete field equations was throughout determined by Ernst Mach's idea of relativity of inertia. Friedmann, however, like Eddington, Weyl and others did not consider Mach's principle to be a part of general relativity, and so he regarded a time dependent developing

Georg Singer

2005-01-01

32

Transforming Education at Einstein  

E-print Network

of Albert Einstein College of Medicine of Yeshiva University #12;2 EinstEin : WintEr/spring 2012 Meet Our trANsfOrMiNg eDuCAtiON At eiNsteiN Education at Albert Einstein College of Medicine is undergoing the magazine for alumni, faculty, students, friends and supporters of Albert einstein College of Medicine

Yates, Andrew

33

The distance scale and Eddington efficiency of luminous quasars  

E-print Network

The relation between the central mass and quasar luminosity (M_BH \\propto L^{\\alpha}FHWM^2) links a given Eddington ratio with a value of H_0, within a cosmology with fixed (\\Omega_m,\\Omega_{\\Lambda}). We point out that because the relation is calibrated at low z using distance independent reverberation mapping to get the BLR size, the derived M_BH interestingly does not depend on H_0, while L/L_Edd is sensitive to H_0, but rather robust to changes of \\Omega_{\\Lambda} in the standard flat model. This means, e.g., that enough of extragalactic objects radiating at the Eddington limit could be used to study the global Hubble constant in a new way, bypassing the local distance ladder. The method could become practical when systematic errors in derived M_BH are understood and objects with L /leq L_Edd can be independently identified. As an illustration, if we take a sample of tranquil very luminous quasars in the redshift range 0.5 < z < 1.6, and assume that they are radiating with L_bol \\leq L_Edd, then the usual numeric factors used for calculating M_BH and L_bol would lead to the result that the Hubble constant must be larger than 45 km/s/Mpc.

P. Teerikorpi

2005-10-13

34

Einstein's aborted attempt at a dynamic steady-state universe  

E-print Network

In June 1930 Einstein visited Cambridge where he stayed with Eddington who had just shown that Einstein's supposedly static universe of 1917 was not stable. This forced Einstein to rethink his cosmology. He spent January and February 1931 at Pasadena. There, he discussed cosmology intensely with Tolman, conscious that he had to replace his original model of 1917. However, at the end of February he still had not made up his mind about an alternative. The Albert Einstein Archives of Jerusalem (AEA) hold an undated draft, handwritten by Einstein, which I date to the beginning of January 1931. In this draft Einstein hopes to have found a solution to the cosmological problem: a stationary, dynamic universe in expansion. His model was stationary because particles leaving a given volume were replaced by particles created out of the vacuum, anticipating an idea of Bondi, Gold and Hoyle published in 1948. He saw the cosmological term as energy reservoir. However, he realised that his calculations contained a numerical...

Nussbaumer, Harry

2014-01-01

35

FOREWORD: Modern Applications of Timescales Modern Applications of Timescales  

NASA Astrophysics Data System (ADS)

The development of the first atomic frequency standard by Louis Essen in the 1950s is at the origin of the adoption of the atomic definition of the SI second by the 13th General Conference on Weights and Measures in 1967 and the consequent adoption of the atomic timescale. After the short reign of ephemeris time as the world's reference timescale from 1954 until 1967, Coordinated Universal Time (UTC), synchronized to universal time UT1, appeared as the best compromise for satisfying the requests of all users. At the moment of the discussion on the adoption of an atomic timescale to replace ephemeris time, the possibility of having both an astronomical time and an atomic time to serve different purposes was discussed. In the words of Essen [1], this 'would cause endless confusion as well as involving duplication of equipment'. Forty years after the adoption of the definition of Coordinated Universal Time at the International Telecommunication Union (ITU), we are close to the moment of making a decision on whether or not to decouple UTC from its tight link to the rotation of the Earth embodied in UT1. It has been a ten-year process of discussion, mainly at the ITU with the input of the International Astronomical Union, the BIPM, the Consultative Committee for Time and Frequency and other organizations. The majority opinion supported the change based on developers and users of systems that need time synchronization to a stable and continuous reference timescale; others insist on the necessity of keeping the leap-second strategy for serving some applications or just for tradition. It is our hope that, as happened in the seventies, the most appropriate definition to serve all modern applications will be adopted with the consensus of the different sectors. The redirection of international timekeeping from astronomy to metrology can be considered the benchmark that started the era of modern timescales, all based on atomic properties. The aim of this special issue of Metrologia is to review timescales in use today, either the internationally recognized references or those adapted to some specific applications, to discuss new and future developments and to present the sometimes complex procedures for making international recommendations. We are grateful to our colleagues who, without exception, accepted our invitation to contribute to this special issue. Reference Henderson D 2005 Metrologia 42 S4-29 The pdf file contains an appendix: "Glossary of acronyms related to timescales used in this issue".

Arias, E. F.; Lewandowski, W.

2011-08-01

36

DEPENDENCE OF THE OPTICAL/ULTRAVIOLET VARIABILITY ON THE EMISSION-LINE PROPERTIES AND EDDINGTON RATIO IN ACTIVE GALACTIC NUCLEI  

SciTech Connect

The dependence of the long-term optical/UV variability on the spectral and fundamental physical parameters for radio-quiet active galactic nuclei (AGNs) is investigated. The multi-epoch-repeated photometric scanning data in the Stripe-82 region of the Sloan Digital Sky Survey (SDSS) are exploited for two comparative AGN samples (mostly quasars) selected therein: a broad-line Seyfert 1 (BLS1) type sample and a narrow-line Seyfert 1 (NLS1) type AGN sample within redshifts 0.3-0.8. Their spectral parameters are derived from the SDSS spectroscopic data. It is found that on rest-frame timescales of several years the NLS1-type AGNs show systematically smaller variability compared to the BLS1-type AGNs. In fact, the variability amplitude is found to correlate, though only moderately, with the eigenvector 1 parameters, i.e., the smaller the H{beta} linewidth, the weaker the [O III] and the stronger the Fe II emission, the smaller the variability amplitude. Moreover, an interesting inverse correlation is found between the variability and the Eddington ratio, which is perhaps more fundamental. The previously known dependence of the variability on luminosity is not significant, and the dependence on black hole mass-as claimed in recent papers and also present in our data-fades out when controlling for the Eddington ratio in the correlation analysis, though these may be partly due to the limited ranges of luminosity and black hole mass of our samples. Our result strongly supports that an accretion disk is likely to play a major role in producing the optical/UV variability.

Ai, Y. L.; Yuan, W.; Wang, J. G. [National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, P.O. Box 110, 650011 Kunming, Yunnan (China); Zhou, H. Y.; Wang, T. G.; Dong, X.-B.; Lu, H. L., E-mail: ayl@ynao.ac.c, E-mail: wmy@ynao.ac.c [Center for Astrophysics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2010-06-10

37

Albert Einstein's Methodology  

E-print Network

This paper discusses Einstein's methodology. 1. Einstein characterized his work as a theory of principle and reasoned that beyond kinematics, the 1905 heuristic relativity principle could offer new connections between non-kinematical concepts. 2. Einstein's creativity and inventiveness and process of thinking; invention or discovery. 3. Einstein considered his best friend Michele Besso as a sounding board and his class-mate from the Polytechnic Marcel Grossman, as his active partner. Yet, Einstein wrote to Arnold Sommerfeld that Grossman will never claim to be considered a co-discoverer of the Einstein-Grossmann theory. He only helped in guiding Einstein through the mathematical literature, but contributed nothing of substance to the results of the theory. Hence, Einstein neither considered Besso or Grossmann as co-discoverers of the relativity theory which he invented.

Weinstein, Galina

2012-01-01

38

Einstein Books for Adults  

NSDL National Science Digital Library

This reference list has more than 15 books and articles on Einstein that are written for adults, including biographies and some of Einstein's own writings. For each title, the author's name, publisher, and publication date are included.

39

Quantum Physics Einstein's Gravity  

E-print Network

Quantum Physics confronts Einstein's Gravity Matt Visser Physics Department Washington University Saint Louis USA Science Saturdays 13 October 2001 #12; Quantum Physics confronts Einstein's Gravity Abstract: The search for an overall master theory that is compatible both with quantum physics

Visser, Matt

40

Posing Einstein's Question: Questioning Einstein's Pose.  

ERIC Educational Resources Information Center

Discusses the events surrounding a famous picture of Albert Einstein in which he poses near a blackboard containing a tensor form of his 10 field equations for pure gravity with a question mark after it. Speculates as to the content of Einstein's lecture and the questions he might have had about the equation. (Contains over 30 references.) (WRM)

Topper, David; Vincent, Dwight E.

2000-01-01

41

Eddington-class flares and their distance from the central black hole in blazars  

NASA Astrophysics Data System (ADS)

The distance from the central engine at which the bright gamma-ray flares of blazars take place is an open question with implications on our understanding of jet formation and collimation. In some cases, pair opacity arguments suggest that the detection of sub-TeV photons points to the emission taking place beyond the ~ 0.1 pc size broad line region. Here we show that for bright flares having beaming-corrected luminosity comparable to the Eddington luminosity (Eddington-class flares), strong deceleration due to Compton drag is expected if the flare takes place inside the 1-few pc molecular torus region. This is incompatible with the highly superluminal speeds these sources exhibit, requiring that Eddington-class flares take place beyond the molecular torus. We demonstrate this in the case of the MAGIC-detected source PKS 1222+21 (Aleksicet al. 2011), a source that exhibited Eddington-class flares in 2010 (Tanaka11).

Georganopoulos, Markos; Rivas, David

2014-08-01

42

A Modeling of the Super-Eddington Luminosity in Nova Outbursts: V1974 Cygni  

E-print Network

We have modeled nova light curves exceeding the Eddington luminosity. It has been suggested that a porous structure develops in nova envelopes during the super Eddington phase and the effective opacity is much reduced for such a porous atmosphere. Based on this reduced opacity model, we have calculated envelope structures and light curves of novae. The optically thick wind model is used to simulate nova winds. We find that the photospheric luminosity and the wind mass-loss rate increase inversely proportional to the reducing factor of opacities, but the wind velocity hardly changes. We also reproduce the optical light curve of V1974 Cygni (Nova Cygni 1992) in the super-Eddington phase, which lasts 13 days from the optical peak 1.7 mag above the Eddington luminosity.

Mariko Kato; Izumi Hachisu

2005-10-02

43

A Modeling of the Super-Eddington Luminosity in Nova Outbursts: V1974 Cygni  

E-print Network

We have modeled nova light curves exceeding the Eddington luminosity. It has been suggested that a porous structure develops in nova envelopes during the super Eddington phase and the effective opacity is much reduced for such a porous atmosphere. Based on this reduced opacity model, we have calculated envelope structures and light curves of novae. The optically thick wind model is used to simulate nova winds. We find that the photospheric luminosity and the wind mass-loss rate increase inversely proportional to the reducing factor of opacities, but the wind velocity hardly changes. We also reproduce the optical light curve of V1974 Cygni (Nova Cygni 1992) in the super-Eddington phase, which lasts 13 days from the optical peak 1.7 mag above the Eddington luminosity.

Kato, M; Kato, Mariko; Hachisu, Izumi

2005-01-01

44

Einstein as Evaluator?  

ERIC Educational Resources Information Center

Like any other person, Albert Einstein was an informal evaluator, engaged in placing value on various aspects of his life, work, and the world. Based on Einstein's own statements, this paper speculates about what Einstein would have been like as a connoisseur evaluator, a conceptual evaluator, or a responsive evaluator. (Author/BW)

Caulley, Darrel N.

1982-01-01

45

Masses, beaming and Eddington ratios in ultraluminous X-ray sources  

NASA Astrophysics Data System (ADS)

I suggest that the beaming factor in bright ultraluminous X-ray sources (ULXs) varies as , where is the Eddington ratio for accretion. This is required by the observed universal Lsoft ~ T-4 relation between soft-excess luminosity and temperature, and is reasonable on general physical grounds. The beam scaling means that all observable properties of bright ULXs depend essentially only on the Eddington ratio , and that these systems vary mainly because the beaming is sensitive to the Eddington ratio. This suggests that bright ULXs are stellar-mass systems accreting at Eddington ratios of the order of 10-30, with beaming factors b >~ 0.1. Lower luminosity ULXs follow bolometric (not soft-excess) L ~ T4 correlations and probably represent sub-Eddington accretion on to black holes with masses ~10Msolar. High-mass X-ray binaries containing black holes or neutron stars and undergoing rapid thermal- or nuclear-time-scale mass transfer are excellent candidates for explaining both types. If the scaling for bright ULXs can be extrapolated to the Eddington ratios found in SS433, some objects currently identified as active galactic nuclei at modest redshifts might actually be ULXs (`pseudo-blazars'). This may explain cases where the active source does not coincide with the centre of the host galaxy.

King, A. R.

2009-02-01

46

A Century of Einstein  

NSDL National Science Digital Library

This intriguing MSNBC website addresses how Einstein's theories still affect the world we live in today. Users can view a Macromedia Flash Player-enhanced slide show summarizing Einstein's life and major accomplishments. Visitors can download the five papers from 1905, Einstein's "miracle year." Students can find a helpful interactive module discussing the principles of relativity and its importance. The website discusses Einstein's personality and beliefs and hypothesizes how Einstein might have faired in today's world. Users can learn about the questions dealing with dark matter and dark energy that scientists are still trying to understand today.

47

Decoding Intention at Sensorimotor Timescales  

PubMed Central

The ability to decode an individual's intentions in real time has long been a ‘holy grail’ of research on human volition. For example, a reliable method could be used to improve scientific study of voluntary action by allowing external probe stimuli to be delivered at different moments during development of intention and action. Several Brain Computer Interface applications have used motor imagery of repetitive actions to achieve this goal. These systems are relatively successful, but only if the intention is sustained over a period of several seconds; much longer than the timescales identified in psychophysiological studies for normal preparation for voluntary action. We have used a combination of sensorimotor rhythms and motor imagery training to decode intentions in a single-trial cued-response paradigm similar to those used in human and non-human primate motor control research. Decoding accuracy of over 0.83 was achieved with twelve participants. With this approach, we could decode intentions to move the left or right hand at sub-second timescales, both for instructed choices instructed by an external stimulus and for free choices generated intentionally by the participant. The implications for volition are considered. PMID:24523855

Salvaris, Mathew; Haggard, Patrick

2014-01-01

48

RAPID COOLING OF THE NEUTRON STAR IN THE QUIESCENT SUPER-EDDINGTON TRANSIENT XTE J1701-462  

SciTech Connect

We present Rossi X-Ray Timing Explorer and Swift observations made during the final three weeks of the 2006-2007 outburst of the super-Eddington neutron star (NS) transient XTE J1701-462, as well as Chandra and XMM-Newton observations covering the first {approx_equal}800 days of the subsequent quiescent phase. The source transitioned quickly from active accretion to quiescence, with the luminosity dropping by over 3 orders of magnitude in {approx_equal}13 days. The spectra obtained during quiescence exhibit both a thermal component, presumed to originate in emission from the NS surface, and a non-thermal component of uncertain origin, which has shown large and irregular variability. We interpret the observed decay of the inferred effective surface temperature of the NS in quiescence as the cooling of the NS crust after having been heated and brought out of thermal equilibrium with the core during the outburst. The interpretation of the data is complicated by an apparent temporary increase in temperature {approx_equal}220 days into quiescence, possibly due to an additional spurt of accretion. We derive an exponential decay timescale of {approx_equal}120{sup +30}{sub -20} days for the inferred temperature (excluding observations affected by the temporary increase). This short timescale indicates a highly conductive NS crust. Further observations are needed to confirm whether the crust is still slowly cooling or has already reached thermal equilibrium with the core at a surface temperature of {approx_equal}125 eV. The latter would imply a high equilibrium bolometric thermal luminosity of {approx_equal}5 x 10{sup 33}ergs{sup -1} for an assumed distance of 8.8 kpc.

Fridriksson, Joel K.; Lewin, Walter H. G. [Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Homan, Jeroen [MIT Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Wijnands, Rudy; Altamirano, Diego; Degenaar, Nathalie [Astronomical Institute 'Anton Pannekoek', University of Amsterdam, Science Park 904, 1098 XH, Amsterdam (Netherlands); Mendez, Mariano [Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700 AV, Groningen (Netherlands); Cackett, Edward M. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Brown, Edward F. [Department of Physics and Astronomy, National Superconducting Cyclotron Laboratory, and Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824 (United States); Belloni, Tomaso M., E-mail: joelkf@mit.ed [INAF-Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807 Merate (Italy)

2010-05-01

49

Genomic clocks and evolutionary timescales  

NASA Technical Reports Server (NTRS)

For decades, molecular clocks have helped to illuminate the evolutionary timescale of life, but now genomic data pose a challenge for time estimation methods. It is unclear how to integrate data from many genes, each potentially evolving under a different model of substitution and at a different rate. Current methods can be grouped by the way the data are handled (genes considered separately or combined into a 'supergene') and the way gene-specific rate models are applied (global versus local clock). There are advantages and disadvantages to each of these approaches, and the optimal method has not yet emerged. Fortunately, time estimates inferred using many genes or proteins have greater precision and appear to be robust to different approaches.

Blair Hedges, S.; Kumar, Sudhir

2003-01-01

50

AIDS Arises and Einstein Responds  

E-print Network

and Friends of Albert Einstein College of Medicine of Yeshiva University #12;2 EinstEin : summEr/fall 2011 The magazine for alumni, faculty, students, friends and supporters of albert einstein College of medicine.yu.edu Website: www.einstein.yu.edu Copyright © 2011 albert einstein College of medicine of Yeshiva university

Yates, Andrew

51

Einstein Homogeneous Riemannian Fibrations  

NASA Astrophysics Data System (ADS)

In this work we study the existence of homogeneous Einstein metrics on the total space of homogeneous fibrations such that the fibers are totally geodesic manifolds. We obtain the Ricci curvature of an invariant metric with totally geodesic fibers and some necessary conditions for such a metric to be Einstein in terms of Casimir operators. Some particular cases are studied, for instance, for normal base or fiber, symmetric fiber, Einstein base or fiber, for which the Einstein equations are manageable. We show the existence of new invariant Einstein metrics on homogeneous bisymmetric fibrations of maximal rank. For such spaces we describe explicitly the isotropy representation in terms subsets of roots and compute the eigenvalues of the Casimir operators of the fiber along the horizontal direction. Results for compact simply connected 4-symmetric spaces of maximal rank follow from this. Also, new invariant Einstein metrics are found on Kowalski n-symmetric spaces.

Araujo, Fatima

2009-05-01

52

On Multiple Einstein Rings  

E-print Network

A number of recent surveys for gravitational lenses have found examples of double Einstein rings. Here, we investigate analytically the occurrence of multiple Einstein rings. We prove, under very general assumptions, that at most one Einstein ring can arise from a mass distribution in a single plane lensing a single background source. Two or more Einstein rings can therefore only occur in multi-plane lensing. Surprisingly, we show that it is possible for a single source to produce more than one Einstein ring. If two point masses (or two isothermal spheres) in different planes are aligned with observer and source on the optical axis, we show that there are up to three Einstein rings. We also discuss the image morphologies for these two models if axisymmetry is broken, and give the first instances of magnification invariants in the case of two lens planes.

M. C. Werner; J. An; N. W. Evans

2008-04-23

53

STP Einstein Solids Program  

NSDL National Science Digital Library

The STP EinsteinSolids program displays the energy distribution of an Einstein solid in thermal contact with another Einstein solid. The purpose of this program is to explore the distribution of energy between two systems in thermal contact. The default state is two Einstein solids, system A and system B of with 4 particles each, and energies 10 and 2, respectively. Additional states and parameters can be specified using the Display|Switch GUI menu item. STP EinsteinSolids is part of a suite of Open Source Physics programs that model aspects of Statistical and Thermal Physics (STP). The program is distributed as a ready-to-run (compiled) Java archive. Double clicking the stp_EinsteinSolids.jar file will run the program if Java is installed on your computer. Additional programs can be found by searching ComPADRE for Open Source Physics, STP, or Statistical and Thermal Physics.

Gould, Harvey; Tobochnik, Jan; Christian, Wolfgang; Cox, Anne

2008-05-28

54

A NUMERICAL METHOD FOR STUDYING SUPER-EDDINGTON MASS TRANSFER IN DOUBLE WHITE DWARF BINARIES  

SciTech Connect

We present a numerical method for the study of double white dwarf (DWD) binary systems at the onset of super-Eddington mass transfer. We incorporate the physics of ideal inviscid hydrodynamical flow, Newtonian self-gravity, and radiation transport on a three-dimensional uniformly rotating cylindrical Eulerian grid. Care has been taken to conserve the key physical quantities such as angular momentum and energy. Our new method conserves total energy to a higher degree of accuracy than other codes that are presently being used to model mass transfer in DWD systems. We present the results of verification tests and simulate the first 20 + orbits of a binary system of mass ratio q 0.7 at the onset of dynamically unstable direct impact mass transfer. The mass transfer rate quickly exceeds the critical Eddington limit by many orders of magnitude, and thus we are unable to model a trans-Eddington phase. It appears that radiation pressure does not significantly affect the accretion flow in the highly super-Eddington regime. An optically thick common envelope forms around the binary within a few orbits. Although this envelope quickly exceeds the spatial domain of the computational grid, the fraction of the common envelope that exceeds zero gravitational binding energy is extremely small, suggesting that radiation-driven mass loss is insignificant in this regime. It remains to be seen whether simulations that capture the trans-Eddington phase of such flows will lead to the same conclusion or show that substantial material gets expelled.

Marcello, Dominic C.; Tohline, Joel E., E-mail: dmarcello@phys.lsu.edu, E-mail: tohline@phys.lsu.edu [Department of Physics and Astronomy, Louisiana State University and Agricultural and Mechanical College, 202 Nicholson Hall, Baton Rouge, LA (United States)

2012-04-01

55

Einstein's static universe  

E-print Network

Einstein's static model is the first relativistic cosmological model. The model is static, finite and of spherical spatial symmetry. I use the solution of Einstein's field equations in a homogeneous and isotropic universe -- Friedmann's equation -- to calculate the radius of curvature of the model (also known as "Einstein's universe"). Furthermore, I show, using a Newtonian analogy, the model's mostly known feature, namely, its instability under small perturbations on the state of equilibrium.

Domingos Soares

2012-03-17

56

Einstein in Time  

NSDL National Science Digital Library

This fun Web site is part of OLogy, where kids can collect virtual trading cards and create projects with them. Here, they are introduced to Einstein's scientific and humanitarian pursuits with two engaging, kid-friendly sections: Einstein in Time, a fascinating look at the major events in his life presented in a timeline and Everyday Einstein: Humanitarian, a quick overview of how he used his fame to draw attention to the things he believed in.

57

Einstein x-ray observations of cataclysmic variables  

SciTech Connect

Observations with the imaging x-ray detectors on the Einstein Observatory have led to a large increase in the number of low luminosity x-ray sources known to be associated with cataclysmic variable stars (CVs). The high sensitivity of the Einstein instrumentation has permitted study of their short timescale variability and spectra. The data are adding significantly to our knowledge of the accretion process in cataclysmic variables and forcing some revision in our ideas concerning the origin of the optical variability in these stars.

Mason, K.O.; Cordova, F.A.

1982-01-01

58

When Art Meets Einstein  

ERIC Educational Resources Information Center

This article deals with a pale blue sculpture entitled "A New World View", as an homage to the most famous scientist in modern history, Albert Einstein. It has 32 bas-relief squares composed of glass and steel that represent one aspect of the life and legacy of Albert Einstein. Images of children's faces peer out from behind the glass squares,…

Science Scope, 2006

2006-01-01

59

Einstein Educator's Guide Insert  

NSDL National Science Digital Library

This printable two-page handout includes a timeline of Einstein's life that showcases the causes he supported, along with his scientific discoveries and a copy of the letter Einstein sent to the editor of a Japanese magazine in 1952, in which he explains why he signed the letter to President Roosevelt that advocated atomic energy research.

60

Einstein for Everyone  

ScienceCinema

Young Einstein was a rebel who seemed doomed to fail. How did he overcome rejection to become the most famous scientist in history? We will discuss and explain all his theories in plain English and without math, and we will discover how Einstein's achievements impact our lives through DVDs, GPS, iPods, computers and green energy.

Piccioni, Robert

2014-06-25

61

Einstein and Boltzmann  

NASA Astrophysics Data System (ADS)

In 1916 Einstein published a remarkable paper entitled ``On the Quantum Theory of Radiation''ootnotetextA. Einstein ``On the Quantum theory of Radiation,'' Phys. Zeitschrift 18 (1917) 121. First printed in Mitteilungender Physikalischen Gesellschaft Zurich. No 18, 1916. Translated into English in Van der Waerden ``Sources of Quantum Mechanics'' (North Holland 1967) pp. 63-77. in which he obtained Planck's formula for black-body radiation by introducing a new statistical hypothesis for the emmision and absorption of electromagneic radiation based on discrete bundles of energy and momentum which are now called photons. Einstein radiation theory replaced Maxwell's classical theory by a stochastic process which, when properly interpreted, also gives well known statistics of massless particles with even spin.^2 This quantum distribution, however, was not discovered by Einstein but was communicated to him by Bose in 1924. Like Boltzmann's classical counterpart, Einstein's statistical theory leads to an irreversible approach to thermal equilibrium, but because this violates time reversal, Einstein theory can not be regarded as a fundamental theory of physical process.ootnotetextM. Nauenberg ``The evolution of radiation towards thermal equilibrium: A soluble model which illustrates the foundations of statistical mechanics,'' American Journal of Physics 72 (2004) 313 Apparently Einstein and his contemporaries were unaware of this problem, and even today this problem is ignored in contemporary discussions of Einstein's treatment of the black-body spectrum.

Nauenberg, Michael

2005-03-01

62

Explaining variance in black carbon's aging timescale  

NASA Astrophysics Data System (ADS)

The size and composition of particles containing black carbon (BC) are modified soon after emission by condensation of semi-volatile substances and coagulation with other particles, known collectively as "aging" processes. Although this change in particle properties is widely recognized, the timescale for transformation is not well constrained. In this work, we simulated aerosol aging with the particle-resolved model PartMC-MOSAIC and extracted aging timescales based on changes in particle cloud condensation nuclei (CCN). We simulated nearly 300 scenarios and, through a regression analysis, identified the key parameters driving the value of the aging timescale. We show that BC's aging timescale spans from hours to weeks, depending on the local environmental conditions and the characteristics of the fresh BC-containing particles. Although the simulations presented in this study included many processes and particle interactions, we show that 80% of the variance in the aging timescale is explained by only a few key parameters. The condensation aging timescale decreased with the flux of condensing aerosol and was shortest for the largest fresh particles, while the coagulation aging timescale decreased with the total number concentration of large (D > 100 nm), CCN-active particles and was shortest for the smallest fresh particles. Therefore, both condensation and coagulation play important roles in aging, and their relative impact depends on the particle size range.

Fierce, L.; Riemer, N.; Bond, T.

2014-07-01

63

Super-Eddington Mechanical Power of an Accreting Black Hole in M83  

E-print Network

power (11­15) make these results uncertain. In the local universe, shock-ionized gas around release energy through mechanical chan- nels (kinetic energy of jets and winds). The balance between a jet (1­3), whereas for rates approaching or exceeding the Eddington rate, we expect radiatively driven

Napp, Nils

64

PHYSICS AND REALITY. ALBERT EINSTEIN.  

E-print Network

PHYSICS AND REALITY. BY ALBERT EINSTEIN. (Translation by Jean Piccard.) § I. GENERALCONSIDERATION " of their connection. But even the concept of the Copyright, 1936, by Albert Einstein. 349 www.kostic.niu.eduHosted by Prof. M. Kostic at: Physics and Reality by Albert Einstein #12;35 ° ALBERT EINSTEIN. [J. F. I. " real

Kostic, Milivoje M.

65

Personal Recollections of Albert Einstein  

Microsoft Academic Search

My grandparents were good friends of Albert Einstein in Berlin. Later my parents also were on friendly terms with him. I had the opportunity to meet Einstein four times after my parents and I came to the United States in 1940. My parents and I, on occasion, had correspondence with Einstein and took a few photos of him. Albert Einstein

Steven Moszkowski

2005-01-01

66

The stolen brain of Einstein  

Microsoft Academic Search

Pathologist Thomas Stoltz Harvey performed an autopsy on Einstein after his death in 1955. During the autopsy Harvey removed Einstein's brain, took pictures of it and then cut it into several pieces. A lot of scientific attention has been devoted to Einstein' brain, and it still comes up once in a while. We've all heard something or other about Einstein's

Kavan Modi

2008-01-01

67

Einstein and 1905  

NASA Astrophysics Data System (ADS)

From March 17 to September 29, 1905, just over six months, Einstein wrote five papers that shifted the tectonic foundations of physics and changed the face of Nature. Three of these papers, the March paper presenting the particle of light, the May paper on Brownian motion, and the June paper on the Special Theory of Relativity are universally recognized as fundamental; however, the Brownian motion paper cannot be divorced from Einstein's April paper, A New Determination of the Dimensions of Molecules, and the September paper that gave the world its most famous equation, E = mc^2, cannot be separated from the June paper. These five papers reveal characteristics of Einstein's approach to physics.

Rigden, John

2005-05-01

68

Einstein in Wyoming.  

ERIC Educational Resources Information Center

Describes "Einstein's Adventurarium," a science center housed in an empty shopping mall in Gillette, Wyoming, created through school, business, and city-county government partnership. Describes how interactive exhibits allow exploration of life sciences, physics, and paleontology. (KDFB)

Elliot, Ian

1996-01-01

69

Once Upon Einstein  

NSDL National Science Digital Library

This book provides a description of Einstein's work through imagined scenes from his life. Topics covered include time, relativity, and quantum physics. Simple, non-mathematical analogies are used to explain the physics.

Damour, Thibault

2007-01-28

70

Einstein's Big Idea  

NSDL National Science Digital Library

This free digital library resource is tied to standards and includes downloadable video and audio segments, Flash interactives, and more.In this segment, NOVA explores the stories behind E = mc2 and relates how Einstein came to his startling conclusion that mass and energy are two forms of the same thing. A brief biography is given along with Einsteins achievements, and his discoveries about energy, mass, special relativity, and atoms.

2005-11-11

71

Albert Einstein Cancer Center  

Cancer.gov

The Albert Einstein College of Medicine at Yeshiva University was founded in 1955. In 1971, the Albert Einstein Cancer Center (AECC) was established at the medical school and in 1972, AECC became an NCI-designated Cancer Center. AECC is located in the Chanin Research Institute. The Center’s imaging facility, new mouse facilities, and expanded research programs are housed in the newly opened Price Center for Genetic and Translational Medicine.

72

Profile: Albert Einstein  

NSDL National Science Digital Library

This online article is from the Museum's Seminars on Science, a series of distance-learning courses designed to help educators meet the new national science standards. "Profile: Albert Einstein," part of the Frontiers in Physical Science seminar, briefly covers Einstein's life and work including his Special Theory of Relativity and the paper that gave the world E=mc², his Nobel Prize in Physics, his influence yet exclusion from the Manhattan Project, and his promotion of peace and human rights.

73

2010 Einstein Fellows Chosen  

NASA Astrophysics Data System (ADS)

NASA has announced the selection of the 2010 Einstein Fellows who will conduct research related to NASA's Physics of the Cosmos program, which aims to expand our knowledge of the origin, evolution, and fate of the Universe. The Einstein Fellowship provides support to the awardees for three years, and the Fellows may pursue their research at a host university or research center of their choosing in the United States. The new Fellows will begin their programs in the fall of 2010. The new Einstein Fellows and their host institutions are listed below: * Simona Giacintucci (Smithsonian Astrophysical Observatory, Cambridge, Mass.) * Boaz Katz (Institute for Advanced Studies, Princeton, N.J.) * Matthew Kerr (Stanford University, Palo Alto, Calif.) * Matthew Kistler (California Institute of Technology, Pasadena) * Emily Levesque (University of Colorado, Boulder) * Xin Liu (Harvard, Cambridge, Mass.) * Tony Mroczkowski (University of Pennsylvania, Philadelphia) * Ryan O'Leary (University of California at Berkeley) * Dov Poznanski (Lawrence Berkeley National Laboratory. Berkeley, Calif.) * Nicolas Yunes (Massachusetts Institute of Technology, Cambridge, Mass.) The Einstein Fellowships are administered for NASA by the Chandra X-ray Center in Cambridge, Mass. Along with the Hubble and Sagan Fellowships, the Einstein Fellowships are made possible by the Astrophysics Division within NASA's Science Mission Directorate. More information on the Einstein Fellowships can be found at: http://cxc.harvard.edu/fellows/CfPfellow.2009.html

2010-02-01

74

Water renewal timescales in the Scheldt Estuary  

NASA Astrophysics Data System (ADS)

Using the concepts of the Constituent-oriented Age and Residence time Theory (CART), we compute timescales related to the water renewal in the Scheldt Estuary (The Netherlands/Belgium). Three different timescales are used to better understand and characterize the dynamics of the estuary: the age of the renewing water, the residence time and the exposure time. The residence time is the time taken by a water parcel to leave the estuary for the first time while the exposure time is the total time spent by a water parcel in the estuary including re-entries. The age of a renewing water parcel is defined as the time elapsed since it entered the estuary. The renewing water was split into three types: the water originating from the sea, the water originating from the upstream fresh tidal rivers and the water originating from the different canals and docks connected to the estuary. Every timescale is computed at any time and position by means of the finite-element, unstructured-mesh model SLIM. This results in movies of the timescale fields (shown as Supplementary material), allowing a detailed analysis of their spatial and temporal variabilities. The effect of the M2 tide and the discharge regime (winter, summer or average situation) on the timescales is also investigated. Tidally-averaged timescales vary little over the width of the estuary and hence exhibit a virtually one-dimensional behaviour. However, around these average values, the timescales can vary hugely over a tidal cycle, with amplitudes that significantly depend on the space coordinates. The reason thereof has yet to be elucidated. These results underscore the need for two- or three-dimensional models with high temporal resolution for investigating the dynamics of the Scheldt Estuary.

de Brye, Benjamin; de Brauwere, Anouk; Gourgue, Olivier; Delhez, Eric J. M.; Deleersnijder, Eric

2012-06-01

75

Millisecond Timescale Synchrony among Hippocampal Neurons.  

PubMed

Inhibitory neurons in cortical circuits play critical roles in composing spike timing and oscillatory patterns in neuronal activity. These roles in turn require coherent activation of interneurons at different timescales. To investigate how the local circuitry provides for these activities, we applied resampled cross-correlation analyses to large-scale recordings of neuronal populations in the cornu ammonis 1 (CA1) and CA3 regions of the hippocampus of freely moving rats. Significant counts in the cross-correlation of cell pairs, relative to jittered surrogate spike-trains, allowed us to identify the effective couplings between neurons in CA1 and CA3 hippocampal regions on the timescale of milliseconds. In addition to putative excitatory and inhibitory monosynaptic connections, we uncovered prominent millisecond timescale synchrony between cell pairs, observed as peaks in the central 0 ms bin of cross-correlograms. This millisecond timescale synchrony appeared to be independent of network state, excitatory input, and ? oscillations. Moreover, it was frequently observed between cells of differing putative interneuronal type, arguing against gap junctions as the sole underlying source. Our observations corroborate recent in vitro findings suggesting that inhibition alone is sufficient to synchronize interneurons at such fast timescales. Moreover, we show that this synchronous spiking may cause stronger inhibition and rebound spiking in target neurons, pointing toward a potential function for millisecond synchrony of interneurons in shaping and affecting timing in pyramidal populations within and downstream from the circuit. PMID:25378164

Diba, Kamran; Amarasingham, Asohan; Mizuseki, Kenji; Buzsáki, György

2014-11-01

76

Extreme ULXs: super-Eddington accretors, or intermediate-mass black holes?  

NASA Astrophysics Data System (ADS)

Ultraluminous X-ray sources (ULXs) with luminosities up to 2 imes 10(40) erg s(-1) are now regarded as likely super-Eddington accretors powered by stellar mass black holes, and those above 10(41) erg s(-1) may be good intermediate-mass black hole (IMBH) candidates. However, the few objects lying between these ranges have an uncertain nature, and remain poorly studied. Here, we propose a new deep observation of one such object located within 20 Mpc. We will use the high quality EPIC data to determine whether its spectrum shows the characteristic signatures of the ultraluminous state, indicative of super-Eddington accretion onto large stellar black holes, or whether it appears consistent with the hard power-law spectra and > 10% fractional variability of an IMBH in the hard state.

Pintore, Fabio

2013-10-01

77

The Theory of Steady State Super-Eddington Winds and its Application to Novae  

E-print Network

We present a model for steady state winds of systems with super-Eddington luminosities. These radiatively driven winds are expected to be optically thick and clumpy as they arise from an instability driven porous atmosphere. The model is then applied to derive the mass loss observed in bright classical novae. The main results are: 1) A general relation between the mass loss rate and the total luminosity in super-Eddington systems. 2) A quantitative agreement between the observed luminosity evolution which is used to predict both the mass loss and temperature evolution, and their observations. 3) An agreement between the predicted average integrated mass loss of novae as a function of WD mass and its observations. 4) A natural explanation for the `transition phase' of novae. 5) Agreement with eta Carinae which was used to double check the theory. The prediction for the mass shed in the star's great eruption agrees with observations to within the measurement error.

Nir J. Shaviv

2000-08-30

78

Fixing Einstein's equations  

E-print Network

Einstein's equations for general relativity, when viewed as a dynamical system for evolving initial data, have a serious flaw: they cannot be proven to be well-posed (except in special coordinates). That is, they do not produce unique solutions that depend smoothly on the initial data. To remedy this failing, there has been widespread interest recently in reformulating Einstein's theory as a hyperbolic system of differential equations. The physical and geometrical content of the original theory remain unchanged, but dynamical evolution is made sound. Here we present a new hyperbolic formulation in terms of $g_{ij}$, $K_{ij}$, and $\\bGam_{kij}$ that is strikingly close to the space-plus-time (``3+1'') form of Einstein's original equations. Indeed, the familiarity of its constituents make the existence of this formulation all the more unexpected. This is the most economical first-order symmetrizable hyperbolic formulation presently known to us that has only physical characteristic speeds, either zero or the speed of light, for all (non-matter) variables. This system clarifies the relationships between Einstein's original equations and the Einstein-Ricci and Frittelli-Reula hyperbolic formulations of general relativity and establishes links to other hyperbolic formulations.

Arlen Anderson; James W. York, Jr

1999-01-07

79

Mysticism and Marxism: A.S. Eddington, Chapman Cohen, and Political Engagement Through Science Popularization  

Microsoft Academic Search

This paper argues that that political context of British science popularization in the inter-war period was intimately tied\\u000a to contemporary debates about religion and science. A leading science popularizer, the Quaker astronomer A.S. Eddington, and\\u000a one of his opponents, the materialist Chapman Cohen, are examined in detail to show the intertwined nature of science, philosophy,\\u000a religion, and politics.

Matthew Stanley

2008-01-01

80

A Super-Eddington Wind Scenario for the Progenitors of Type Ia Supernovae  

NASA Astrophysics Data System (ADS)

The accretion of hydrogen-rich material on to carbon-oxygen white dwarfs (CO WDs) is crucial for understanding Type Ia supernova (SN Ia) from the single-degenerate model, but this process has not been well understood due to the numerical difficulties in treating H and He flashes during the accretion. For CO WD masses from 0.5 to 1.378 M ? and accretion rates in the range from 10-8 to 10-5 M ? yr-1, we simulated the accretion of solar-composition material on to CO WDs using the state-of-the-art stellar evolution code of MESA. For comparison with steady-state models, we first ignored the contribution from nuclear burning to the luminosity when determining the Eddington accretion rate, and found that the properties of H burning in our accreting CO WD models are similar to those from the steady-state models, except that the critical accretion rates at which the WDs turn into red giants or H-shell flashes occur on their surfaces are slightly higher than those from the steady-state models. However, the super-Eddington wind is triggered at much lower accretion rates than previously thought, when the contribution of nuclear burning to the total luminosity is included. This super-Eddington wind naturally prevents the CO WDs with high accretion rates from becoming red giants, thus presenting an alternative to the optically thick wind proposed by Hachisu et al. Furthermore, the super-Eddington wind works in low-metallicity environments, which may explain SNe Ia observed at high redshifts.

Ma, Xin; Chen, Xuefei; Chen, Hai-liang; Denissenkov, Pavel A.; Han, Zhanwen

2013-12-01

81

The luminosity function of quasars in a merger model with allowance for the Eddington limit  

NASA Astrophysics Data System (ADS)

The role of the Eddington luminosity in a model of activity proposed earlier (Katz and Kontorovich 1990a,b, 1991) based on momentum compensation during galaxy mergers (Toomre 1972) is discussed. In spite of the fundamental dependence of the probability of merging on galaxy mass, this quantity is nearly constant, supporting the consistency obtained earlier between the observed mass functions for galaxies and the luminosity functions for quasars in a merger model.

Kontorovich, V. M.; Krivitskii, D. S.

1995-09-01

82

Inflationary tensor perturbation in Eddington-inspired Born-Infeld gravity  

NASA Astrophysics Data System (ADS)

We investigate the tensor perturbation in the inflation model driven by a massive scalar field in Eddington-inspired Born-Infeld gravity. For short-wavelength modes, the perturbation feature is very similar to that of the usual chaotic inflation. For long-wavelength modes, the perturbation exhibits a peculiar rise in the power spectrum which may leave a signature in the cosmic microwave background radiation.

Cho, Inyong; Kim, Hyeong-Chan

2014-07-01

83

Short Timescale Coronal Variability in Capella  

E-print Network

We analyze 205 ks of imaging data of the active binary, Capella, obtained with the Chandra High Resolution Camera Imager (HRC-I) to determine whether Capella shows any variability at timescales < 50 ks. We find that a clear signal for variability is present for timescales < 20 ks, and that the light curves show evidence for excess fluctuation over that expected from a purely Poisson process. This overdispersion is consistent with variability at the 2-7% level, and suggests that the coronae on the binary components of Capella are composed of low-density plasma and low-lying loops.

Vinay L. Kashyap; Jennifer Posson-Brown

2007-09-19

84

NOVA: Einstein's Big Idea  

NSDL National Science Digital Library

It is hard to overestimate the importance of Albert Einstein's equation, "Energy equals mass times the speed of light squared." A recent special from NOVA explores many different facets of the lasting and pervasive effects of this revolutionary statement. The website was developed to provide a host of complementary resources to the actual television program, and as such, anyone with even a trace of interest in the history of science or physics will want to take a close look. The interactive features are excellent; they include 10 top physicist's explanation of the famous equation and a timeline of Einstein's life. The essays offered here are also top-notch, and they include a piece titled "Einstein the Nobody" by David Bodanis and "Relativity and the Cosmos" by Alan Lightman.

2005-01-01

85

Conversations With Albert Einstein. II  

ERIC Educational Resources Information Center

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)

Shankland, R. S.

1973-01-01

86

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

NASA Astrophysics Data System (ADS)

'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 reader

Ehlers, Jürgen

2007-10-01

87

Eye on Einstein  

NSDL National Science Digital Library

This OLogy activity challenges students to find nine inventions that Einstein's ideas helped to create. The activity begins with an illustration of Al's Junk Shop. Mixed in with his junk are a Global Positioning System, CD player, computer, calculator, scanner, laser pointer, TV, and representations of both laser surgery and nuclear energy. After making a mental list of their nine choices, students can click to a second page to check their answers. Each invention has a rollover note about how Einstein's ideas helped pave the way for its creation. Alternately, the first page could be printed and used as a handout for an offline activity.

88

Quantum Einstein's Brownian motion  

E-print Network

Einstein's Brownian motion of a quantum particle in a classical environment is studied via virial and equipartition theorems. The effect of continuous measurement in a strongly dissipative environment is accounted for and a quantum generalization of the classical Einstein law of Brownian motion is obtained. A thermo-quantum Smoluchowski diffusion equation is derived via a generalization of the Madelung quantum hydrodynamics. The latter is applied for description of the quantum tunneling at equilibrium and stationary states as well as of the motion of an electron in metals, i.e. the Smoluchowski-Poisson problem.

R. Tsekov

2010-01-18

89

Deformed Einstein Gravity  

NASA Astrophysics Data System (ADS)

We introduce the necessary concepts for an algebraic construction of a gravity theory on noncommutative spaces. The ?-deformed diffeomorphisms are studied and a tensor calculus is defined. This leads to a deformed Einstein-Hilbert action which is invariant with respect to deformed diffeomorphisms. The dynamical variable is the vierbein field. The deformed action is a deformation of the usual Einstein-Hilbert action and reduces to it in the limit where the noncommutativity vanishes. This contribution is based on joint work with P. Aschieri, C. Blohmann, M. Dimitrijevi?, P. Schupp and J. Wess.

Meyer, Frank

2006-06-01

90

From Newton to Einstein.  

ERIC Educational Resources Information Center

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)

Ryder, L. H.

1987-01-01

91

Examining the Enigmatic Einstein  

ERIC Educational Resources Information Center

Albert Einstein is the icon of scientific genius. His is one the most recognizable faces in the history of mankind. This paper takes a cursory look at the man who is commonly perceived to be the epitome of eccentricity. We manage to sum up his salient traits which are associated with his name. The traits are based on anecdotal evidence. This…

Khoon, Koh Aik

2007-01-01

92

Einstein Books for Kids  

NSDL National Science Digital Library

This OLogy reference list has 10 kid-friendly books on physics. A short description is given for each title, along with author name and publisher. The list includes engaging biographies covering Einstein's life and contributions, collections of easy-to-complete science experiments, and illustrated looks at energy, time and space, light, and matter.

93

Einstein Archives Online  

NSDL National Science Digital Library

Officially released on the Web last week, this impressive digital archive features the writings, scholarship, and thoughts of Albert Einstein, one of the 20th century's greatest scientists. The site allows visitors to view and browse 3,000 high-quality digitized images of Einstein's writings, ranging from his travel diaries (many of which are in German) to his published and unpublished scholarly manuscripts. The online archive draws on the manuscripts held by the Albert Einstein Archives at the Hebrew University of Jerusalem, and was produced by the Jewish National & University Library's Digitization Project. Additionally, visitors have access to the archive database, which contains 43,000 records of Einstein related documents, such as his notebooks and third-party items. More casual visitors will want to visit the online gallery, which contains a selection of some of the key documents available here, such as his famous article that mentions the equation E=mc2. Overall, this is a thoroughly engaging and informative trove of digitized material on one of the world's most respected scientists.

94

Einstein Year 2005  

NSDL National Science Digital Library

Einstein Year marks the centenary of the three papers that Albert Einstein published in 1905, which of course, included the paper on photoelectric effect that led to his Nobel Prize in Physics. The primary aim of Einstein Year is "to enthuse young people, and those who influence them, about physics, whilst building a sustainable increase in public awareness of physics and its role in society." On the site, visitors can learn about the various ongoing activities being coordinated around the world, read a biography about Einstein, and check out the "Experiment" section, where users can explore physics through a number of simple and thoughtful experiments. A real highlight of the site is the "If you could teach the world just one thing about science" feature, which was conducted by the online magazine, _spiked_. The magazine asked dozens of scientists what "one thing" they would pick to teach the world about science, and their responses (including a few video clips) are posted on the site.

95

When Art Meets Einstein  

NSDL National Science Digital Library

A New World View, a composition of pale blue glass and steel, is an homage to the most famous scientist in modern history -- Albert Einstein. View this masterpiece for yourself by visiting the World Year of Physics (WYP) team's website that includes a number of extension activities to help middle school students explore their understanding and appreciation of science through art.

Society, American P.

2006-02-01

96

GROWTH OF EARLY SUPERMASSIVE BLACK HOLES AND THE HIGH-REDSHIFT EDDINGTON RATIO DISTRIBUTION  

SciTech Connect

Using a new large-scale ({approx} 0.75 Gpc){sup 3} hydrodynamic cosmological simulation, we investigate the growth rate of supermassive black holes (BHs) in the early universe (z {approx}> 4.75). Remarkably we find a clear peak in the typical Eddington ratio ({lambda}) at BH masses of (4-8) Multiplication-Sign 10{sup 7} M{sub Sun} (typically in halos of {approx}7 Multiplication-Sign 10{sup 11} to 1 Multiplication-Sign 10{sup 12} M{sub Sun }, close to their shock heating scale), independent of redshift and indicative that most BH growth occurs in the cold-flow-dominated regime. BH growth is enhanced at high-z and by and large regulated by the cosmological evolution of gas density, with {lambda} scaling simply as (1 + z){sup 3}. The peak in {lambda} is caused by the competition between increased gas density available in more massive hosts, and a decrease due to active galactic nucleus feedback that becomes effective above the shock heating halo mass scale and at high BH masses. We show that the distribution of {lambda} among both mass-selected and luminosity-selected samples is approximately lognormal. We combine these findings into a single lognormal fitting formula for the distribution of Eddington ratios as a function of (M{sub BH}, z). This formula can be used in analytic and semianalytic models for evolving BH populations, predicting BH masses of observed quasars, and, in conjunction with the observed distribution of Eddington ratios, can be used to constrain the BH mass function.

DeGraf, C.; Di Matteo, T.; Khandai, N.; Croft, R. [McWilliams Center for Cosmology, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States)

2012-08-10

97

Effective timescales of coupling within fluvial systems  

NASA Astrophysics Data System (ADS)

This paper presents a review of the coupling concept in fluvial geomorphology, based mainly on previously published work. Coupling mechanisms link the components of the fluvial system, controlling sediment transport down the system and the propagation of the effects of base-level change up the system. They can be viewed at several scales: at the local scale involving within-hillslope coupling, hillslope-to-channel coupling, and within-channels, tributary junction and reach-to-reach coupling. At larger scales, coupling can be considered as zonal coupling, between major zones of the system or as regional coupling, relating to complete drainage basins. These trends are illustrated particularly by the examples of hillslope-to-channel coupling in the Howgill Fells, northwest England, badland systems in southeast Spain, alluvial fans in Spain, USA and UAE, and base-level-induced dissection of Neogene sedimentary basins in southeast Spain. As the spatial scales increase, so do the timescales involved. Effective temporal scales relate to magnitude and frequency characteristics, recovery time and propagation time, the relative importance changing with the spatial scale. For downsystem coupling at the local scale, the first two are important, with propagation time increasing in importance in larger systems, especially in those involving upsystem coupling related to base-level change. The effective timescales range from the individual event, with a return period of decades, through decadal to century timescales for downsystem coupling, to tens to hundreds of thousands of years for the basinwide response to base-level change. The effective timescales influence the relative importance of factors controlling landform development.

Harvey, Adrian M.

2002-05-01

98

Helioseismic evidence of two solar granulation timescales  

NASA Astrophysics Data System (ADS)

The signature of two different scales of solar granulation in the power spectrum of disk integrated irradiance time series is presented. The fitted timescales for granulation (?GR1? 237~s and ?GR2? 62~s) are in good agreement with the characteristic lifetimes derived from recent image time series of the Sun's surface (Del Moro 2004); and probably linked to magnetic chromospheric structures such as bright points (Harvey et al. 1993).

Vázquez Ramió, H.; Régulo, C.; Roca Cortés, T.

2005-11-01

99

Eddington limited starbursts in the central 10pc of AGN, and the Torus in NGC1068  

E-print Network

We present results from a survey of nearby AGN using the near infrared adaptive optics integral field spectrograph SINFONI. These data enable us to probe the distribution and kinematics of the gas and stars at spatial resolutions as small as 0.085arcsec. We find strong evidence for recent but short lived starbursts residing in very dense nuclear disks. On scales of less than 10pc these would have reached Eddington-limited luminosities when active, perhaps accounting for their short duration. In addition, for NGC1068 at a resolution of 6pc, we present direct observations of molecular gas close around the AGN which we identify with the obscuring torus.

R. Davies; R. Genzel; L. Tacconi; F. Mueller Sanchez; A. Sternberg

2006-12-01

100

Geonic black holes and remnants in Eddington-inspired Born-Infeld gravity  

NASA Astrophysics Data System (ADS)

We show that electrically charged solutions within the Eddington-inspired Born-Infeld theory of gravity replace the central singularity by a wormhole supported by the electric field. As a result, the total energy associated with the electric field is finite and similar to that found in the Born-Infeld electromagnetic theory. When a certain charge-to-mass ratio is satisfied, in the lowest part of the mass and charge spectrum the event horizon disappears, yielding stable remnants. We argue that quantum effects in the matter sector can lower the mass of these remnants from the Planck scale down to the TeV scale.

Olmo, Gonzalo J.; Rubiera-Garcia, D.; Sanchis-Alepuz, Helios

2014-03-01

101

Massive Stars Near the Eddington Limit: Mass Loss and Envelope Inflation  

NASA Astrophysics Data System (ADS)

When massive stars approach the Eddington limit, their outer envelopes and winds become dominated by ‘opacity peaks’, i.e. by material properties. We discuss the physical consequences, namely the formation of strong Wolf-Rayet (WR) type winds and a radial extension of the stellar envelopes. The understanding of the physical processes in this regime is of basic importance for key phases of stellar evolution, such as the WR and LBV stage, and thus for questions on how massive stars evolve and how they end their lives.

Gräfener, G.; Vink, J. S.; Owocki, S. P.

2012-12-01

102

Compact binary coalescence and the science case for Einstein Telescope  

E-print Network

Einstein Telescope (ET) is a possible third generation ground-based gravitational wave observatory for which a design study is currently being carried out. A brief (and non-exhaustive) overview is given of ET's projected capabilities regarding astrophysics and cosmology through observations of inspiraling and coalescing compact binaries. In particular, ET would give us unprecedented insight into the mass function of neutron stars and black holes, the internal structure of neutron stars, the evolution of coalescence rates over cosmological timescales, and the geometry and dynamics of the Universe as a whole.

Chris Van Den Broeck

2010-03-06

103

Einstein's Zurich colloquium  

NASA Astrophysics Data System (ADS)

Einstein freely took upon himself a weekly evening colloquium in physics. The meetings were open to all interested people, including students, and were organized around reports of new work and discoveries in pyhsics. In point of fact, Einstein simply revived the custom he had himself established in 1909-1910, his first Zurich period. Here I shall focus on the 1912-1914 colloquia, which were important for the international community of physicists, because of the reputation of their leader. The information about the colloquium meetings is, unfortunately, scanty and allows but a patchy reconstruction based on scattered facts and a few eyewitness accounts. Documents are of primary importance in such circumstances. Here is one of them.

Yavelov, Boris

104

Einstein's Real "biggest Blunder"  

NASA Astrophysics Data System (ADS)

Albert Einstein's real "biggest blunder" was not the 1917 introduction into his gravitational field equations of a cosmological constant term ?, rather was his failure in 1916 to distinguish between the entirely different concepts of active gravitational mass and passive gravitational mass. Had he made the distinction, and followed David Hilbert's lead in deriving field equations from a variational principle, he might have discovered a true (not a cut and paste) Einstein-Rosen bridge and a cosmological model that would have allowed him to predict, long before such phenomena were imagined by others, inflation, a big bounce (not a big bang), an accelerating expansion of the universe, dark matter, and the existence of cosmic voids, walls, filaments and nodes.

Ellis, Homer G.

2012-10-01

105

Einstein@Home  

NSDL National Science Digital Library

Bruce Allen developed this World Year of Physics 2005 project for the Laser Interferometer Gravitational Wave Observatory (LIGO) Scientific Collaboration to recruit Internet users to help determine whether gravitational wave exist. "Einstein@Home is a program that uses your computer's idle time to search for spinning neutron stars (also called pulsars) using data from the LIGO and GEO gravitational wave detectors." Users need only a computer with a fast connection to the Internet and the Einstein@Home screensaver. After learning about the program's rules and policies, visitors can create an account and download the necessary components. The website offers a user profile zone where visitors can share information and opinions as well as links to news stories about the project.

106

Einstein-Maxwell breathers  

Microsoft Academic Search

We present a family of exact solutions of the Einstein-Maxwell equations, obtained from a Bianchi-type VI vacuum seed metric using Alekseev's inverse scattering method, which generalizes the `breather-like' vacuum solution recently obtained by Belinsky. We show that, for a range of values of two of the parameters characterizing this family, the spacetimes represent two electrogravitational plane waves emanating from an

Alexander Garate; Reinaldo J. Gleiser

1995-01-01

107

From Antiquity to Einstein  

NSDL National Science Digital Library

These online notes outline the history of Western thought on cosmology and the structure of space and time. Included is an introduction to the scientific method and large numbers, astronomy, Newton's laws, and the aspects of electricity and magnetism and optics that lead to 20th century physics. The final sections cover special and general relativity, and their impact on astronomy and cosmology. Important contributions by the Babylonians, the Egyptians, the Greeks, Ptomely, Copernicus, Kepler, Galileo, Newton, and Einstein are included..

Wudka, Jose

2004-08-11

108

Was Einstein 100% right ?  

E-print Network

The confrontation between General Relativity and experimental results, notably binary pulsar data, is summarized and its significance discussed. The agreement between experiment and theory is numerically very impressive. However, some recent theoretical findings (existence of non-perturbative strong-field effects, natural cosmological attraction toward zero scalar couplings) suggest that the present agreement between Einstein's theory and experiment might be a red herring and provide new motivations for improving the experimental tests of gravity.

T. Damour

1994-12-21

109

Albert Einstein: Rebellious Wunderkind  

E-print Network

Childhood and Schooldays: Albert Einstein, and the family members seemed to have exaggerated the story of Albert who developed slowly, learned to talk late, and whose parents thought he was abnormal. These and other stories were adopted by biographers as if they really happened in the form that Albert and his sister told them. Hence biographers were inspired by them to create a mythical public image of Albert Einstein. Albert had tendency toward temper tantrums, the young impudent rebel Einstein had an impulsive and upright nature. He rebelled against authority and refused to learn by rote. He could not easily bring himself to study what did not interest him at school, especially humanistic subjects. And so his sister told the story that his Greek professor, to whom he once submitted an especially poor paper, went so far in his anger to declare that nothing would ever become of him. Albert learned subjects in advance when it came to sciences; and during the vacation of a few months from school, Albert indepen...

Weinstein, Galina

2012-01-01

110

Einstein, Bohr, and Bell  

NASA Astrophysics Data System (ADS)

The final form of quantum physics, in the particular case of wave mechanics, was established in the years 1925-1927 by Heisenberg, Schrödinger, Born and others, but the synthesis was the work of Bohr who gave an epistemological interpretation of all the technicalities built up over those years; this interpretation will be examined briefly in Chapter 10. Although Einstein acknowledged the success of quantum mechanics in atomic, molecular and solid state physics, he disagreed deeply with Bohr's interpretation. For many years, he tried to find flaws in the formulation of quantum theory as it had been more or less accepted by a large majority of physicists, but his objections were brushed away by Bohr. However, in an article published in 1935 with Podolsky and Rosen, universally known under the acronym EPR, Einstein thought he had identified a difficulty in the by then standard interpretation. Bohr's obscure, and in part beyond the point, answer showed that Einstein had hit a sensitive target. Nevertheless, until 1964, the so-called Bohr-Einstein debate stayed uniquely on a philosophical level, and it was actually forgotten by most physicists, as the few of them aware of it thought it had no practical implication. In 1964, the Northern Irish physicist John Bell realized that the assumptions contained in the EPR article could be tested experimentally. These assumptions led to inequalities, the Bell inequalities, which were in contradiction with quantum mechanical predictions: as we shall see later on, it is extremely likely that the assumptions of the EPR article are not consistent with experiment, which, on the contrary, vindicates the predictions of quantum physics. In Section 3.2, the origin of Bell's inequalities will be explained with an intuitive example, then they will be compared with the predictions of quantum theory in Section 3.3, and finally their experimental status will be reviewed in Section 3.4. The debate between Bohr and Einstein goes much beyond a simple controversy, which is after all almost eighty years old and has been settled today. In fact, the concept introduced in this debate, that of entanglement, lies at the heart of many very important developments of modern quantum physics, in particular all those linked to quantum information (Chapter 8). Moreover, we shall see that the phenomenon of non-local correlations compels us to revise in depth our space-time representation of quantum processes. These are the two reasons why a whole chapter is devoted to this debate.

Bellac, Michel Le

2014-11-01

111

THE CAMPAIGN TO TRANSFORM EINSTEIN 2 THE CAMPAIGN TO TRANSFORM EINSTEIN  

E-print Network

THE CAMPAIGN TO TRANSFORM EINSTEIN #12;2 THE CAMPAIGN TO TRANSFORM EINSTEIN #12;ALBERT EINSTEIN COLLEGE OF MEDICINE 1 F or more than five decades, Albert Einstein College of Medicine has responded: Albert Einstein grants his name to the Albert Einstein College of Medicine 1970s: Establishment

Yates, Andrew

112

Einstein Toolkit for Relativistic Astrophysics  

NASA Astrophysics Data System (ADS)

The Einstein Toolkit is a collection of software components and tools for simulating and analyzing general relativistic astrophysical systems. Such systems include gravitational wave space-times, collisions of compact objects such as black holes or neutron stars, accretion onto compact objects, core collapse supernovae and Gamma-Ray Bursts. The Einstein Toolkit builds on numerous software efforts in the numerical relativity community including CactusEinstein, Whisky, and Carpet. The Einstein Toolkit currently uses the Cactus Framework as the underlying computational infrastructure that provides large-scale parallelization, general computational components, and a model for collaborative, portable code development.

Collaborative Effort

2011-02-01

113

X-RAY OUTFLOWS AND SUPER-EDDINGTON ACCRETION IN THE ULTRALUMINOUS X-RAY SOURCE HOLMBERG IX X-1  

SciTech Connect

Studies of X-ray continuum emission and flux variability have not conclusively revealed the nature of ultraluminous X-ray sources (ULXs) at the high-luminosity end of the distribution (those with L{sub X} {>=} 10{sup 40} erg s{sup -1}). These are of particular interest because the luminosity requires either super-Eddington accretion onto a black hole of mass {approx}10 M{sub Sun} or more standard accretion onto an intermediate-mass black hole. Super-Eddington accretion models predict strong outflowing winds, making atomic absorption lines a key diagnostic of the nature of extreme ULXs. To search for such features, we have undertaken a long, 500 ks observing campaign on Holmberg IX X-1 with Suzaku. This is the most sensitive data set in the iron K bandpass for a bright, isolated ULX to date, yet we find no statistically significant atomic features in either emission or absorption; any undetected narrow features must have equivalent widths less than 15-20 eV at 99% confidence. These limits are far below the {approx}>150 eV lines expected if observed trends between mass inflow and outflow rates extend into the super-Eddington regime and in fact rule out the line strengths observed from disk winds in a variety of sub-Eddington black holes. We therefore cannot be viewing the central regions of Holmberg IX X-1 through any substantial column of material, ruling out models of spherical super-Eddington accretion. If Holmberg IX X-1 is a super-Eddington source, any associated outflow must have an anisotropic geometry. Finally, the lack of iron emission suggests that the stellar companion cannot be launching a strong wind and that Holmberg IX X-1 must primarily accrete via Roche-lobe overflow.

Walton, D. J.; Harrison, F. A. [Space Radiation Laboratory, California Institute of Technology, Pasadena, CA 91125 (United States); Miller, J. M.; Reis, R. C. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Fabian, A. C. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA (United Kingdom); Roberts, T. P. [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Middleton, M. J. [Astronomical Institute Anton Pannekoek, University of Amsterdam, Postbus 94249, NL-1090 GE Amsterdam (Netherlands)

2013-08-10

114

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

NASA Astrophysics Data System (ADS)

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.

Grundmann, Siegfried

115

Einstein and His Times  

NSDL National Science Digital Library

In this lesson, students will read about and research the major historical events that occurred throughout the year 1919. They will use different readings and articles to understand and describe what life was like during this time. In addition, the students will present their case as to whether or not Albert Einstein should be voted "Man of the Year" for 1919. This activity is from the Cosmic Times teachers guide and is intended to be used in conjunction with the 1919 Cosmic Times Poster.

116

Einstein universes stabilized  

E-print Network

The hypothesis that gravitational self-binding energy may be the source for the vacuum energy term of cosmology is studied in a Newtonian Ansatz. For spherical spaces the attractive force of gravitation and the negative pressure of the vacuum energy term form a self stabilizing system under very reasonable restrictions for the parameters, among them a characteristic coefficient \\beta of self energy. In the Weyl geometric approach to cosmological redshift, Einstein-Weyl universes with observational restrictions of the curvature parameters are dynamically stable, if \\beta is about 40 % smaller than in the exact Newton Ansatz or if the space geometry is elliptical.

Erhard Scholz

2007-10-01

117

Galileo and Einstein  

NSDL National Science Digital Library

This website provides materials for a university-level historical astronomy course. Full lecture notes are provided, along with animations and simulations to illustrate aspects of the course. Links are provided to related supporting material. The course lecture notes are extensive and focus on two revolutions in the way humanity perceives the universe. The lectures begin with a review of important contributions from early civilizations, before focusing on the paradigm shift following Galileo's discoveries. The last part of the course discusses Einstein's contributions to astronomy and develops the theory of special relativity.

Fowler, Michael

2008-08-08

118

What, Precisely, Is "Thinking"? Einstein's Answer.  

ERIC Educational Resources Information Center

Gives an analysis of how Einstein viewed "thinking," and the nature of scientific discovery, using extensive quotations from Einstein's own writings, and especially from his essay "Autobiographical Notes."

Holton, Gerald

1979-01-01

119

Planetary chaotic zone clearing: destinations and timescales  

E-print Network

We investigate the orbital evolution of particles in a planet's chaotic zone to determine their final destinations and their timescales of clearing. There are four possible final states of chaotic particles: collision with the planet, collision with the star, escape, or bounded but non-collision orbits. In our investigations, within the framework of the planar circular restricted three body problem for planet-star mass ratio $\\mu$ in the range $10^{-9}$ to $10^{-1.5}$, we find no particles hitting the star. The relative frequencies of escape and collision with the planet are not scale-free, as they depend upon the size of the planet. For planet radius $R_p\\ge0.001R_H$ where $R_H$ is the planet's Hill radius, we find that most chaotic zone particles collide with the planet for $\\mu\\lesssim10^{-5}$; particle scattering to large distances is significant only for higher mass planets. For fixed ratio $R_p/R_H$, the particle clearing timescale, $T_{cl}$, has a broken power-law dependence on $\\mu$. A shallower power...

Morrison, Sarah

2014-01-01

120

Gamma-ray burster recurrence timescales  

NASA Technical Reports Server (NTRS)

Three optical transients have been found which are associated with gamma-ray bursters (GRBs). The deduced recurrence timescale for these optical transients (tau sub opt) will depend on the minimum brightness for which a flash would be detected. A detailed analysis using all available data of tau sub opt as a function of E(gamma)/E(opt) is given. For flashes similar to those found in the Harvard archives, the best estimate of tau sub opt is 0.74 years, with a 99% confidence interval from 0.23 years to 4.7 years. It is currently unclear whether the optical transients from GRBs also give rise to gamma-ray events. One way to test this association is to measure the recurrence timescale of gamma-ray events tau sub gamma. A total of 210 gamma-ray error boxes were examined and it was found that the number of observed overlaps is not significantly different from the number expected from chance coincidence. This observation can be used to place limits on tau sub gamma for an assumed luminosity function. It was found that tau sub gamma is approx. 10 yr if bursts are monoenergetic. However, if GRBs have a power law luminosity function with a wide dynamic range, then the limit is tau sub gamma 0.5 yr. Hence, the gamma-ray data do not require tau sub gamma and tau sub opt to be different.

Schaefer, B. E.; Cline, T. L.

1984-01-01

121

Einstein and the "Crucial" Experiment  

ERIC Educational Resources Information Center

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…

Holton, Gerald

1969-01-01

122

Albert Einstein 1879-1955.  

ERIC Educational Resources Information Center

Celebrates the centennial of Einstein's birth with an eight-page pictorial biography and two special articles: (1) Einstein the catalyst; and (2) Unitary field theories. His special and general theories of relativity and his contributions to quantum physics and other topics are also presented. (HM)

Physics Today, 1979

1979-01-01

123

Einstein: The Standard of Greatness  

SciTech Connect

Einstein's seven-month performance in 1905 has no equal in the history of physics. Beginning with his revolutionary paper, completed on March 17, and continuing to September 26, Einstein wrote a total of five papers that changed the infrastructure of physics and today, a century later, these papers remain part of the tectonic bedrock of the discipline. How Einstein approached his physics and what he accomplished certainly provided the basis for his world fame. But while the What? and the How? were, and remain, of primary importance, can they explain Einstein's celebrity standing after 1922 and his iconic status today, fifty years after his death? The question remains: Why is Einstein the standard of greatness?

Rigdon, John (Washington University) [Washington University

2005-03-16

124

STP Entropy Einstein Solid Program  

NSDL National Science Digital Library

The STP Entropy Einstein Solid program calculates the entropy of two Einstein solids that can exchange energy. The purpose of this calculation is to illustrate that the entropy is a maximum at thermal equilibrium. The default system is two Einstein solids with 50 particles each and total energy E =200. STP EntropyEinsteinSolid is part of a suite of Open Source Physics programs that model aspects of Statistical and Thermal Physics (STP). The program is distributed as a ready-to-run (compiled) Java archive. Double clicking the stp_EntropyEinsteinSolid.jar file will run the program if Java is installed on your computer. Additional programs can be found by searching ComPADRE for Open Source Physics, STP, or Statistical and Thermal Physics.

Gould, Harvey; Tobochnik, Jan; Christian, Wolfgang; Cox, Anne

2009-03-13

125

Einstein Inflationary Probe (EIP)  

NASA Technical Reports Server (NTRS)

I will discuss plans to develop a concept for the Einstein Inflation Probe: a mission to detect gravity waves from inflation via the unique signature they impart to the cosmic microwave background (CMB) polarization. A sensitive CMB polarization satellite may be the only way to probe physics at the grand-unified theory (GUT) scale, exceeding by 12 orders of magnitude the energies studied at the Large Hadron Collider. A detection of gravity waves would represent a remarkable confirmation of the inflationary paradigm and set the energy scale at which inflation occurred when the universe was a fraction of a second old. Even a strong upper limit to the gravity wave amplitude would be significant, ruling out many common models of inflation, and pointing to inflation occurring at much lower energy, if at all. Measuring gravity waves via the CMB polarization will be challenging. We will undertake a comprehensive study to identify the critical scientific requirements for the mission and their derived instrumental performance requirements. At the core of the study will be an assessment of what is scientifically and experimentally optimal within the scope and purpose of the Einstein Inflation Probe.

Hinshaw, Gary

2004-01-01

126

HIGH-VELOCITY OUTFLOWS WITHOUT AGN FEEDBACK: EDDINGTON-LIMITED STAR FORMATION IN COMPACT MASSIVE GALAXIES  

SciTech Connect

We present the discovery of compact, obscured star formation in galaxies at z {approx} 0.6 that exhibit {approx}> 1000 km s{sup -1} outflows. Using optical morphologies from the Hubble Space Telescope and infrared photometry from the Wide-field Infrared Survey Explorer, we estimate star formation rate (SFR) surface densities that approach {Sigma}{sub SFR} Almost-Equal-To 3000 M{sub Sun} yr{sup -1} kpc{sup -2}, comparable to the Eddington limit from radiation pressure on dust grains. We argue that feedback associated with a compact starburst in the form of radiation pressure from massive stars and ram pressure from supernovae and stellar winds is sufficient to produce the high-velocity outflows we observe, without the need to invoke feedback from an active galactic nucleus.

Diamond-Stanic, Aleksandar M.; Moustakas, John; Coil, Alison L. [Center for Astrophysics and Space Sciences, University of California, San Diego, La Jolla, CA 92093 (United States); Tremonti, Christy A.; Sell, Paul H. [Department of Astronomy, University of Wisconsin-Madison, Madison, WI 53706 (United States); Hickox, Ryan C. [Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755 (United States); Robaina, Aday R. [Institut de Ciencies del Cosmos, University of Barcelona, 08028 Barcelona (Spain); Rudnick, Gregory H., E-mail: aleks@ucsd.edu [Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045 (United States)

2012-08-20

127

Modeling of the Super-Eddington Phase for Classical Novae: Five IUE Novae  

E-print Network

We present a light curve model for the super-Eddington luminosity phase of five classical novae observed with IUE. Optical and UV light curves are calculated based on the optically thick wind theory with a reduced effective opacity for a porous atmosphere. Fitting a model light curve with the UV 1455 \\AA light curve, we determine the white dwarf mass and distance to be (1.3 M_sun, 4.4 kpc) for V693 CrA, (1.05 M_sun, 1.8 kpc) for V1974 Cyg, (0.95 M_sun, 4.1 kpc) for V1668 Cyg, (1.0 M_sun, 2.1 kpc) for V351 Pup, and (1.0 M_sun, 4.3 kpc) for OS And.

Kato, M; Kato, Mariko; Hachisu, Izumi

2006-01-01

128

Modeling of the Super-Eddington Phase for Classical Novae: Five IUE Novae  

E-print Network

We present a light curve model for the super-Eddington luminosity phase of five classical novae observed with IUE. Optical and UV light curves are calculated based on the optically thick wind theory with a reduced effective opacity for a porous atmosphere. Fitting a model light curve with the UV 1455 \\AA light curve, we determine the white dwarf mass and distance to be (1.3 M_sun, 4.4 kpc) for V693 CrA, (1.05 M_sun, 1.8 kpc) for V1974 Cyg, (0.95 M_sun, 4.1 kpc) for V1668 Cyg, (1.0 M_sun, 2.1 kpc) for V351 Pup, and (1.0 M_sun, 4.3 kpc) for OS And.

Mariko Kato; Izumi Hachisu

2006-11-18

129

Large scale structure formation in Eddington-inspired Born-Infeld gravity  

NASA Astrophysics Data System (ADS)

We study the large scale structure formation in Eddington-inspired Born-Infeld (EiBI) gravity. It is found that the linear growth of scalar perturbations in EiBI gravity deviates from that in general relativity for modes with large wave numbers (k), but the deviation is largely suppressed with the expansion of the Universe. We investigate the integrated Sachs-Wolfe effect in EiBI gravity, and find that its effect on the angular power spectrum of the anisotropy of the cosmic microwave background is almost the same as that in the Lambda-cold dark matter (?CDM) model. We further calculate the linear matter power spectrum in EiBI gravity and compare it with that in the ?CDM model. Deviation is found on small scales (k ?0.1h Mpc-1), which can be tested in the future by observations from galaxy surveys.

Du, Xiao-Long; Yang, Ke; Meng, Xin-He; Liu, Yu-Xiao

2014-08-01

130

Hindcasting of decadal?timescale estuarine bathymetric change with a tidal?timescale model  

USGS Publications Warehouse

Hindcasting decadal-timescale bathymetric change in estuaries is prone to error due to limited data for initial conditions, boundary forcing, and calibration; computational limitations further hinder efforts. We developed and calibrated a tidal-timescale model to bathymetric change in Suisun Bay, California, over the 1867–1887 period. A general, multiple-timescale calibration ensured robustness over all timescales; two input reduction methods, the morphological hydrograph and the morphological acceleration factor, were applied at the decadal timescale. The model was calibrated to net bathymetric change in the entire basin; average error for bathymetric change over individual depth ranges was 37%. On a model cell-by-cell basis, performance for spatial amplitude correlation was poor over the majority of the domain, though spatial phase correlation was better, with 61% of the domain correctly indicated as erosional or depositional. Poor agreement was likely caused by the specification of initial bed composition, which was unknown during the 1867–1887 period. Cross-sectional bathymetric change between channels and flats, driven primarily by wind wave resuspension, was modeled with higher skill than longitudinal change, which is driven in part by gravitational circulation. The accelerated response of depth may have prevented gravitational circulation from being represented properly. As performance criteria became more stringent in a spatial sense, the error of the model increased. While these methods are useful for estimating basin-scale sedimentation changes, they may not be suitable for predicting specific locations of erosion or deposition. They do, however, provide a foundation for realistic estuarine geomorphic modeling applications.

Ganju, Neil K.; Schoellhamer, David H.; Jaffe, Bruce E.

2009-01-01

131

Fe K Line Profile in Low-Redshift Quasars: Average Shape and Eddington Ratio Dependence  

NASA Astrophysics Data System (ADS)

We analyze X-ray spectra of 43 Palomar-Green quasars observed with XMM-Newton in order to investigate their mean Fe K line profile and its dependence on physical properties. The continuum spectra of 39 objects are well reproduced by a model consisting of a power law and a blackbody modified by Galactic absorption. The spectra of the remaining four objects require an additional power-law component absorbed with a column density of ~1023 cm-2. A feature resembling an emission line at 6.4 keV, identified with an Fe K line, is detected in 33 objects. Approximately half of the sample show an absorption feature around 0.65-0.95 keV, which is due to absorption lines and edges of O VII and O VIII. We fit the entire sample simultaneously to derive average Fe line parameters by assuming a common Fe line shape. The Fe line is relatively narrow (?=0.36 keV), with a center energy of 6.48 keV and a mean equivalent width (EW) of 248 eV. By combining black hole masses estimated from the virial method and bolometric luminosities derived from full spectral energy distributions, we examine the dependence of the Fe K line profile on the Eddington ratio. As the Eddington ratio increases, the line becomes systematically stronger (EW=130-280 eV) and broader (?=0.1-0.7 keV), and peaks at higher energies (6.4-6.8 keV). This result suggests that the accretion rate onto the black hole directly influences the geometrical structure and ionization state of the accretion disk.

Inoue, Hirohiko; Terashima, Yuichi; Ho, Luis C.

2007-06-01

132

THE STAR FORMATION LAWS OF EDDINGTON-LIMITED STAR-FORMING DISKS  

SciTech Connect

Two important avenues into understanding the formation and evolution of galaxies are the Kennicutt-Schmidt (K-S) and Elmegreen-Silk (E-S) laws. These relations connect the surface densities of gas and star formation ({Sigma}{sub gas} and {Sigma}-dot{sub *}, respectively) in a galaxy. To elucidate the K-S and E-S laws for disks where {Sigma}{sub gas} {approx}> 10{sup 4} M{sub Sun} pc{sup -2}, we compute 132 Eddington-limited star-forming disk models with radii spanning tens to hundreds of parsecs. The theoretically expected slopes ( Almost-Equal-To 1 for the K-S law and Almost-Equal-To 0.5 for the E-S relation) are relatively robust to spatial averaging over the disks. However, the star formation laws exhibit a strong dependence on opacity that separates the models by the dust-to-gas ratio that may lead to the appearance of a erroneously large slope. The total infrared luminosity (L{sub TIR}) and multiple carbon monoxide (CO) line intensities were computed for each model. While L{sub TIR} can yield an estimate of the average {Sigma}-dot{sub *} that is correct to within a factor of two, the velocity-integrated CO line intensity is a poor proxy for the average {Sigma}{sub gas} for these warm and dense disks, making the CO conversion factor ({alpha}{sub CO}) all but useless. Thus, observationally derived K-S and E-S laws at these values of {Sigma}{sub gas} that uses any transition of CO will provide a poor measurement of the underlying star formation relation. Studies of the star formation laws of Eddington-limited disks will require a high-J transition of a high density molecular tracer, as well as a sample of galaxies with known metallicity estimates.

Ballantyne, D. R.; Armour, J. N.; Indergaard, J., E-mail: david.ballantyne@physics.gatech.edu [Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

2013-03-10

133

Particle acceleration timescales in relativistic shear flows  

E-print Network

We review the acceleration of energetic particles in relativistic astrophysical jets characterized by a significant velocity shear. The possible formation of power-law momentum spectra is discussed and typical acceleration timescales are determined for a variety of different conditions such as parallel and azimuthal shear flows. Special attendance is given to the analysis of parallel shear flows with either a linear decreasing or a Gaussian-type velocity profile. It is shown that in the presence of a gradual shear flow and a particle mean free path scaling with the gyroradius, synchrotron radiation losses may no longer be able to stop the acceleration once it has started to work efficiently. Finally, the relevance of shear acceleration in small- and large-scale relativistic jets is addressed.

Frank M. Rieger; Peter Duffy

2005-06-29

134

Relativistic timescale analysis suggests lunar theory revision  

NASA Technical Reports Server (NTRS)

The SI second of the atomic clock was calibrated to match the Ephemeris Time (ET) second in a mutual four year effort between the National Physical Laboratory (NPL) and the United States Naval Observatory (USNO). The ephemeris time is 'clocked' by observing the elapsed time it takes the Moon to cross two positions (usually occultation of stars relative to a position on Earth) and dividing that time span into the predicted seconds according to the lunar equations of motion. The last revision of the equations of motion was the Improved Lunar Ephemeris (ILE), which was based on E. W. Brown's lunar theory. Brown classically derived the lunar equations from a purely Newtonian gravity with no relativistic compensations. However, ET is very theory dependent and is affected by relativity, which was not included in the ILE. To investigate the relativistic effects, a new, noninertial metric for a gravitated, translationally accelerated and rotating reference frame has three sets of contributions, namely (1) Earth's velocity, (2) the static solar gravity field and (3) the centripetal acceleration from Earth's orbit. This last term can be characterized as a pseudogravitational acceleration. This metric predicts a time dilation calculated to be -0.787481 seconds in one year. The effect of this dilation would make the ET timescale run slower than had been originally determined. Interestingly, this value is within 2 percent of the average leap second insertion rate, which is the result of the divergence between International Atomic Time (TAI) and Earth's rotational time called Universal Time (UT or UTI). Because the predictions themselves are significant, regardless of the comparison to TAI and UT, the authors will be rederiving the lunar ephemeris model in the manner of Brown with the relativistic time dilation effects from the new metric to determine a revised, relativistic ephemeris timescale that could be used to determine UT free of leap second adjustments.

Deines, Steven D.; Williams, Carol A.

1995-01-01

135

Relativistic timescale analysis suggests lunar theory revision  

NASA Astrophysics Data System (ADS)

The SI second of the atomic clock was calibrated to match the Ephemeris Time (ET) second in a mutual four year effort between the National Physical Laboratory (NPL) and the United States Naval Observatory (USNO). The ephemeris time is 'clocked' by observing the elapsed time it takes the Moon to cross two positions (usually occultation of stars relative to a position on Earth) and dividing that time span into the predicted seconds according to the lunar equations of motion. The last revision of the equations of motion was the Improved Lunar Ephemeris (ILE), which was based on E. W. Brown's lunar theory. Brown classically derived the lunar equations from a purely Newtonian gravity with no relativistic compensations. However, ET is very theory dependent and is affected by relativity, which was not included in the ILE. To investigate the relativistic effects, a new, noninertial metric for a gravitated, translationally accelerated and rotating reference frame has three sets of contributions, namely (1) Earth's velocity, (2) the static solar gravity field and (3) the centripetal acceleration from Earth's orbit. This last term can be characterized as a pseudogravitational acceleration. This metric predicts a time dilation calculated to be -0.787481 seconds in one year. The effect of this dilation would make the ET timescale run slower than had been originally determined. Interestingly, this value is within 2 percent of the average leap second insertion rate, which is the result of the divergence between International Atomic Time (TAI) and Earth's rotational time called Universal Time (UT or UTI). Because the predictions themselves are significant, regardless of the comparison to TAI and UT, the authors will be rederiving the lunar ephemeris model in the manner of Brown with the relativistic time dilation effects from the new metric to determine a revised, relativistic ephemeris timescale that could be used to determine UT free of leap second adjustments.

Deines, Steven D.; Williams, Carol A.

1995-05-01

136

The Collected Papers of Albert Einstein  

E-print Network

The Collected Papers of Albert Einstein The Collected Papers of Albert Einstein is one of the most from among more than 40,000 documents contained in the personal collection of Albert Einstein now housed at the Albert Ein- stein Archives at Hebrew University,and 15,000 Ein- stein and Einstein

Landweber, Laura

137

The Einstein Fellowship 2014 Awarded by the Einstein Forum and the Daimler and Benz Foundation  

E-print Network

, FROM THE APPLICANT'S PREVIOUS WORK. Albert Einstein-Stipendium 2014 Vergeben vom Einstein Forum und derThe Einstein Fellowship 2014 Awarded by the Einstein Forum and the Daimler and Benz Foundation The Einstein Forum and the Daimler and Benz Foundation are offering a fellowship for outstanding young thinkers

Heermann, Dieter W.

138

A hierarchy of intrinsic timescales across primate cortex.  

PubMed

Specialization and hierarchy are organizing principles for primate cortex, yet there is little direct evidence for how cortical areas are specialized in the temporal domain. We measured timescales of intrinsic fluctuations in spiking activity across areas and found a hierarchical ordering, with sensory and prefrontal areas exhibiting shorter and longer timescales, respectively. On the basis of our findings, we suggest that intrinsic timescales reflect areal specialization for task-relevant computations over multiple temporal ranges. PMID:25383900

Murray, John D; Bernacchia, Alberto; Freedman, David J; Romo, Ranulfo; Wallis, Jonathan D; Cai, Xinying; Padoa-Schioppa, Camillo; Pasternak, Tatiana; Seo, Hyojung; Lee, Daeyeol; Wang, Xiao-Jing

2014-12-01

139

SHORT TIMESCALE VARIATIONS IN THE ATMOSPHERE OF ANTARES A  

SciTech Connect

We analyze three years of high-resolution spectroscopic data and find radial velocity variations with a characteristic timescale of 100 ± 6 days that are nearly sinusoidal. Simultaneous variations in line-depth ratios imply temperature variations of up to 100 K. No photometric variation is seen on a 100 day timescale. The timescale of the variation and its resonant nature suggest solar-like oscillations driven by large-scale convection.

Pugh, T.; Gray, David F., E-mail: tpugh@uwo.ca [Department of Physics and Astronomy, Western University, London, ON (Canada)

2013-11-01

140

Timescale dependent deformation of orogenic belts?  

NASA Astrophysics Data System (ADS)

The principle aim to link geodetic, paleoseismologic and geologic estimates of fault slip is to extrapolate the respective rates from one timescale to the other to finally predict the recurrence interval of large earthquakes, which threat human habitats. This approach however, is based on two often implicitly made assumptions: a uniform slip distribution through time and space and no changes of the boundary conditions during the time interval of interest. Both assumptions are often hard to verify. A recent study, which analysed an exceptionally complete record of seismic slip for the Wasatch and related faults (Basin and Range province), ranging from 10 yr to 10 Myr suggests that such a link between geodetic and geologic rates might not exist, i.e., that our records of fault displacement may depend on the timescale over which they were measured. This view derives support from results of scaled 2D sandbox experiments, as well as numerical simulations with distinct elements, both of which investigated the effect of boundary conditions such as flexure, mechanic stratigraphy and erosion on the spatio-temporal distribution of deformation within bivergent wedges. We identified three types of processes based on their distinct spatio-temporal distribution of deformation. First, incremental strain and local strain rates are very short-lived are broadly distributed within the bivergent wedge and no temporal pattern could be established. Second, footwall shortcuts and the re-activation of either internal thrusts or of the retro shear-zone are irregularly distributed in time and are thus not predictable either, but last for a longer time interval. Third, the stepwise initiation and propagation of the deformation front is very regular in time, since it depends on the thickness of the incoming layer and on its internal and basal material properties. We consider the propagation of the deformation front as an internal clock of a thrust belt, which is therefore predictable. A deformation front advance cycle requires the longest timescale. Thus, despite known and constant boundary conditions during the simulations, we found only one regular temporal pattern of deformation in a steady active bivergent-wedge. We therefore propose that the structural inventory of an orogenic belt is hierarchically ordered with respect to accumulated slip, in analogy to the discharge pattern in a drainage network. The deformation front would have the highest, a branching splay the lowest order. Since kinematic boundary conditions control deformation front advance, its timing and the related maximum magnitude of finite strain, i.e. throw on the frontal thrust are predictable. However, the number of controlling factors, such as the degree of strain softening, the orientation of faults or fluid flow and resulting cementation of faults, responsible for the reactivation of faults increases with increasing distance from the deformation front. Since it is rarely possible to determine the complete network of forces within a wedge, the reactivation of lower order structures is not predictable in time and space. Two implications for field studies may emerge: A change of the propagation of deformation can only be determined, if at least two accretion cycles are sampled. The link between geodetic, paleoseismologic and geologic fault slip estimates can only be successfully derived if the position of the investigated fault within the hierarchical order has not changed over the time interval of interest.

Hoth, S.; Friedrich, A. M.; Vietor, T.; Hoffmann-Rothe, A.; Kukowski, N.; Oncken, O.

2004-12-01

141

Symmetries of the Einstein Equations  

E-print Network

Generalized symmetries of the Einstein equations are infinitesimal transformations of the spacetime metric that formally map solutions of the Einstein equations to other solutions. The infinitesimal generators of these symmetries are assumed to be local, \\ie at a given spacetime point they are functions of the metric and an arbitrary but finite number of derivatives of the metric at the point. We classify all generalized symmetries of the vacuum Einstein equations in four spacetime dimensions and find that the only generalized symmetry transformations consist of: (i) constant scalings of the metric (ii) the infinitesimal action of generalized spacetime diffeomorphisms. Our results rule out a large class of possible ``observables'' for the gravitational field, and suggest that the vacuum Einstein equations are not integrable.

C. G. Torre; I. M. Anderson

1993-02-23

142

Einstein: The Gourmet of Creativity.  

ERIC Educational Resources Information Center

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)

Greenberg, Joel

1979-01-01

143

Video Gallery: Reflection on Einstein  

NSDL National Science Digital Library

This online video gallery is from the Museum's Seminars on Science, a series of distance-learning courses designed to help educators meet the new national science standards. Reflections on Einstein, part of the Frontiers in Physical Science seminar, is available in broadband and modem formats and with a printable PDF transcript. The video shows excerpts of a panel of seven scientists reflecting on Einstein's influence.

144

The NASA Beyond Einstein Program  

NASA Technical Reports Server (NTRS)

The Laser Interferometer Space Antenna (LISA) mission is part of NASA s Beyond Einstein program. This program seeks to answer the questions What Powered the Big Bang?, What happens at the edge of a Black Hole?, and What is Dark Energy?. LISA IS the first mission to be launched in this new program. This paper will give an overview of the Beyond Einstein program, its current status and where LISA fits in.

White, Nicholas E.

2004-01-01

145

The NASA Beyond Einstein Program  

NASA Technical Reports Server (NTRS)

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.

White, Nicholas E.

2006-01-01

146

The Einstein Slew Survey  

NASA Technical Reports Server (NTRS)

A catalog of 819 sources detected in the Einstein IPC Slew Survey of the X-ray sky is presented; 313 of the sources were not previously known as X-ray sources. Typical count rates are 0.1 IPC count/s, roughly equivalent to a flux of 3 x 10 exp -12 ergs/sq cm s. The sources have positional uncertainties of 1.2 arcmin (90 percent confidence) radius, based on a subset of 452 sources identified with previously known pointlike X-ray sources (i.e., extent less than 3 arcmin). Identifications based on a number of existing catalogs of X-ray and optical objects are proposed for 637 of the sources, 78 percent of the survey (within a 3-arcmin error radius) including 133 identifications of new X-ray sources. A public identification data base for the Slew Survey sources will be maintained at CfA, and contributions to this data base are invited.

Elvis, Martin; Plummer, David; Schachter, Jonathan; Fabbiano, G.

1992-01-01

147

The influence of nonlinearity on the timescale of volume relaxation  

NASA Astrophysics Data System (ADS)

The relationship between the timescales of volume and enthalpy relaxation has been studied extensively in the literature with differing results. Based on volume, enthalpy, and creep relaxation studies for polyetherimide, polystyrene, and selenium, a general picture was developed for the relationship between the relative timescales of different properties which was consistent with the data in the literature. According to the general picture, the timescales of different properties are similar at temperatures above the nominal value of Tg; however, the time scales diverge at temperatures below Tg with volume and creep exhibiting longer relaxation timescales compared to enthalpy. However, when the timescales are re-analyzed using the cooling rate dependence of Tg from capillary dilatometry and DSC, no divergence between the timescales of volume and enthalpy was observed, in contradiction with the general picture. It is hypothesized that the divergence in timescales observed in earlier work is due to the pronounced nonlinearity of volume relaxation compared to enthalpy relaxation. In this work, we use capillary dilatometry to test this hypothesis; in particular, we examine the effect of the magnitude of temperature down jumps on the volume relaxation timescale for polystyrene.

Badrinarayanan, Prashanth; Simon, Sindee

2007-03-01

148

The Discovery of Timescale-dependent Color Variability of Quasars  

NASA Astrophysics Data System (ADS)

Quasars are variable on timescales from days to years in UV/optical and generally appear bluer while they brighten. The physics behind the variations in fluxes and colors remains unclear. Using Sloan Digital Sky Survey g- and r-band photometric monitoring data for quasars in Stripe 82, we find that although the flux variation amplitude increases with timescale, the color variability exhibits the opposite behavior. The color variability of quasars is prominent at timescales as short as ~10 days, but gradually reduces toward timescales up to years. In other words, the variable emission at shorter timescales is bluer than that at longer timescales. This timescale dependence is clearly and consistently detected at all redshifts from z = 0 to 3.5; thus, it cannot be due to contamination to broadband photometry from emission lines that do not respond to fast continuum variations. The discovery directly rules out the possibility that simply attributes the color variability to contamination from a non-variable redder component such as the host galaxy. It cannot be interpreted as changes in global accretion rate either. The thermal accretion disk fluctuation model is favored in the sense that fluctuations in the inner, hotter region of the disk are responsible for short-term variations, while longer-term and stronger variations are expected from the larger and cooler disk region. An interesting implication is that one can use quasar variations at different timescales to probe disk emission at different radii.

Sun, Yu-Han; Wang, Jun-Xian; Chen, Xiao-Yang; Zheng, Zhen-Ya

2014-09-01

149

Is radio jet power linearly proportional to the product of central black hole mass and Eddington ratio in AGN?  

E-print Network

A model for the relation between radio jet power and the product of central black hole (BH) mass and Eddington ratio of AGN is proposed, and the model is examined with data from the literature. We find that radio jet power positively correlates but not linearly with the product of BH mass ($m$ in solar mass) and Eddington ratio ($\\lambda$), and the power law indices ($\\mu$) are significantly less than unity for relatively low accretion ($\\lambdapower assuming that the spin induced jet is gradually suppressed as the accretion rate increases. Whereas, for the high-z quasars which often show the slope $\\mu\\geq1$, a positive correlation between the radio loudness and disc luminosity is pr...

Liu, Xiang

2014-01-01

150

Comparison of inversion codes for polarized line formation in MHD simulations. I. Milne-Eddington codes  

E-print Network

Milne-Eddington (M-E) inversion codes for the radiative transfer equation are the most widely used tools to infer the magnetic field from observations of the polarization signals in photospheric and chromospheric spectral lines. Unfortunately, a comprehensive comparison between the different M-E codes available to the solar physics community is still missing, and so is a physical interpretation of their inferences. In this contribution we offer a comparison between three of those codes (VFISV, ASP/HAO, and HeLIx$^+$). These codes are used to invert synthetic Stokes profiles that were previously obtained from realistic non-grey three-dimensional magnetohydrodynamical (3D MHD) simulations. The results of the inversion are compared with each other and with those from the MHD simulations. In the first case, the M-E codes retrieve values for the magnetic field strength, inclination and line-of-sight velocity that agree with each other within $\\sigma_B \\leq 35$ (Gauss), $\\sigma_\\gamma \\leq 1.2\\deg$, and $\\sigma_{\\r...

Borrero, J M; Lagg, A; Rezaei, R; Rempel, M

2014-01-01

151

Physics at the surface of a star in Eddington-inspired Born-Infeld Gravity  

NASA Astrophysics Data System (ADS)

We study phenomena happening at the surface of a star in Eddington-inspired Born-Infeld (EiBI) gravity. The star is made of particles, which are effectively described by a polytropic fluid. The EiBI theory was known to have a pathology that singularities happen at a star surface. We suggest that the gravitational backreaction on the particles cures the problem. Strong tidal forces near the (surface) singularity modify the effective equation of state of the particles or make the surface be unstable depending on its matter contents. The geodesic deviation equations take after Hooke's law, where its frequency squared is proportional to the scalar curvature at the surface. For a positive curvature, a particle collides with a probing wall more often and increases the pressure. With the increased pressure, the surface is no longer singular. For a negative curvature, the matters around the surface experience repulsions with infinite accelerations. Therefore, the EiBI gravity is saved from the pathology of a surface singularity.

Kim, Hyeong-Chan

2014-03-01

152

A Global Three Dimensional Radiation Magneto-hydrodynamic Simulation of Super-Eddington Accretion Disks  

E-print Network

We study super-Eddington accretion flows onto black holes using a global three dimensional radiation magneto-hydrodynamical simulation. We solve the time dependent radiative transfer equation for the specific intensities to accurately calculate the angular distribution of the emitted radiation. Turbulence generated by the magneto-rotational instability provides self-consistent angular momentum transfer. The simulation reaches inflow equilibrium with an accretion rate ~220L_edd/c^2 and forms a radiation driven outflow along the rotation axis. The mechanical energy flux carried by the outflow is ~20% of the radiative energy flux. The total mass flux lost in the outflow is about 29% of the net accretion rate. The radiative luminosity of this flow is ~10L_edd. This yields a radiative efficiency ~4.5%, which is comparable to the value in a standard thin disk model. In our simulation, vertical advection of radiation caused by magnetic buoyancy transports energy faster than photon diffusion, allowing a significant f...

Jiang, Yan-Fei; Davis, Shane W

2014-01-01

153

Physics at the surface of a star in Eddington-inspired Born-Infeld gravity  

E-print Network

We study phenomena happening at the surface of a star in Eddington-inspired Born-Infeld (EiBI) gravity. The star is made of particles, which are effectively described by a polytropic fluid. The EiBI theory was known to have a pathology that singularities happen at a star surface. We suggest that the gravitational back-reaction on the particles cures the problem. Strong tidal forces near the (surface) singularity modify the effective equation of state of the particles or make the surface be unstable depending on its matter contents. The geodesic deviation equations take after the Hooke's law, where its frequency-squared is proportional to the scalar curvature at the surface. For a positive curvature, a particle collides with a probing wall more often and increases the pressure. With the increased pressure, the surface is no longer singular. For a negative curvature, the matters around the surface experience repulsions with infinite accelerations. Therefore, the EiBI gravity is saved from the pathology of surface singularity.

Hyeong-Chan Kim

2013-12-03

154

A GODUNOV METHOD FOR MULTIDIMENSIONAL RADIATION MAGNETOHYDRODYNAMICS BASED ON A VARIABLE EDDINGTON TENSOR  

SciTech Connect

We describe a numerical algorithm to integrate the equations of radiation magnetohydrodynamics in multidimensions using Godunov methods. This algorithm solves the radiation moment equations in the mixed frame, without invoking any diffusion-like approximations. The moment equations are closed using a variable Eddington tensor whose components are calculated from a formal solution of the transfer equation at a large number of angles using the method of short characteristics. We use a comprehensive test suite to verify the algorithm, including convergence tests of radiation-modified linear acoustic and magnetosonic waves, the structure of radiation-modified shocks, and two-dimensional tests of photon bubble instability and the ablation of dense clouds by an intense radiation field. These tests cover a very wide range of regimes, including both optically thick and thin flows, and ratios of the radiation to gas pressure of at least 10{sup -4}-10{sup 4}. Across most of the parameter space, we find that the method is accurate. However, the tests also reveal there are regimes where the method needs improvement, for example when both the radiation pressure and absorption opacity are very large. We suggest modifications to the algorithm that will improve the accuracy in this case. We discuss the advantages of this method over those based on flux-limited diffusion. In particular, we find that the method is not only substantially more accurate, but often no more expensive than the diffusion approximation for our intended applications.

Jiang Yanfei; Stone, James M. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Davis, Shane W. [Canadian Institute for Theoretical Astrophysics, Toronto, ON M5S3H4 (Canada)

2012-03-01

155

The bolometric luminosity of type 2 AGN from extinction-corrected [OIII]. No evidence of Eddington-limited sources  

NASA Astrophysics Data System (ADS)

Context: There have been recent claims that a significant fraction of type 2 AGN accrete close to or even above the Eddington limit. In type 2 AGN, the bolometric luminosity (L_b) is generally inferred from the [OIII] emission line luminosity (L_OIII). The key issue in estimating the bolometric luminosity in these AGN, is therefore to know the bolometric correction to be applied to L_OIII. A complication arises from the observed L_OIII being affected by extinction, most likely from dust within the narrow line region. The extinction-corrected [OIII] luminosity (L^c_OIII) is a better estimator of the nuclear luminosity than L_OIII. However, only the bolometric correction to be applied to the uncorrected L_OIII has been evaluated so far. Aims: This paper is devoted to estimating the bolometric correction C_OIII=L_b/L^c_OIII for deriving the Eddington ratios for the type 2 AGN in a sample of SDSS objects. Methods: We collected 61 sources from the literature with reliable estimates of both L^c_OIII and X-ray luminosities (L_X). To estimate C_OIII, we combined the observed correlation between L^c_OIII and LX with the X-ray bolometric correction. Results: In contrast to previous studies, we found a linear correlation between L^c_OIII and L_X. We estimated C_OIII using an earlier luminosity-dependent X-ray bolometric correction, and we found a mean value of C_OIII in the luminosity ranges log L_OIII = 38-40, 40-42, and 42-44 of 87, 142, and 454, respectively. We used it to calculate the Eddington ratio distribution of type 2 SDSS AGN at 0.3Eddington limit, contrary to previous claims.

Lamastra, A.; Bianchi, S.; Matt, G.; Perola, G. C.; Barcons, X.; Carrera, F. J.

2009-09-01

156

Super-Eddington Accretion in the Ultraluminous X-Ray Source NGC 1313 X-2: An Ephemeral Feast  

NASA Astrophysics Data System (ADS)

We investigate the X-ray spectrum, variability, and the surrounding ionized bubble of NGC 1313 X-2 to explore the physics of super-Eddington accretion. Beyond the Eddington luminosity, the accretion disk of NGC 1313 X-2 is truncated at a large radius (~50 times the innermost stable circular orbit), and displays the similar evolution track with both luminous Galactic black-hole and neutron star X-ray binaries (XRBs). In super-critical accretion, the speed of radiatively driven outflows from the inner disk is mildly relativistic. Such ultra-fast outflows would be overionized and might produce weak Fe K absorption lines, which may be detected by the coming X-ray mission Astro-H. If NGC 1313 X-2 is a massive stellar XRB, the high luminosity indicates that an ephemeral feast is held in the source. That is, the source must be accreting at a hyper-Eddington mass rate to give the super-Eddington emission over ~104-105 yr. The expansion of the surrounding bubble nebula with a velocity of ~100 km s-1 might indicate that it has existed over ~106 yr and is inflated by the radiatively driven outflows from the transient with a duty cycle of activity of ~ a few percent. Alternatively, if the surrounding bubble nebula is produced by line-driven winds, less energy is required than the radiatively driven outflow scenario, and the radius of the Strömgren radius agrees with the nebula size. Our results are in favor of the line-driven winds scenario, which can avoid the conflict between the short accretion age and the apparently much longer bubble age inferred from the expansion velocity in the nebula.

Weng, Shan-Shan; Zhang, Shuang-Nan; Zhao, Hai-Hui

2014-01-01

157

Einstein's Radiation Formula and Modifications to the Einstein Equation  

NASA Astrophysics Data System (ADS)

Einstein's radiation formula is supported by the Taylor-Hulse experiment, but its derivation is not self-consistent. Furthermore, as discovered by Einstein, his radiation formula is not compatible with his field equation. As suggested by Einstein's own remark, modifications to the source tensor are necessary. Based on the Taylor-Hulse experiment, in this paper a theory is developed within the theoretical framework of general relativity within which the radiation formula remains the same for binary stars. Concurrently, it is determined that, because of radiation, the source tensor is not zero in a vacuum. Antigravity coupling, suggested by Pauli as a possibility, is a necessary feature. In addition, it is shown that the current theory of linearized gravity is not valid for radiation.

Lo, C. Y.

1995-12-01

158

My Half Hour with Einstein  

NASA Astrophysics Data System (ADS)

"So you're studying at Princeton. Would you like to meet Einstein?" That question, during a brief two-body collision at a cocktail party, a collision that was over before I could think of an appropriate response, led—over a year later—to one of the more memorable half hours of my life. It was an elastic collision, we drifted apart, and I thought it had simply been a casual remark until a few days later when the mail brought me a carbon copy [sic] of a letter (dated "25.XII.52") from the speaker, Dr. Tilly Edinger, to Albert Einstein. Accompanying the letter to Einstein was a card that Dr. Edinger advised me to send around to Einstein's home on Mercer Street to request a meeting. (What is perhaps most truly astonishing in connection with this event is that not only do I still have that carbon copy—and the eventual letter from Mercer Street that invited me to Einstein's home—but that I was able to find both documents in my attic!)

Romer, Robert H.

2005-03-01

159

Einstein spaces as attractors for the Einstein flow  

E-print Network

In this paper we prove a global existence theorem, in the direction of cosmological expansion, for sufficiently small perturbations of a family of $n+1$-dimensional, $n \\geq 3$, spatially compact spacetimes which generalizes the $k=-1$ Friedmann--Robertson--Walker vacuum spacetime. Our results demonstrate causal geodesic completeness of the perturbed spacetimes, in the expanding direction, and show that the scale-free geometry converges towards an element in the moduli space of Einstein geometries, with a rate of decay depending on the stability properties of the Einstein geometry.

Lars Andersson; Vincent Moncrief

2009-08-06

160

Triangle Anomalies from Einstein Manifolds  

E-print Network

The triangle anomalies in conformal field theory, which can be used to determine the central charge a, correspond to the Chern-Simons couplings of gauge fields in AdS under the gauge/gravity correspondence. We present a simple geometrical formula for the Chern-Simons couplings in the case of type IIB supergravity compactified on a five-dimensional Einstein manifold X. When X is a circle bundle over del Pezzo surfaces or a toric Sasaki-Einstein manifold, we show that the gravity result is in perfect agreement with the corresponding quiver gauge theory. Our analysis reveals an interesting connection with the condensation of giant gravitons or dibaryon operators which effectively induces a rolling among Sasaki-Einstein vacua.

Sergio Benvenuti; Leopoldo A. Pando Zayas; Yuji Tachikawa

2006-01-10

161

Einstein Session of the Pontifical Academy.  

ERIC Educational Resources Information Center

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)

Science, 1980

1980-01-01

162

Reaching biological timescales with all-atom molecular dynamics simulations.  

PubMed

Molecular dynamics (MD) simulations can provide atomically detailed views of protein motions, sampling multiple timescales ranging from femtoseconds to nanoseconds on typical computing resources. The 'reach' of these computer simulations toward biologically relevant timescales (microseconds and beyond) has been improving with advances in hardware and software, as well as the development of enhanced sampling techniques. This review outlines these advances, focusing on techniques that also provide realistic, unperturbed kinetics. These longer-timescale MD simulations can provide detailed insights into the mechanisms of biological events, potentially aiding the design of pharmaceuticals. PMID:20934381

Zwier, Matthew C; Chong, Lillian T

2010-12-01

163

Einstein: Physicist, Philosopher, Humanitarian Youngstown State March 25, 2009 Albert Einstein: Physicist,  

E-print Network

Einstein: Physicist, Philosopher, Humanitarian ­ Youngstown State ­ March 25, 2009 Albert Einstein and Philosophy of Science University of Notre Dame Youngstown State University March 25, 2009 Einstein as a college student, ca. 1900 #12;Einstein: Physicist, Philosopher, Humanitarian ­ Youngstown State ­ March 25

Howard, Don

164

winter 2008 I EinstEin EINSTEINwinter 2008  

E-print Network

:Apublicationforfaculty,students,alumni,friendsandsupporters oftheAlbertEinsteinCollegeofMedicineofYeshivaUniversity. Visitusonlineatwww.aecom.yu.edu. ©2008Volume28winter 2008 I EinstEin EINSTEINwinter 2008 THE EINSTEIN EDGE TODAY'S SCIENCE... TOMORROW'S MEDICINE #12; EinstEin I winter 2008 winter 2008 I EinstEin EINSTEINCONTENTSwinter 2008 EINSTEIN

Yates, Andrew

165

Schwinger's Approach to Einstein's Gravity  

NASA Astrophysics Data System (ADS)

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.

Milton, Kim

2012-05-01

166

A Global Three-dimensional Radiation Magneto-hydrodynamic Simulation of Super-Eddington Accretion Disks  

NASA Astrophysics Data System (ADS)

We study super-Eddington accretion flows onto black holes using a global three-dimensional radiation magneto-hydrodynamical simulation. We solve the time-dependent radiative transfer equation for the specific intensities to accurately calculate the angular distribution of the emitted radiation. Turbulence generated by the magneto-rotational instability provides self-consistent angular momentum transfer. The simulation reaches inflow equilibrium with an accretion rate ~220 L Edd/c 2 and forms a radiation-driven outflow along the rotation axis. The mechanical energy flux carried by the outflow is ~20% of the radiative energy flux. The total mass flux lost in the outflow is about 29% of the net accretion rate. The radiative luminosity of this flow is ~10 L Edd. This yields a radiative efficiency ~4.5%, which is comparable to the value in a standard thin disk model. In our simulation, vertical advection of radiation caused by magnetic buoyancy transports energy faster than photon diffusion, allowing a significant fraction of the photons to escape from the surface of the disk before being advected into the black hole. We contrast our results with the lower radiative efficiencies inferred in most models, such as the slim disk model, which neglect vertical advection. Our inferred radiative efficiencies also exceed published results from previous global numerical simulations, which did not attribute a significant role to vertical advection. We briefly discuss the implications for the growth of supermassive black holes in the early universe and describe how these results provided a basis for explaining the spectrum and population statistics of ultraluminous X-ray sources.

Jiang, Yan-Fei; Stone, James M.; Davis, Shane W.

2014-12-01

167

SN 2008S: A Cool Super-Eddington Wind in a Supernova Impostor  

E-print Network

We present visual-wavelength photometry and spectroscopy of supernova SN2008S. Based on the low peak luminosity for a SN of M_R = -13.9 mag, photometric and spectral evolution unlike that of low-luminosity SNe, a late-time decline rate slower than 56Co decay, and slow outflow speeds of 600-1000 km/s, we conclude that SN2008S is not a true core-collapse SN and is probably not an electron-capture SN. Instead, we show that SN2008S more closely resembles a "SN impostor" event like SN1997bs, analogous to the giant eruptions of LBVs. Its total radiated energy was 1e47.8 ergs, and it may have ejected 0.05-0.2 Msun in the event. We discover an uncanny similarity between the spectrum of SN 2008S and that of the Galactic hypergiant IRC+10420, which is dominated by narrow H-alpha, [Ca II], and Ca II emission lines formed in an opaque wind. We propose a scenario where the vastly super-Eddington wind of SN2008S partly fails because of reduced opacity due to recombination, as suggested for IRC+10420. The range of initial masses susceptible to eruptive LBV-like mass loss was known to extend down to 20-25 Msun, but estimates for the progenitor of SN2008S (and the similar NGC300 transient) may extend this range to around 15 Msun. As such, SN2008S may have implications for the progenitor of SN1987A.

Nathan Smith; Mohan Ganeshalingam; Ryan Chornock; Alexei V. Filippenko; Weidong Li; Jeffrey M. Silverman; Thea N. Steele; Christopher V. Griffith; Niels Joubert; Nicholas Y. Lee; Thomas B. Lowe; Martin P. Mobberley; Dustin M. Winslow

2008-11-24

168

How Compact is the Stellar Mass in Eddington-Limited Starbursts?  

NASA Astrophysics Data System (ADS)

Theoretical models require strong ejective feedback to quench star formation in massive galaxies. To provide observational constraints on how this feedback process works, we have identified a sample of massive galaxies that have recently experienced a feedback-limited starburst and exhibit high-velocity, galactic-scale outflows. Our previous HST observations have shown that these galaxies are the remnants of gas-rich major mergers, and their incredibly compact optical morphologies (half-light radii ~ 100 pc) suggest that feedback from massive stars and supernovae was responsible for launching their spectacular gaseous outflows (v=500-2500 km/s). However, there is a crucial outstanding question regarding the outflow launching mechanism: how do the velocities compare to the escape velocity of the central stellar population? The current data at rest-frame V are sufficient to measure the size of the recent starburst, but we need to know how much mass is associated with this compact component in order to determine the escape velocity. Here we propose rest-frame U and rest-frame J observations for 12 extremely compact galaxies with high-velocity outflows and SFR surface densities that approach the Eddington limit. We will use spatially resolved U-V and V-J colors in tandem with the well-sampled, spatially integrated SED to determine the fraction of the stellar mass that is associated with the compact starburst. This will determine whether (1) the launching mechanism exceeds the escape velocity by a large factor or (2) the observed outflow velocity is comparable to the escape velocity, implying that these are the most compact galaxies ever observed by HST.

Diamond-Stanic, Aleksandar

2014-10-01

169

Homogeneous Einstein metrics on SU(n)  

NASA Astrophysics Data System (ADS)

It is known that every compact simple Lie group admits a bi-invariant homogeneous Einstein metric. In this paper we use two ansatz to probe the existence of additional inequivalent Einstein metrics on the Lie group SU(n) for arbitrary n. We provide an explicit construction of (2k+1) inequivalent Einstein metrics on SU(2k) and 2k inequivalent Einstein metrics on SU(2k+1).

Mujtaba, A. H.

2012-05-01

170

Homogeneous Einstein metrics on SU(n)  

E-print Network

It is known that every compact simple Lie group admits a bi-invariant homogeneous Einstein metric. In this paper we use two ansatz to probe the existence of additional inequivalent Einstein metrics on the Lie group SU (n) for arbitrary n. We provide an explicit construction of (2k+1) inequivalent Einstein metrics on SU (2k) and 2k inequivalent Einstein metrics on SU (2k + 1).

Abid H. Mujtaba

2011-10-10

171

Einstein Solid Temperature Demon Worksheet and Model  

NSDL National Science Digital Library

A worksheet that considers an Einstein solid in contact with a temperature demon (a single oscillator thermometer that exchanges energy with the Einstein solid). The combined solid-demon system is isolated. The number of energy units in this system can be adjusted by editing the field in the main display. All of this energy is originally in the Einstein solid, but after interaction starts it is shared between the demon and the Einstein solid.

Wheaton, Spencer

2013-08-16

172

Galileo and Einstein: Physics Flashlets  

NSDL National Science Digital Library

This is a collection of Flash animations developed to support a course in introductory historical astronomy. The "Flashlets" are presented sequentially, beginning with early Greek science and Galilean motion. The series progresses through the Kepler's and Newton's Laws and culminates in Einstein's theory of special relativity and time dilation. This collection is part of a larger set of curriculum materials developed at the University of Virginia for the course "Galileo and Einstein". See Related Materials for a link to the full index, which includes lecture notes, Java simulations, and historical excerpts.

Fowler, Michael

2008-07-29

173

First strike Sixty years ago, Albert Einstein  

E-print Network

First strike Sixty years ago, Albert Einstein said that the existence of nuclear weapons would physicists, including Einstein, have argued that the first use of nuclear weapons can never again. Einstein's hope of new thinking in a nuclear world may be too much to expect, but I hope

Rhoads, James

174

Albert Einstein: Relativity, War, Daniel J. Kevles  

E-print Network

Albert Einstein: Relativity, War, and Fame Daniel J. Kevles In 1922, Princeton University Press published Albert Einstein's The Meaning of Relativity, a popularization of his theory that has remained as succes- sive editions of his writings appear. Albert Einstein burst upon the world of physics in 1905

Landweber, Laura

175

100 years since Einstein's less known revolution  

E-print Network

) to their microscopic components and interactions with the environment. Albert Einstein made crucial contributions of semi-conductors and the computer revolution that followed. It is amazing that Albert Einstein when he1 100 years since Einstein's less known revolution: From the pollen dance to atoms and back

Andelman, David

176

The General Introduction of Einstein meets Magritte  

E-print Network

long and exhausting and the press were doing all they could to get Albert Einstein and Ren´e MagritteThe General Introduction of Einstein meets Magritte Diederik Aerts, Center Leo Apostel, Brussels Free University, Brussels, Belgium. The series of books `Einstein meets Magritte' presented here

Aerts, Diederik

177

Albert Einstein, 1905: Ein 3-Gange Menu  

E-print Network

. Albert Einstein, 1905: Ein 3-G¨ange Men¨u In Zusammenarbeit mit dem Deutschen Museum Bonn 6. M: Michael Kortmann, Markus Bernhardt #12;. Albert Einstein, 1905: Ein 3-G¨ange Physik draan #12;Speiseplan Einstein 1905: Biografisches ***** Brownsche Molekularbewegung

Dutz, Hartmut

178

Einstein Room Reservations Rules and Regulations  

E-print Network

in accordance to Albert Einstein College of Medicine's Alcohol Policy. Before your request is confirmed you mustEinstein Room Reservations Rules and Regulations Before Reservation: Requests are not confirmed Activities, Joan Junger, (718) 430-2105 or student.activities@einstein.yu.edu. A meeting or conversation

Yates, Andrew

179

LOWDIMENSIONAL HOMOGENEOUS EINSTEIN MANIFOLDS CHRISTOPH B  

E-print Network

LOW­DIMENSIONAL HOMOGENEOUS EINSTEIN MANIFOLDS CHRISTOPH B Ë? OHM AND MEGAN M. KERR A closedGa] and homogeneous Einstein metrics [He], [BWZ] (cf. [Bes], [LeWa] for many more details and examples). We investigate the Einstein equation for G­invariant metrics on compact homogeneous spaces. Due to this symmetry

Kerr, Megan M.

180

Wind Power Forecasting Error Distributions over Multiple Timescales: Preprint  

SciTech Connect

In this paper, we examine the shape of the persistence model error distribution for ten different wind plants in the ERCOT system over multiple timescales. Comparisons are made between the experimental distribution shape and that of the normal distribution.

Hodge, B. M.; Milligan, M.

2011-03-01

181

Page 1 of 1 Recruitment Timescales for recruiting a member  

E-print Network

Human Resources Page 1 of 1 Recruitment ­ Timescales for recruiting a member of staff When or Human-Resources@bradford.ac.uk #12; recruiting to a position the Manager would be advised to plan carefully prior to the commencement

Zharkova, Valentina V.

182

CHEMICAL TIMESCALES IN THE ATMOSPHERES OF HIGHLY ECCENTRIC EXOPLANETS  

SciTech Connect

Close-in exoplanets with highly eccentric orbits are subject to large variations in incoming stellar flux between periapse and apoapse. These variations may lead to large swings in atmospheric temperature, which in turn may cause changes in the chemistry of the atmosphere from higher CO abundances at periapse to higher CH{sub 4} abundances at apoapse. Here, we examine chemical timescales for CO{r_reversible}CH{sub 4} interconversion compared to orbital timescales and vertical mixing timescales for the highly eccentric exoplanets HAT-P-2b and CoRoT-10b. As exoplanet atmospheres cool, the chemical timescales for CO{r_reversible}CH{sub 4} tend to exceed orbital and/or vertical mixing timescales, leading to quenching. The relative roles of orbit-induced thermal quenching and vertical quenching depend upon mixing timescales relative to orbital timescales. For both HAT-P-2b and CoRoT-10b, vertical quenching will determine disequilibrium CO{r_reversible}CH{sub 4} chemistry at faster vertical mixing rates (K{sub zz} > 10{sup 7} cm{sup 2} s{sup -1}), whereas orbit-induced thermal quenching may play a significant role at slower mixing rates (K{sub zz} < 10{sup 7} cm{sup 2} s{sup -1}). The general abundance and chemical timescale results-calculated as a function of pressure, temperature, and metallicity-can be applied for different atmospheric profiles in order to estimate the quench level and disequilibrium abundances of CO and CH{sub 4} on hydrogen-dominated exoplanets. Observations of CO and CH{sub 4} on highly eccentric exoplanets may yield important clues to the chemical and dynamical properties of their atmospheres.

Visscher, Channon [Department of Space Studies, Southwest Research Institute, Boulder, CO 80302 (United States)

2012-09-20

183

Characteristic Ultraviolet/Optical Timescales in Active Galactic Nuclei  

NASA Technical Reports Server (NTRS)

The UV/optical light curves of active galactic nuclei (AGNs) may be roughly characterized by a periodic fractional flux variations of approx. 10% on timescales of 1 month. The physical mechanism(s) responsible remain ill defined. We present a structure function analysis, i.e., measure the power distribution over a range of timescales tau, of 13 AGNs to constrain the origin of UV/optical emission. On timescales tau approx. 5- 60 days, the mean UV and optical power density spectra (PDS) are equivalent. This may suggest that the underlying energy generating mechanism is identical. The combined W/optical PDS is P(f) proportional to f(sup -alpha)- with alpha = 2.13(sup +0.22, sub -0.06). For sources with measured X-ray PDS indices, we find they are indistinguishable from their UV/optical counterparts. This supports scenarios whereby X-rays are generated via Compton upscattering of UV photons, to later radiatively drive optical variations. At the same time, we present evidence for characteristic variability timescales tau(sub char) of approx. 5-100 days in 10 sources. These variability timescales combined with reverberation based masses M suggest a M - tau(sub char) relationship; higher mass systems have larger characteristic timescales. The UV tau(sub char) may possibly reflect dynamical or accretion disk thermal timescales. We find suggestive evidence for a dichotomy, at tau approx. 30 days and M approx. l0(exp 7) solar mass, between short- and long-time scale optical variations. These optical variations may be attributable to dynamical and accretion disk thermal or starburst activity timescales, respectively.

Collier, Stefan; Peterson, Bradley M.

2001-01-01

184

Quantification of Biochar's 'Stable' Carbon on Centennial Timescales  

NASA Astrophysics Data System (ADS)

A basic requirement for any biochar offset methodology is for the carbon in biochar to be stable and remain sequestered on centennial timescales. It is well known that a variable component of most biochar is labile (degradable on annual/decadal timescales) and hence only a proportion of total carbon in biochar provides long-term carbon sequestration. This stable fraction of biochar is in the form of polycyclic aromatic carbon (PAC) but small ring size compounds (

McBeath, Anna; Bird, Michael

2014-05-01

185

Spatial Bose-Einstein Condensation.  

ERIC Educational Resources Information Center

Analyzes three examples of spatial Bose-Einstein condensations in which the particles macroscopically occupy the lowest localized state of an inhomogeneous external potential. The three cases are (1) a box with a small square potential well inside, (2) a harmonic oscillator potential, and (3) randomly sized trapping potentials caused by…

Masut, Remo; Mullin, William J.

1979-01-01

186

Schroedinger's cat in Einstein's box  

E-print Network

Using the Einstein's boxes thought experiment, as well as EPR and Heisenberg's ones, the local-realistic hidden-variable interpretation of quantum mechanics is explained. The key hidden variable is the consciousness forecasting the future. It is supposed that atoms and particles are complex products of evolution.

Raoul Nakhmanson

2005-08-19

187

A Porosity-Length Formalism for Photon-Tiring-Limited Mass Loss from Stars Above the Eddington Limit  

E-print Network

We examine radiatively driven mass loss from stars near and above the Eddington limit (Ledd). We begin by reviewing the instabilities that are expected to form extensive structure near Ledd. We investigate how this "porosity" can reduce the effective coupling between the matter and radiation. Introducing a new "porosity-length'' formalism, we derive a simple scaling for the reduced effective opacity, and use this to derive an associated scaling for the porosity-moderated, continuum-driven mass loss rate from stars that formally exceed Ledd. For a simple super-Eddington model with a single porosity length that is assumed to be on the order of the gravitational scale height, the overall mass loss is similar to that derived in previous porosity work. This is much higher than is typical of line-driven winds, but is still only a few percent of the photon tiring limit--for which the luminosity becomes insufficient to carry the flow out of the gravitational potential. To obtain still stronger mass loss that approaches observationally inferred values near this limit, we introduce a power-law-porosity model in which the associated structure has a broad range of scales. We show that the mass loss rate can be enhanced by a factor that increases with the Eddington parameter Gamma, such that for moderately large Gamma (> 3-4), mass loss rates could approach the photon tiring limit. Together with the ability to drive quite fast outflow speeds, the derived mass loss could explain the large inferred mass loss and flow speeds of giant outbursts in eta Carinae and other LBV stars.

Stanley P. Owocki; Kenneth G. Gayley; Nir J. Shaviv

2004-09-23

188

Reprint of Water renewal timescales in the Scheldt Estuary  

NASA Astrophysics Data System (ADS)

Using the concepts of the Constituent-oriented Age and Residence time Theory (CART), we compute timescales related to the water renewal in the Scheldt Estuary (The Netherlands/Belgium). Three different timescales are used to better understand and characterize the dynamics of the estuary: the age of the renewing water, the residence time and the exposure time. The residence time is the time taken by a water parcel to leave the estuary for the first time while the exposure time is the total time spent by a water parcel in the estuary including re-entries. The age of a renewing water parcel is defined as the time elapsed since it entered the estuary. The renewing water was split into three types: the water originating from the sea, the water originating from the upstream fresh tidal rivers and the water originating from the different canals and docks connected to the estuary. Every timescale is computed at any time and position by means of the finite-element, unstructured-mesh model SLIM. This results in movies of the timescale fields (shown as Supplementary material), allowing a detailed analysis of their spatial and temporal variabilities. The effect of the M2 tide and the discharge regime (winter, summer or average situation) on the timescales is also investigated.Tidally-averaged timescales vary little over the width of the estuary and hence exhibit a virtually one-dimensional behaviour. However, around these average values, the timescales can vary hugely over a tidal cycle, with amplitudes that significantly depend on the space coordinates. The reason thereof has yet to be elucidated. These results underscore the need for two- or three-dimensional models with high temporal resolution for investigating the dynamics of the Scheldt Estuary.

de Brye, Benjamin; de Brauwere, Anouk; Gourgue, Olivier; Delhez, Eric J. M.; Deleersnijder, Eric

2013-12-01

189

Timescales of Soil Moisture Anomalies: Results from Two GCMs  

NASA Technical Reports Server (NTRS)

Soil moisture anomalies dissipate over timescales that may span weeks to months. Characterizing the geographical and seasonal variations in these timescales can have important practical benefit; significant soil moisture "memory" allows long-lead forecasts of soil moisture, which have been found in recent studies to be essential for useful Ion--lead forecasts of precipitation in many regions. In this talk, we will present and compare the soil moisture timescales derived in two separate general circulation model (GCM) studies. Both studies employ multiple ensembles of short-term climate simulations. Timescales at a given point are effectively estimated by determining how quickly the soil moisture distribution generated in one ensemble of simulations (characterized by a unique set of initial soil moisture conditions) approaches that produced by another ensemble (characterized by a different set of initial soil moisture conditions). The talk will include a discussion of why the timescales produced by the two GCMs differ in some regions, and it will also describe the impact of soil moisture memory on simulated precipitation.

Koster, Randal D.; Milly, P. C. D.; Schlosser, C. Adam; Suarez, Max J.

1999-01-01

190

A diversity of localized timescales in network activity  

PubMed Central

Neurons show diverse timescales, so that different parts of a network respond with disparate temporal dynamics. Such diversity is observed both when comparing timescales across brain areas and among cells within local populations; the underlying circuit mechanism remains unknown. We examine conditions under which spatially local connectivity can produce such diverse temporal behavior. In a linear network, timescales are segregated if the eigenvectors of the connectivity matrix are localized to different parts of the network. We develop a framework to predict the shapes of localized eigenvectors. Notably, local connectivity alone is insufficient for separate timescales. However, localization of timescales can be realized by heterogeneity in the connectivity profile, and we demonstrate two classes of network architecture that allow such localization. Our results suggest a framework to relate structural heterogeneity to functional diversity and, beyond neural dynamics, are generally applicable to the relationship between structure and dynamics in biological networks. DOI: http://dx.doi.org/10.7554/eLife.01239.001 PMID:24448407

Chaudhuri, Rishidev; Bernacchia, Alberto; Wang, Xiao-Jing

2014-01-01

191

Einstein's Jury -The Race to Test Relativity  

NASA Astrophysics Data System (ADS)

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.

Crelinsten, Jeffrey

2006-12-01

192

Unifying Einstein and Palatini gravities  

SciTech Connect

We consider a novel class of f(R) gravity theories where the connection is related to the conformally scaled metric g{sub {mu}{nu}=}C(R)g{sub {mu}{nu}} with a scaling that depends on the scalar curvature R only. We call them C theories and show that the Einstein and Palatini gravities can be obtained as special limits. In addition, C theories include completely new physically distinct gravity theories even when f(R)=R. With nonlinear f(R), C theories interpolate and extrapolate the Einstein and Palatini cases and may avoid some of their conceptual and observational problems. We further show that C theories have a scalar-tensor formulation, which in some special cases reduces to simple Brans-Dicke-type gravity. If matter fields couple to the connection, the conservation laws in C theories are modified. The stability of perturbations about flat space is determined by a simple condition on the Lagrangian.

Amendola, Luca; Enqvist, Kari; Koivisto, Tomi [Institut fuer Theoretische Physik, University of Heidelberg, Philosophenweg 16, 69120 Heidelberg (Germany); Physics Department, University of Helsinki, and Helsinki Institute of Physics, FIN-00014 University of Helsinki (Finland); Institute for Theoretical Physics and Spinoza Institute, Leuvenlaan 4, 3584 CE Utrecht (Netherlands)

2011-02-15

193

Albert Einstein - a Pious Atheist  

E-print Network

We consider Einstein's attitude with regard to religion both from sociological and epistemological points of view. An attempt to put it into a wider socio-historical perspective has been made, with the emphasis on his ethnic and religious background. The great scientist was neither anatheist nor a believer in the orthodox sense and the closest labels one might apply would be pantheism/cosmism (ontological view) and agnosticism (epistemological view). His ideas on the divine could be considered as a continuation of a line that can be traced back to Philo of Alexandria, who himself followed the Greek Stoics and Neoplatonists and especially Baruch Spinoza. Einstein's scientific (or rational) and religious (or intuitive) thinking was deeply rooted in the Hellenic culture.

V. Djokovic; P. Grujic

2007-06-29

194

Albert Einstein and Scientific Theology  

E-print Network

In recent centuries the world has become increasingly dominated by empirical evidence and theoretic science in developing worldviews. Advances in science have dictated Roman Catholic doctrine such as the acceptance of Darwinian evolution and Big Bang cosmology. Albert Einstein created an indelible impact on the relationship between science and religion. The question is whether or not his work was deleterious for church doctrine or whether it was compatible with, or even advanced, church dogma. It's my contention that Einstein revived the relationship between science and theology and did not create a bifurcation between the two. Despite his personal religious beliefs, his work has helped to reinforce the harmonious conjunction of science with religion, which cannot be ignored by succeeding scientists and theologians.

Andrews, Max L E

2012-01-01

195

A. Einstein - Image and Impact  

NSDL National Science Digital Library

This online exhibit on the life of Albert Einstein takes a somewhat less orthodox approach. How did an ordinary patent clerk with an undistinguished college record evolve into one of the most profound thinkers of all time, whose contributions to theoretical physics changed the world? Was it the structure of his brain (the exhibit delves into images of Einstein's brain taken after his death). Was it the support of key friends and family members at an early age? Was it his associations with noted physicists such as Max Planck? Einsteinâs major achievements, his public and personal life, and his philosophy are all explored in this resource produced by the American Institute of Physics. Archived speech clips, photos, quotations, and essays serve to bring the exhibit to life. A âSite Contentsâ section provides an overview and facilitates navigation within the exhibit.

Physics, American I.

2012-02-01

196

Entropic corrections to Einstein equations  

SciTech Connect

Considering the general quantum corrections to the area law of black hole entropy and adopting the viewpoint that gravity interprets as an entropic force, we derive the modified forms of Modified Newtonian dynamics (MOND) theory of gravitation and Einstein field equations. As two special cases we study the logarithmic and power-law corrections to entropy and find the explicit form of the obtained modified equations.

Hendi, S. H. [Physics Department, College of Sciences, Yasouj University, Yasouj 75914 (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), Maragha (Iran, Islamic Republic of); Sheykhi, A. [Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), Maragha (Iran, Islamic Republic of); Department of Physics, Shahid Bahonar University, P.O. Box 76175-132, Kerman (Iran, Islamic Republic of)

2011-04-15

197

Correlations of the IR Luminosity and Eddington Ratio with a Hard X-ray Selected Sample of AGN  

NASA Technical Reports Server (NTRS)

We use the SWIFT Burst Alert Telescope (BAT) sample of hard x-ray selected active galactic nuclei (AGN) with a median redshift of 0.03 and the 2MASS J and K band photometry to examine the correlation of hard x-ray emission to Eddington ratio as well as the relationship of the J and K band nuclear luminosity to the hard x-ray luminosity. The BAT sample is almost unbiased by the effects of obscuration and thus offers the first large unbiased sample for the examination of correlations between different wavelength bands. We find that the near-IR nuclear J and K band luminosity is related to the BAT (14 - 195 keV) luminosity over a factor of 10(exp 3) in luminosity (L(sub IR) approx.equals L(sub BAT)(sup 1.25) and thus is unlikely to be due to dust. We also find that the Eddington ratio is proportional to the x-ray luminosity. This new result should be a strong constraint on models of the formation of the broad band continuum.

Mushotzy, Richard F.; Winter, Lisa M.; McIntosh, Daniel H.; Tueller, Jack

2008-01-01

198

The Luminosity Function of Quasars (active Galactic Nuclei) in a Merging Model with the Eddington Limit Taken Into Account  

NASA Astrophysics Data System (ADS)

The influence of Eddington's limit on the active galactic nuclei (AGN) luminosity function within the framework of a phenomenological activity model (Kats and Kontorovich, 1990, 1991) based on angular momentum compensation in the process of galaxy merging is investigated. In particular, it is shown that in spite of the essential dependence of the galaxy merging probability on their masses in the most important and interesting case it behaves effectively as a constant, so that the abovementioned (Kats and Kontorovich, 1991) correspondence between the observed galaxy mass function (Binggeli et al., 1988) and quasar luminosity function power exponents (Boyle et al., 1988; Koo and Kron, 1988; Cristiani et al., 1993) for a constant merger probability takes place in reality. A break in the power-law dependence of the luminosity function due to Eddington's restriction (cf. Dibai, 1981; Padovani and Rafanelli, 1988) is obtained in certain cases. Possible correlation between masses of black holes in AGN and masses of their host galaxies is discussed. A more detailed paper containing the results presented at this conference was published in Pis'ma v Astron. Zh. (Kontorovich and Krivitsky, 1995). Here we have added also some additional notes and references.

Kontorovich, V. M.; Krivitsky, D. S.

199

BINARY ASTEROID ENCOUNTERS WITH TERRESTRIAL PLANETS: TIMESCALES AND EFFECTS  

SciTech Connect

Many asteroids that make close encounters with terrestrial planets are in a binary configuration. Here, we calculate the relevant encounter timescales and investigate the effects of encounters on a binary's mutual orbit. We use a combination of analytical and numerical approaches with a wide range of initial conditions. Our test cases include generic binaries with close, moderate, and wide separations, as well as seven well-characterized near-Earth binaries. We find that close approaches (<10 Earth radii) occur for almost all binaries on 1-10 million year timescales. At such distances, our results suggest substantial modifications to a binary's semimajor axis, eccentricity, and inclination, which we quantify. Encounters within 30 Earth radii typically occur on sub-million year timescales and significantly affect the wider binaries. Important processes in the lives of near-Earth binaries, such as tidal and radiative evolution, can be altered or stopped by planetary encounters.

Fang, Julia; Margot, Jean-Luc [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)

2012-01-15

200

Reliability of African climate prediction and attribution across timescales  

NASA Astrophysics Data System (ADS)

This study investigates the reliability of seasonal to multi-decadal climate simulations of the wet seasons of several key African regions. It is found that reliability varies across regions and seasons, and that simulations of precipitation are universally less reliable than simulations of temperature. Similar levels of reliability are found across all the timescales considered for most (but not all) region/season combinations. Reliability for temperatures increases on longer timescales, both due to the differences in the modelling systems for each timescale and, in part, due to the contribution from systematic climate warming. Though the use of reliability is well-established for forecasting, its meaning for attribution is less clear, and further work is underway to further clarify this.

Lott, Fraser C.; Gordon, Margaret; Graham, Richard J.; Scaife, Adam A.; Vellinga, Michael

2014-10-01

201

Simulated Performance of Timescale Metrics for Aperiodic Light Curves  

E-print Network

Aperiodic variability is a characteristic feature of young stars, massive stars, and active galactic nuclei. With the recent proliferation of time domain surveys, it is increasingly essential to develop methods to quantify and analyze aperiodic variability. We develop three timescale metrics that have been little used in astronomy -- {\\Delta}m-{\\Delta}t plots, peak-finding, and Gaussian process regression -- and present simulations comparing their effectiveness across a range of aperiodic light curve shapes, characteristic timescales, observing cadences, and signal to noise ratios. We find that Gaussian process regression is easily confused by noise and by irregular sampling, even when the model being fit reflects the process underlying the light curve, but that {\\Delta}m-{\\Delta}t plots and peak-finding can coarsely characterize timescales across a broad region of parameter space. We make public the software we used for our simulations, both in the spirit of open research and to allow others to carry out ana...

Findeisen, Krzysztof; Hillenbrand, Lynne

2014-01-01

202

Two-timescale analysis of accelerated planar motions  

SciTech Connect

Two-timescale analysis has long been known as a particularly useful tool for studying dynamical systems with two different length scales. The parameter space of some accelerated worldlines shows such a situation. In this paper we find different sets of solutions for the equations of motion governing these worldlines by using two-timescale expansions. The general properties of these solutions are examined. This helps to derive simple schemes that reproduce secular effects of interacting forces. Rigorous prescriptions are given for computing the leading order motion which highlight the importance of dissipative terms in the force functions. In the end, we discuss some potential ambiguities in the two-timescale approach and possible deviations these prescriptions may have, from the exact worldlines.

Ahmadi, N. [Department of Physics, University of Tehran, North Kargar Avenue, Tehran 14395-547 (Iran, Islamic Republic of)

2011-01-15

203

A Two-Timescale Discretization Scheme for Collocation  

NASA Technical Reports Server (NTRS)

The development of a two-timescale discretization scheme for collocation is presented. This scheme allows a larger discretization to be utilized for smoothly varying state variables and a second finer discretization to be utilized for state variables having higher frequency dynamics. As such. the discretization scheme can be tailored to the dynamics of the particular state variables. In so doing. the size of the overall Nonlinear Programming (NLP) problem can be reduced significantly. Two two-timescale discretization architecture schemes are described. Comparison of results between the two-timescale method and conventional collocation show very good agreement. Differences of less than 0.5 percent are observed. Consequently. a significant reduction (by two-thirds) in the number of NLP parameters and iterations required for convergence can be achieved without sacrificing solution accuracy.

Desai, Prasun; Conway, Bruce A.

2004-01-01

204

Diffusion Time-Scale of Porous Pressure-Sensitive Paint  

NASA Technical Reports Server (NTRS)

Pressure-sensitive paint (PSP) is an optical pressure sensor that utilizes the oxygen quenching of luminescence. PSP measurements in unsteady aerodynamic flows require fast time response of the paint. There are two characteristic time-scales that are related to the time response of PSP. One is the luminescent lifetime representing an intrinsic physical limit for the achievable temporal resolution of PSP. Another is the time-scale of oxygen diffusion across the PSP layer. When the time-scale of oxygen diffusion is much larger than the luminescent lifetime, the time response of PSP is controlled by oxygen diffusion. In a thin homogenous polymer layer where diffusion is Fickian, the oxygen concentration 1021 can be described by the diffusion equation in one-dimension.

Liu, Tianshu; Teduka, Norikazu; Kameda, Masaharu; Asai, Keisuke

2001-01-01

205

MhringerWeg Albert-Einstein-Allee  

E-print Network

N MähringerWeg Oberer Eselsberg Oberer Eselsberg Albert-Einstein-Allee Helmholtzstr. James-Franck-Ring Staudingerstr. Hans- Krebs- Weg Robert-Koch-Str. Albert- Einstein- Allee W ilhelm -Runge-Str. Berliner Ring Albert- Einstein- Allee Lise- Meitner -Str. Lise-Meitner-Str. 2/1 148 11 8 8 11 5 8/1 8 10 14 12 22 20 18

Pfeifer, Holger

206

Einstein's Viscous Advice Flowed Freely Nonetheless  

NASA Astrophysics Data System (ADS)

This talk will examine a 1930 letter from Einstein to a medicinal chemistry assistant in Leiden, whose full name isn't identified in the text. I have ascertained that the letter was likely addressed to a student named Jan Lens who was writing his doctoral thesis in Utrecht on the properties of lyophilic colloids. I show how the letter refers to the Einstein relation for viscosity that first appeared in erroneous form in 1906 and corrected form in 1911. In the letter, Einstein alludes to the possibility of an extension of his formula to charged particles. It offers an interesting example of Einstein's free- flowing generosity in offering advice to students.

Halpern, Paul

2007-04-01

207

Einstein's Apple and Relativity's Gravitational Field  

E-print Network

The foundations of Einstein's first (1907) principle of equivalence are explored and their consequences are stated in terms of invariance under generalized Lorentz transformations, first explored by Hessenberg.

Engelbert L. Schucking

2009-03-23

208

GENERALIZED KILLING SPINORS ON EINSTEIN MANIFOLDS ANDREI MOROIANU, UWE SEMMELMANN  

E-print Network

GENERALIZED KILLING SPINORS ON EINSTEIN MANIFOLDS ANDREI MOROIANU, UWE SEMMELMANN Abstract. We study generalized Killing spinors on compact Einstein manifolds with posi- tive scalar curvature. This problem is related to the existence compact Einstein hypersurfaces in manifolds with parallel spinors

Semmelmann, Uwe

209

ALBERT EINSTEIN COLLEGE OF MEDICINE STRATEGIC RESEARCH PLAN UPDATE 2010  

E-print Network

1 ALBERT EINSTEIN COLLEGE OF MEDICINE STRATEGIC RESEARCH PLAN UPDATE 2010 Table community of the Albert Einstein College of Medicine have undertaken a dynamic strategic planning process/Multi-Modal Image Analysis.................10 Clinical Research Enterprise/Einstein-Montefiore Interface

Bukauskas, Feliksas

210

ALBERT EINSTEIN COLLEGE OF MEDICINE GLOBAL HEALTH FELLOWSHIP APPLICATION  

E-print Network

ALBERT EINSTEIN COLLEGE OF MEDICINE GLOBAL HEALTH FELLOWSHIP APPLICATION CLASS of____________ Return completed application to Jill Raufman at global@einstein.yu.edu by April 15th. (Medical Spanish:___________________________________________________ Name/title of mentor at Einstein: _____________________________________________________ Name

Yates, Andrew

211

Simulating Conservative Tracers in Fractured Till under Realistic Timescales  

E-print Network

Simulating Conservative Tracers in Fractured Till under Realistic Timescales by M.F. Helmke1, W solute transport through fractured till. Model results were compared to breakthrough curves (BTCs,4-piperazinediethanesulfonic acid (PIPES) in a large-diameter column of fractured till. Input parameters were determined from

Simpkins, William W.

212

Stochastic Simulation of Enzyme-Catalyzed Reactions with Disparate Timescales  

E-print Network

Stochastic Simulation of Enzyme-Catalyzed Reactions with Disparate Timescales Debashis Barik-steady-state approximation'' for enzyme-catalyzed reactions provides a useful framework for efficient and accurate stochastic simulations. The method is applied to three examples: a simple enzyme-catalyzed reaction where enzyme

Paul, Mark

213

Triggering of seismicity at short timescales following Californian earthquakes  

E-print Network

Triggering of seismicity at short timescales following Californian earthquakes D. Marsan] A method for measuring seismicity rate changes caused by the occurrence of major earthquakes in the surrounding crust is proposed. It is based on a nonstationary Poisson modeling of earthquake activity

214

On the pathways and timescales of intercontinental air pollution transport  

Microsoft Academic Search

This paper presents results of a 1-year simulation of the transport of six passive tracers, released over the continents according to an emission inventory for carbon monoxide (CO). Lagrangian concepts are introduced to derive age spectra of the tracer concentrations on a global grid in order to determine the timescales and pathways of pollution export from the continents. Calculating these

Andreas Stohl; Sabine Eckhardt; Caroline Forster; Paul James; Nicole Spichtinger

2002-01-01

215

Millennial Timescale Variations of Azimuthal Flows in the Earth's Core  

Microsoft Academic Search

Changes in the length of day at decade timescales and parts of the secular variation of the magnetic field can be both consistently explained by torsional oscillations in the Earth's fluid core. This type of flow is predicted by theory and consists of azimuthal oscillations of rigid cylindrical surfaces aligned with the rotation axis. In this work, we apply the

M. Dumberry; J. Bloxham

2004-01-01

216

Global Monsoon across timescales Pinxian Wang Bin Wang Thorsten Kiefer  

E-print Network

EDITORIAL Global Monsoon across timescales Pinxian Wang · Bin Wang · Thorsten Kiefer Published online: 28 July 2012 � Springer-Verlag 2012 Scientific focus on monsoons can be traced back nearly 350 years. However, only recently have monsoons been analyzed as a global system. Traditionally

Wang, Bin

217

A genomic timescale for the origin of eukaryotes  

Microsoft Academic Search

BACKGROUND: Genomic sequence analyses have shown that horizontal gene transfer occurred during the origin of eukaryotes as a consequence of symbiosis. However, details of the timing and number of symbiotic events are unclear. A timescale for the early evolution of eukaryotes would help to better understand the relationship between these biological events and changes in Earth's environment, such as the

S Blair Hedges; Hsiong Chen; Sudhir Kumar; Daniel Y-C Wang; Amanda S Thompson; Hidemi Watanabe

2001-01-01

218

Scaling exponents estimation from time-scale energy distributions  

Microsoft Academic Search

It is shown using some examples that the problem of estimating the evolution of scaling exponents characterizing locally a self-similar process can be efficiently handled within the general framework of time-scale energy distributions related to the wavelength transform. As is implicit from the structure of the estimators considered, the proposed methodology is dependent on the degree of nonstationarity of such

P. Goncalves; P. Flandrin

1992-01-01

219

The effect of long timescale gas dynamics on femtosecond filamentation  

E-print Network

on millisecond timescales. We show that high repetition rate filamentation and supercontinuum generation can. Srinivasan-Rao, "Supercontinuum generation in gases," Phys. Rev. Lett. 57(18), 2268­2271 (1986). S. A. Trushin, K. Kosma, W. Fuss, and W. E. Schmid, "Sub-10-fs supercontinuum radiation generated

Milchberg, Howard

220

TIMESCALES ON WHICH STAR FORMATION AFFECTS THE NEUTRAL INTERSTELLAR MEDIUM  

SciTech Connect

Turbulent neutral hydrogen (H I) line widths are often thought to be driven primarily by star formation (SF), but the timescale for converting SF energy to H I kinetic energy is unclear. As a complication, studies on the connection between H I line widths and SF in external galaxies often use broadband tracers for the SF rate, which must implicitly assume that SF histories (SFHs) have been constant over the timescale of the tracer. In this paper, we compare measures of H I energy to time-resolved SFHs in a number of nearby dwarf galaxies. We find that H I energy surface density is strongly correlated only with SF that occurred 30-40 Myr ago. This timescale corresponds to the approximate lifetime of the lowest mass supernova progenitors ({approx}8 M{sub Sun }). This analysis suggests that the coupling between SF and the neutral interstellar medium is strongest on this timescale, due either to an intrinsic delay between the release of the peak energy from SF or to the coherent effects of many supernova explosions during this interval. At {Sigma}{sub SFR} > 10{sup -3} M{sub Sun} yr{sup -1} kpc{sup -2}, we find a mean coupling efficiency between SF energy and H I energy of {epsilon} = 0.11 {+-} 0.04 using the 30-40 Myr timescale. However, unphysical efficiencies are required in lower {Sigma}{sub SFR} systems, implying that SF is not the primary driver of H I kinematics at {Sigma}{sub SFR} < 10{sup -3} M{sub Sun} yr{sup -1} kpc{sup -2}.

Stilp, Adrienne M.; Dalcanton, Julianne J.; Weisz, Daniel R.; Williams, Benjamin F. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Warren, Steven R. [Department of Astronomy, University of Maryland, CSS Building, Room 1024, Stadium Drive, College Park, MD 20742-2421 (United States); Skillman, Evan [Minnesota Institute for Astrophysics, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States); Ott, Juergen [National Radio Astronomy Observatory, P.O. Box O, 1003 Lopezville Road, Socorro, NM 87801 (United States); Dolphin, Andrew E. [Raytheon Company, 1151 East Hermans Road, Tucson, AZ 85756 (United States)

2013-08-01

221

A Cosmic Vision Beyond Einstein  

E-print Network

The acceleration of the cosmic expansion is a fundamental challenge to standard models of particle physics and cosmology. The new physics of dark energy may lie in the nature of gravity, the quantum vacuum, or extra dimensions. I give a brief overview of the puzzles and possibilities of dark energy, and discuss the confrontation of a wide variety of "beyond Einstein" models with the latest data, showing what we currently know and what we must seek to learn. Next generation experiments using a variety of cosmological probes will deeply explore dark energy, dark matter, and gravitation.

Eric V. Linder

2008-10-09

222

Cosmography with the Einstein Telescope  

E-print Network

Einstein Telescope (ET) is a 3rd generation gravitational-wave (GW) detector that is currently undergoing a design study. ET can detect millions of compact binary mergers up to redshifts 2-8. A small fraction of mergers might be observed in coincidence as gamma-ray bursts, helping to measure both the luminosity distance and red-shift to the source. By fitting these measured values to a cosmological model, it should be possible to accurately infer the dark energy equation-of-state, dark matter and dark energy density parameters. ET could, therefore, herald a new era in cosmology.

B. S. Sathyaprakash; Bernard Schutz; Chris Van Den Broeck

2009-06-23

223

Scientific Potential of Einstein Telescope  

E-print Network

Einstein gravitational-wave Telescope (ET) is a design study funded by the European Commission to explore the technological challenges of and scientific benefits from building a third generation gravitational wave detector. The three-year study, which concluded earlier this year, has formulated the conceptual design of an observatory that can support the implementation of new technology for the next two to three decades. The goal of this talk is to introduce the audience to the overall aims and objectives of the project and to enumerate ET's potential to influence our understanding of fundamental physics, astrophysics and cosmology.

B. Sathyaprakash; M. Abernathy; F. Acernese; P. Amaro-Seoane; N. Andersson; K. Arun; F. Barone; B. Barr; M. Barsuglia; M. Beker; N. Beveridge; S. Birindelli; S. Bose; L. Bosi; S. Braccini; C. Bradaschia; T. Bulik; E. Calloni; G. Cella; E. Chassande-Mottin; S. Chelkowski; A. Chincarini; J. Clark; E. Coccia; C. Colacino; J. Colas; A. Cumming; L. Cunningham; E. Cuoco; S. Danilishin; K. Danzmann; R. De. Salvo; T. Dent; R. De. Rosa; L. Di. Fiore; A. Di. Virgilio; M. Doets; V. Fafone; P. Falferi; R. Flaminio; J. Franc; F. Frasconi; A. Freise; D. Friedrich; P. Fulda; J. Gair; G. Gemme; E. Genin; A. Gennai; A. Giazotto; K. Glampedakis; C. Gräf; M. Granata; H. Grote; G. Guidi; A. Gurkovsky; G. Hammond; M. Hannam; J. Harms; D. Heinert; M. Hendry; I. Heng; E. Hennes; S. Hild; J. Hough; S. Husa; S. Huttner; G. Jones; F. Khalili; K. Kokeyama; K. Kokkotas; B. Krishnan; T. G. F. Li; M. Lorenzini; H. Lück; E. Majorana; I. Mandel; V. Mandic; M. Mantovani; I. Martin; C. Michel; Y. Minenkov; N. Morgado; S. Mosca; B. Mours; H. Müller-Ebhardt; P. Murray; R. Nawrodt; J. Nelson; R. Oshaughnessy; C. D. Ott; C. Palomba; A. Paoli; G. Parguez; A. Pasqualetti; R. Passaquieti; D. Passuello; L. Pinard; W. Plastino; R. Poggiani; P. Popolizio; M. Prato; M. Punturo; P. Puppo; D. Rabeling; I. Racz; P. Rapagnani; J. Read; T. Regimbau; H. Rehbein; S. Reid; L. Rezzolla; F. Ricci; F. Richard; A. Rocchi; S. Rowan; A. Rüdiger; L. Santamaria; B. Sassolas; R. Schnabel; C. Schwarz; P. Seidel; A. Sintes; K. Somiya; F. Speirits; K. Strain; S. Strigin; P. Sutton; S. Tarabrin; A. Thüring; J. van den Brand; M van Veggel; C. Van Den Broeck; A. Vecchio; J. Veitch; F. Vetrano; A. Vicere; S. Vyatchanin; B. Willke; G. Woan; K. Yamamoto

2011-08-05

224

Albert Einstein:. Opportunity and Perception  

NASA Astrophysics Data System (ADS)

The year 1905 has been called Albert Einstein's "Annus Mirabilis." It was during that year that he caused revolutionary changes in man's primordial concepts about the physical world: space, time, energy, light and matter. How could a 26-year-old clerk, previously unknown, cause such profound conceptual changes, and thereby open the door to the era of modern scientific technological world? No one, of course, can answer that question. But one can, perhaps, analyze some factors that were essential to his stepping into such a historic role...

Yang, Chen Ning

2013-05-01

225

Einstein's Theory of Special Relativity  

NSDL National Science Digital Library

This concise tutorial from the Physics Classroom explores a phenomenon thatis integral to Einstein's Theory of Special Relativity. This phenomenonis known as "Relativistic Length Contraction" and occurs when "the length of objects moving at relativistic speeds undergo a contraction along the dimension of motion." This may seem complicated, but the animations included in this tutorial will help you understand this intriguing concept in no time. This a great visual resource to include in class, and is helpful for anyone seeking to understand the concept of relativistic length contraction.

2007-11-14

226

The Albert Einstein College of Medicine of Yeshiva University  

E-print Network

The Albert Einstein College of Medicine of Yeshiva University EMERGENCY PROCEDURES MANUAL Prepared Resources Security Revised ­ May, 2013 #12;ALBERT EINSTEIN COLLEGE of MEDICINE of YESHIVA UNIVERSITY

Emmons, Scott

227

The Albert Einstein College of Medicine of Yeshiva University  

E-print Network

The Albert Einstein College of Medicine of Yeshiva University EMERGENCY PROCEDURES MANUAL Prepared Supporting Services Revised ­ January, 2012 #12;ALBERT EINSTEIN COLLEGE of MEDICINE of YESHIVA UNIVERSITY

Yates, Andrew

228

Einstein as a Missionary of Science  

ERIC Educational Resources Information Center

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…

Renn, Jürgen

2013-01-01

229

Einstein Manifolds as Yang-Mills Instantons  

NASA Astrophysics Data System (ADS)

It is well known that Einstein gravity can be formulated as a gauge theory of Lorentz group where spin connections play a role of gauge fields and Riemann curvature tensors correspond to their field strengths. One can then pose an interesting question: What is the Einstein equation from the gauge theory point of view? Or equivalently, what is the gauge theory object corresponding to Einstein manifolds? We show that the Einstein equations in four dimensions are precisely self-duality equations in Yang-Mills gauge theory and so Einstein manifolds correspond to Yang-Mills instantons in SO(4) = SU(2)L × SU(2)R gauge theory. Specifically, we prove that any Einstein manifold with or without a cosmological constant always arises as the sum of SU(2)L instantons and SU(2)R anti-instantons. This result explains why an Einstein manifold must be stable because two kinds of instantons belong to different gauge groups, instantons in SU(2)L and anti-instantons in SU(2)R, and so they cannot decay into a vacuum. We further illuminate the stability of Einstein manifolds by showing that they carry nontrivial topological invariants.

Oh, John J.; Yang, Hyun Seok

2013-07-01

230

What Einstein Can Teach Us about Education  

ERIC Educational Resources Information Center

People are more likely to associate Einstein with complex scientific theories and mathematical calculations than with education theory. In fact, Einstein's own experiences of schooling and his reflections on the meaning of life and the significance of education are profound and oddly relevant to the situation that pertains in England today. It is…

Hayes, Denis

2007-01-01

231

Quantum Einstein's Equations and Constraints Algebra  

E-print Network

In this paper we shall address this problem: Is quantum gravity constraints algebra closed and what are the quantum Einstein equations. We shall investigate this problem in the de-Broglie--Bohm quantum theory framework. It is shown that the constraint algebra is weakly closed and the quantum Einstein's equations are derived.

Fatimah Shojai; Ali Shojai

2001-09-16

232

Books on Einstein--Collectors' Delight  

ERIC Educational Resources Information Center

A survey of thirteen books on Einstein is presented. Its gives an idea on how much is written about the man and how frequent are the publications. The year 2005 saw the most publications. It is the centenary for the Miraculous Year. Interestingly some books can just sustain their readers' interest with just words. Einstein comes alive with the…

Khoon, Koh Aik; Jalal, Azman; Abd-Shukor, R.; Yatim, Baharudin; Talib, Ibrahim Abu; Daud, Abdul Razak; Samat, Supian

2009-01-01

233

Einstein's Jury: The Race to Test Relativity  

Microsoft Academic Search

'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

Jürgen Ehlers

2007-01-01

234

A Possible Reinterpretation of Einstein's Equations  

NASA Astrophysics Data System (ADS)

In this paper, we first review Huei’s formulation in which it is shown that the linearized Einstein equations can be written in the same form as the Maxwell equations. We eliminate some imperfections like the scalar potential which is ill linked to the electric-type field, the Lorentz-type force which is obtained with a time independence restriction and the undesired factor 4 which appears in the magnetic-type part. Second, from these results and in the light of a recent work by C.C. Barros, we propose an extension of the equivalence principle and we suggest a new interpretation for Einstein’s equations by showing that the electromagnetic Maxwell equations can be derived from a new version of Einstein’s ones.

Bouda, A.; Belabbas, A.

2010-10-01

235

OWL representation of the geologic timescale implementing stratigraphic best practice  

NASA Astrophysics Data System (ADS)

The geologic timescale is a cornerstone of the earth sciences. Versions are available from many sources, with the following being of particular interest: (i) The official International Stratigraphic Chart (ISC) is maintained by the International Commission for Stratigraphy (ICS), following principles developed over the last 40 years. ICS provides the data underlying the chart as part of a specialized software package, and the chart itself as a PDF using the standard colours; (ii) ITC Enschede has developed a representation of the timescale as a thesaurus in SKOS, used in a Web Map Service delivery system; (iii) JPL's SWEET ontology includes a geologic timescale. This takes full advantage of the capabilities of OWL. However, each of these has limitations - The ISC falls down because of incompatibility with web technologies; - While SKOS supports multilingual labelling, SKOS does not adequately support timescale semantics, in particular since it does not include ordering relationships; - The SWEET version (as of version 2) is not fully aligned to the model used by ICS, in particular not recognizing the role of the Global Boundary Stratotype Sections and Point (GSSP). Furthermore, it is distributed as static documents, rather than through a dynamic API using SPARQL. The representation presented in this paper overcomes all of these limitations as follows: - the timescale model is formulated as an OWL ontology - the ontology is directly derived from the UML representation of the ICS best practice proposed by Cox & Richard [2005], and subsequently included as the Geologic Timescale package in GeoSciML (http://www.geosciml.org); this includes links to GSSPs as per the ICS process - key properties in the ontology are also asserted to be subProperties of SKOS properties (topConcept and broader/narrower relations) in order to support SKOS-based queries; SKOS labelling is used to support multi-lingual naming and synonyms - the International Stratigraphic Chart is implemented as a set of instances of classes from the ontology, and published through a SPARQL end-point - the elements of the Stratigraphic chart are linked to the corresponding elements in SWEET (Raskin et al., 2011) and DBpedia to support traceability between different commonly accessed representations. The ontology builds on standard geospatial information models, including the Observations and Measurements model (ISO 19156), and GeoSciML. This allows the ages given in the chart to be linked to the evidence basis found in the associated GeoSciML features.

Cox, S. J.

2011-12-01

236

A two-timescale approach to nonlinear Model Predictive Control  

SciTech Connect

Model Predictive Control (MPC) schemes generate controls by using a model to predict the plant`s response to various control strategies. A problem arises when the underlying model is obtained by fitting a general nonlinear function, such as a neural network, to data: an exorbitant amount of data may be required to obtain accurate enough predictions. We describe a means of avoiding this problem that involves a simplified plant model which bases its predictions on averages of past control inputs. This model operates on a timescale slower than- the rate at which the controls are updated and the plant outputs are sampled. Not only does this technique give better closed-loop performance from the same amount of open-loop data, but it requires far less on-line computation as well. We illustrate the usefulness of this two-timescale approach by applying it to a simulated exothermic continuously stirred tank reactor with jacket dynamics.

Buescher, K.L.; Baum, C.C.

1994-10-01

237

Timescales Trips to PG Quasars: The Mkn 478 Case  

NASA Astrophysics Data System (ADS)

The X-ray bright PG quasar PG 1440+356 (Mkn 478) was observed four times across 13 months with the XMM-Newton observatory. Flux variations with a dynamical range of a factor about 6 were observed in both the soft (E < 1 keV) and the hard (E > 3 keV) X-ray band. However, large spectral variations are observed in the latter band only. We suggest that the X-ray emission in this object is due to Comptonization of kT ? 60 eV disk photons by a 20--50 keV plasma with a complex density structure. Analysis of the harmonic content of Mkn 478 light curves unveils a characteristic timescale ˜1 day, common to both energy bands. A longer (˜months) timescale is detected in the soft X-ray band only.

Guainazzi, M.; Loiseau, N.; Matt, G.; Orr, A.

238

The Behavior of the Lithosphere on Seismic to Geologic Timescales  

NASA Astrophysics Data System (ADS)

The strength of the lithosphere and how it responds to loading and unloading are fundamental problems with wide implications. Flexure studies suggest that the elastic thickness, a proxy for the strength of the lithosphere, increases with plate age but decreases with load age. The elastic thickness is significantly less than the seismic thickness of the lithosphere, as indicated by the depth to the low-velocity zone, suggesting that the lithosphere is a strong structure at short seismic timescales and a weak one at long timescales. The mechanism controlling this weakening is not known, but it probably involves some form of load-induced stress relaxation. Despite weakening, the lithosphere is capable of retaining its strength and supporting loads such as volcanoes and sediments for long periods of geological time. Lithosphere relaxation should be included in geodynamical models, especially as it has impacts on stratigraphy, sea-level change, and dynamic topography.

Watts, A. B.; Zhong, S. J.; Hunter, J.

2013-05-01

239

The Timescale and Mode of Star Formation in Clusters  

E-print Network

I discuss two questions about the origin of star clusters: How long does the process take? What is the mode of individual star formation? I argue that observations of Galactic star-forming regions, particularly the Orion Nebula Cluster (ONC), indicate that cluster formation often takes several Myr, which is many local dynamical timescales. Individual stars and binaries, including massive stars, appear to form from the collapse of gas cores.

Jonathan C. Tan

2004-07-05

240

TimeScale Feature Extractions for Emotional Speech Characterization  

Microsoft Academic Search

Abstract,Emotional,speech,characterization,is,an important issue for the understanding,of interaction. This article discusses the time-scale analysis problem in feature extraction for emotional speech processing. We describe a computational,framework,for combining,segmental,and supra-segmental features for emotional,speech detection. The statistical fusion is based on the estimation of local a posteriori class probabilities and the overall decision employs,weighting factors directly related to the duration of the individual speech

Mohamed Chetouani; Ammar Mahdhaoui; Fabien Ringeval

2009-01-01

241

Timescales of fluvial activity and intermittency in Milna Crater, Mars  

NASA Astrophysics Data System (ADS)

Milna Crater, Mars (23.4S, 12.3W) exhibits signs of fluvial modification early in Mars history, including a large multi-lobed fan deposit cut by several sinuous valleys. We describe the past hydrologic conditions in Milna and the surrounding area, including a potential lake with a volume of 50 km3. We also introduce new methods (i) to calculate the timescale of sediment deposition by considering fluvial sediment input into the entire crater while accounting for non-fluvial input, and (ii) to place improved constraints on the channel dimensions through which sediment was delivered to Milna by comparing to the dimensions of inner channels found in valleys in the region surrounding Milna. By calculating the flux of fluid and sediment into the crater, we find that the crater cavity was flooded for at least months and that the time of active fluvial sediment transport without hiatus is on the order of decades to centuries, with a preferred timescale of centuries. We also calculate the total amount of water required to transport the volume of sediment we measure in Milna and conclude that impacts alone are likely insufficient to deliver enough water to Milna to allow the sedimentary fill we see. Combining the timescales of fluvial activity in the adjacent Paraná Valles with estimates for global Noachian erosion rates, we calculate an intermittency factor for fluvial activity of ?0.01-0.1% during 105-106 yr near the Noachian-Hesperian boundary in the Paraná Valles region. These values are comparable to arid climates on Earth where the majority of fluvial sedimentary transport takes place during floods with multi-year to decadal recurrence intervals. Our calculations of intermittency help to quantitatively reconcile the divergent estimates of the short and long timescales of fluvial activity on Mars reported in the literature.

Buhler, Peter B.; Fassett, Caleb I.; Head, James W.; Lamb, Michael P.

2014-10-01

242

Geol 102 Historical Geology The Geologic Timescale 2009  

E-print Network

Geol 102 Historical Geology The Geologic Timescale 2009 EON ERA PERIOD (Special Units) EPOCH Range.5 - 55.8 Mesozoic Cretaceous 145.5 - 65.5 Jurassic 199.6 - 145.5 Triassic 251.0 - 199.6 Paleozoic Permian 299.0 - 251.0 Carboniferous Pennsylvanian Sub-period 318.1 - 299.0 Mississippian Sub-period 359

Holtz Jr., Thomas R.

243

Geol 102 Historical Geology The Geologic Timescale 2011  

E-print Network

Geol 102 Historical Geology The Geologic Timescale 2011 EON ERA PERIOD (Special Units) EPOCH Range 65.5 - 55.8 Mesozoic Cretaceous 145.5 - 65.5 Jurassic 201.5 - 145.5 Triassic 252.3 - 201.5 Paleozoic Permian 299.0 - 252.3 Carboniferous Pennsylvanian Sub-period 318.1 - 299.0 Mississippian Sub-period 359

Holtz Jr., Thomas R.

244

Geol 102 Historical Geology The Geologic Timescale 2012  

E-print Network

Geol 102 Historical Geology The Geologic Timescale 2012 EON ERA PERIOD (Special Units) EPOCH Range.332 Oligocene 33.9 - 23.03 Eocene 56.0 - 33.9 Paleocene 66.0 - 56.0 Cretaceous 145.0 - 66.0 Jurassic 201.3 - 145.0 Triassic 252.2 - 201.3 Permian 298.9 - 252.2 Pennsylvanian Sub-period 323.2 - 298.9 Mississippian Sub-period

Holtz Jr., Thomas R.

245

A pseudo-Bertrand distribution for time-scale analysis  

Microsoft Academic Search

Using the pseudo-Wigner time-frequency distribution as a guide, we derive two new time-scale representations: the pseudo-Bertrand and the smoothed pseudo-Bertrand distributions. Unlike the Bertrand distribution, these representations support efficient online operation at the same computational cost as the continuous wavelet transform. Moreover, they take advantage of the affine smoothing inherent in the sliding structure of their implementation to suppress cumbersome

P. Goncalves; R. G. Baraniuk

1996-01-01

246

Toppling the Timescale Part III: Madness in the Methods  

E-print Network

The chronology of the geologic timescale’s stratigraphic units has been defined by a variety of methods. Over the decades many have waxed and waned in popularity, but at present the most important ones are: (1) radiometric dating, (2) astronomical “tuning, ” (3) magnetostratigraphy, and (4) biostratigraphy. Each of these methods assumes deep time and uniformitarianism rather than demonstrating them. Each also exhibits other specific flaws. These are commonly masked by the “shotgun approach ” or the selective use of individual methods. But contrary to popular perception, the “shotgun approach” does not demonstrate the strength of overlapping independent, scientific methods, but instead exhibits a critical weakness—after decades of searching, no single absolute chronometer has been found. The frequent selective shuffling of methods, therefore, demonstrates the failure to attain a real chronology. Thus the absolute timescale (and its stages) rests on quicksand. It is not the concrete empirical history commonly presented; it is instead the unverified historical saga of the worldview of Naturalism, supported more by the faith of its adherents than by factual demonstration.

John K. Reed

247

STP Einstein Solid Heat Bath Program  

NSDL National Science Digital Library

The STP EinsteinSolidHeatBath program simulates the exchange of energy between an Einstein solid and a heat bath. The purpose of this simulation is to determine the properties of a Einstein solid at different temperature T and to compare our results with analytical calculations of the thermodynamic properties of the Einstein solid. The default state is an Einstein solid of N=20 particles in contact with a heat bath at temperature T = 2. Additional states and parameters can be specified using the Display|Switch GUI menu item. STP EinsteinSolidHeatBath is part of a suite of Open Source Physics programs that model aspects of Statistical and Thermal Physics (STP). The program is distributed as a ready-to-run (compiled) Java archive. Double-clicking the stp_EinsteinSolidHeatBath.jar file will run the program if Java is installed on your computer. Additional programs can be found by searching ComPADRE for Open Source Physics, STP, or Statistical and Thermal Physics.

Gould, Harvey; Tobochnik, Jan; Christian, Wolfgang; Cox, Anne

2008-05-28

248

Feedback strengths estimated from observations at seasonal and decadal timescales  

NASA Astrophysics Data System (ADS)

Quantifying the expected surface temperature response to radiative forcing, or climate sensitivity, from the observational record is complicated by the uncertain amount of ocean heat uptake, which delays equilibration. From a global mean perspective, rates of ocean heat uptake and surface warming multiplied by feedback strength are largely interchangeable when the system is transiently adjusting to increased radiative forcing. In our previous work, the spatial pattern of oceanic influence upon atmospheric temperature variability was assessed through a Lagrangian back trajectory analysis and applied to explain the phase and amplitude of the seasonal cycle, as well as patterns of temperature change. Here, we combine these previous results with an assumed uniform feedback strength in a simple, analytical model for local temperature variability for the observed seasonal cycle and recent inter-decadal temperature changes. The model predicts a pattern of temperature change between 1950 and 2012 that is significantly correlated with the observed change (r = 0.68, p-value < 0.01). The predictions capture more than simple land-sea contrast, also explaining a significant portion of the inter-decadal transient changes over only ocean (r = 0.36, p-value < 0.01) and only land (r = 0.44, p-value = 0.04). Significances are estimated using surrogate data generated via two-dimensional phase randomization. Importantly, the spatial component of the model permits for distinguishing between the influence of ocean heat uptake and the strength of the net feedback for both the seasonal cycle and inter-decadal temperature change. As expected, effective ocean heat capacity, which is indicative of the depth of the ocean interacting with the surface on each timescale in our simple formulation, is found to be smaller for the seasonal cycle than for longer timescales. More interestingly, the net feedback is found to be significantly more negative on seasonal timescales, suggesting stronger positive feedbacks at inter-decadal timescales. To better identify the physical mechanisms responsible for the timescale dependence in feedback strength, we apply the radiative kernel method to NCAR CCSM4 and explore the differences in atmospheric feedbacks for the seasonal cycle and inter-decadal forced changes.

McKinnon, K. A.; Huybers, P. J.; Bitz, C. M.

2013-12-01

249

Einstein's Theory Fights off Challengers  

NASA Astrophysics Data System (ADS)

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 c

2010-04-01

250

Bose-Einstein Condensate strings  

E-print Network

We consider the possible existence of gravitationally bound general relativistic strings consisting of Bose-Einstein Condensate (BEC) matter which is described, in the Newtonian limit, by the zero temperature time-dependent nonlinear Schr{\\"}odinger equation (the Gross-Pitaevskii equation), with repulsive inter-particle interactions. In the Madelung representation of the wave function, the quantum dynamics of the condensate can be formulated in terms of the classical continuity equation and the hydrodynamic Euler equations. In the case of a condensate with quartic nonlinearity, the condensates can be described as a gas with two pressure terms, the interaction pressure, which is proportional to the square of the matter density, and the quantum pressure, which is without any classical analogue though, when the number of particles in the system is high enough, the latter may be neglected. By assuming cylindrical symmetry, we analyze the physical properties of the BEC strings in both the interaction pressure and ...

Harko, Tiberiu

2014-01-01

251

Einstein Light: Galilean Relativity and Newtonian Mechanics  

NSDL National Science Digital Library

This animated tutorial, part of the Einstein Light website, presents the concept of relativity from a situation inspired by Galileo (an inertial reference frame). It shows the motion of a ball being dropped from two reference frames: on a moving train and on a stationary platform. How does the motion appear different to the observer on the platform and the observer on the train? The Einstein Light project is a qualitative introduction to relativity, developed for novice learners and built around the framework of Flash media files with narration, video, and animation. It explores concepts ranging from Galilean relativity through Einstein and quantum mechanics.

Wolfe, Joe; Hatsidimitris, George

2007-12-20

252

Stability of the Einstein static universe in Einstein-Cartan theory  

NASA Astrophysics Data System (ADS)

The existence and stability of the Einstein static solution have been built in the Einstein-Cartan gravity. We show that this solution in the presence of perfect fluid with spin density satisfying the Weyssenhoff restriction is cyclically stable around a center equilibrium point. Thus, study of this solution is interesting because it supports non-singular emergent cosmological models in which the early universe oscillates indeterminately about an initial Einstein static solution and is thus past eternal.

Atazadeh, K.

2014-06-01

253

Stability of the Einstein static universe in Einstein-Cartan theory  

E-print Network

The existence and stability of the Einstein static solution have been built in the Einstein-Cartan gravity. We show that this solution in the presence of perfect fluid with spin density satisfying the Weyssenhoff restriction is cyclically stable around a center equilibrium point. Thus, study of this solution is interesting because it supports non-singular emergent cosmological models in which the early universe oscillates indeterminately about an initial Einstein static solution and is thus past eternal.

Atazadeh, K

2014-01-01

254

Stability of the Einstein static universe in Einstein-Cartan theory  

E-print Network

The existence and stability of the Einstein static solution have been built in the Einstein-Cartan gravity. We show that this solution in the presence of perfect fluid with spin density satisfying the Weyssenhoff restriction is cyclically stable around a center equilibrium point. Thus, study of this solution is interesting because it supports non-singular emergent cosmological models in which the early universe oscillates indeterminately about an initial Einstein static solution and is thus past eternal.

K. Atazadeh

2014-01-29

255

Albert Einstein and Archenhold Observatory 1905 - 2005 (German Title: Albert Einstein und die Archenhold-Sternwarte 1905 -- 2005)  

Microsoft Academic Search

After Einstein came to Berlin, he gave his first popular lecture in the Archenhold Observatory, in 1915, on the special and the general theories of relativity. From then on, friendly relations grew between Archenhold and Einstein, which led to a permanent connection between the Observatory and Einstein's achievement. This contribution presents the background of the connection between Archenhold and Einstein,

Dieter B. Herrmann

2005-01-01

256

Einstein and General Relativity: Historical Perspectives.  

ERIC Educational Resources Information Center

This paper presented in the 1978 Oppenheimer Memorial Lecture at Los Alamos Scientific Laboratories on August 17, 1978, discusses Einstein's contributions to physics, in particular, his discovery of the general theory of relativity. (HM)

Chandrasekhar, S.

1979-01-01

257

Einstein's Energy-Free Gravitational Field  

E-print Network

We show that Einstein's gravitational field has zero energy, momentum, and stress. This conclusion follows directly from the gravitational field equations, in conjunction with the differential law of energy-momentum conservation $ T^{\\mu\

Kenneth Dalton

1995-12-04

258

Quantum reflection of Bose-Einstein Condensates  

E-print Network

Recent developments in atom optics have brought Bose-Einstein condensates within 1 pm of solid surfaces where the atom-surface interactions can no longer be ignored. At long- range, the atom-surface interaction is described ...

Pasquini, Thomas A., Jr

2007-01-01

259

Einstein e os Bilogos Gisele A. Oda  

E-print Network

encontro emocionante em seu livro autobiográfico "Life Cycles: Reflection of an Evolutionary Biologist". No mesmo livro, relata também o encontro entre Einstein e Karl Von Frisch(**), da forma como ele o

Ribas, Roberto Vicençotto

260

Einstein/Roosevelt Letters: A Unit.  

ERIC Educational Resources Information Center

The letters in this unit of study intended for secondary students are facsimile reproductions of the correspondence between Albert Einstein and President Roosevelt on the possibility of constructing an atomic bomb. Classroom activities are also suggested. (RM)

Bodle, Walter S.

1985-01-01

261

STP Temperature Measurement Einstein Solid Program  

NSDL National Science Digital Library

The STP DemonEinsteinSolid program displays a histogram of the energy of a demon that exchanges energy with an ideal gas of particles. The purpose of this simulation is to understand how the demon acts as an ideal thermometer. The default system is an Einstein solid of N=40 particles. Additional states and parameters can be specified using the Display|Switch GUI menu item. STP DemonEinsteinSolid is part of a suite of Open Source Physics programs that model aspects of Statistical and Thermal Physics (STP). The program is distributed as a ready-to-run (compiled) Java archive. Double-clicking the stp_DemonEinsteinSolid.jar file will run the program if Java is installed on your computer. Additional programs can be found by searching ComPADRE for Open Source Physics, STP, or Statistical and Thermal Physics.

Gould, Harvey; Tobochnik, Jan; Christian, Wolfgang; Cox, Anne

2008-05-28

262

The creativity of Einstein and astronomy  

NASA Technical Reports Server (NTRS)

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.

Zeldovich, Y. B.

1980-01-01

263

Bose-Einstein Condensation in Microgravity  

NASA Astrophysics Data System (ADS)

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.

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.

2010-06-01

264

How History Helped Einstein in Special Relativity  

NASA Astrophysics Data System (ADS)

I will discuss how the German intellectual movement known as ``critical history'' motivated several physicists in the late 1900s to radically analyze the fundamental principles of mechanics, leading eventually to Einstein's special theory of relativity. Eugen Karl Dühring, Johann Bernhard Stallo, Ludwig Lange, and Ernst Mach wrote critical histories of mechanics, some of which emphasized notions of relativity and observation, in opposition to old metaphysical concepts that seemed to infect the foundations of physics. This strand of critical history included the ``genetic method'' of analyzing how concepts develop over time, in our minds, by way of ordinary experiences, which by 1904 was young Albert Einstein's favorite approach for examining fundamental notions. Thus I will discuss how history contributed in Einstein's path to relativity, as well as comment more generally on Einstein's views on history.

Martinez, Alberto

2013-04-01

265

The happiest thought of Einstein's life.  

NASA Astrophysics Data System (ADS)

It is a commonly told story that Einstein formulated his famous principle of equivalence when thinking about what happens in a freely falling elevator, and that it was an original idea of his genius distinguished by the rare capability to see deep problems in the most ordinary things. In the reading of Einstein's and Ernst Mach's works the author has discovered that it was not a physicist in an elevator which led to the principle of equivalence but rather somebody falling from a roof; moreover, the idea behind the principle was not invented by Einstein himself but rather read by him from the book by Mach entitled The Science of Mechanics. The influence this book had on young Einstein is very well known.

Heller, M.

266

Human dynamics: Darwin and Einstein correspondence patterns  

Microsoft Academic Search

In an era when letters were the main means of exchanging scientific ideas and results, Charles Darwin (1809-82) and Albert Einstein (1879-1955) were notably prolific correspondents. But did their patterns of communication differ from those associated with the instant-access e-mail of modern times? Here we show that, although the means have changed, the communication dynamics have not: Darwin's and Einstein's

João Gama Oliveira; Albert-László Barabási

2005-01-01

267

Einstein's Biggest Blunder: A Cosmic Mystery Story  

SciTech Connect

The standard model of cosmology built up over 20 years is no longer accepted as accurate. New data suggest that most of the energy density of the universe may be contained in empty space. Remarkably, this is exactly what would be expected if Einstein's cosmological constant really exists. If it does, its origin is the biggest mystery in physics and presents huge challenges for the fundamental theories of elementary particles and fields. Krauss explains Einstein's concept and describes its possible implications.

Lawrence Krauss

2007-05-30

268

Einstein's Apple: His First Principle of Equivalence  

E-print Network

After a historical discussion of Einstein's 1907 principle of equivalence, a homogeneous gravitational field in Minkowski spacetime is constructed. It is pointed out that the reference frames in gravitational theory can be understood as spaces with a flat connection and torsion defined through teleparallelism. This kind of torsion was introduced by Einstein in 1928. The concept of torsion is discussed through simple examples and some historical observations.

Engelbert L. Schucking; Eugene J. Surowitz

2007-03-29

269

Einstein's Biggest Blunder: A Cosmic Mystery Story  

ScienceCinema

The standard model of cosmology built up over 20 years is no longer accepted as accurate. New data suggest that most of the energy density of the universe may be contained in empty space. Remarkably, this is exactly what would be expected if Einstein's cosmological constant really exists. If it does, its origin is the biggest mystery in physics and presents huge challenges for the fundamental theories of elementary particles and fields. Krauss explains Einstein's concept and describes its possible implications.

Lawrence Krauss

2010-09-01

270

Compaction and contraction: Densification timescales of porous magmas  

NASA Astrophysics Data System (ADS)

Cyclic explosive volcanic eruptions are often thought to be characterised by the formation and subsequent destruction of a dense, less-permeable plug. We investigated the timescales and deformation mechanisms that could lead to the formation of a denser plug or volcanic dome. We experimentally simulated conditions conducive to (1) high porosity magma compaction and (2) sintering of heterogeneous distributions of pyroclasts. Both of these processes likely play a role in conduit densification. High porosity magmas are texturally unstable when the included gas phase becomes connected and thereby depressurises at shallow levels. Within a scenario of syn-eruptive, decompression-driven vesiculation and crack network development during highly explosive events such as cyclic Vulcanian eruptions, unerupted magma that has developed high porosity in the vent will densify if the volcanic conduit temperatures remain high enough to suppress a significant melt viscosity increase. Further, fragmented material falling back into a hot volcanic conduit or that is forced into cracks in dense magma (tuffisites) will sinter and densify over similar timescales. We explore this densification timescale experimentally by returning erupted pumice (February 2010, Soufriere Hills volcano) to magmatic temperatures and measuring the evolution of the pore network via helium pycnometry, ultrasonic wave velocities and volumetric determinations. We find that magma can recover the high densities and low porosities typical of dome-forming magma over timescales proportional to 1) the viscosity of the melt phase, 2) the melt surface tension and 3) a measure of the dominant pore geometry and distribution. On this basis, we present a unique expression for the evolution of porosity or density as a function of the structural relaxation time of the melt phase. Finally, gas permeability and Lattice Boltzmann simulations on rendered pore volumes from 3D X-Ray computed micro-tomography elucidate the changing efficiency with which pore pressure can be dissipated during ductile densification. These tools enable a discussion of likely scenarios for the explosive-effusive transition, evolving suspension rheology and the repose interval of cyclic eruptions as well as the testing of current conceptual models of dense plug formation.

Wadsworth, F. B.; Scheu, B.; Vasseur, J.; kennedy, B.; Lavallee, Y.; Jones, T.; Hess, K.; Heap, M. J.; Dingwell, D. B.

2013-12-01

271

Conical Kähler-Einstein Metrics Revisited  

NASA Astrophysics Data System (ADS)

In this paper we introduce the "interpolation-degeneration" strategy to study Kähler-Einstein metrics on a smooth Fano manifold with cone singularities along a smooth divisor that is proportional to the anti-canonical divisor. By "interpolation" we show the angles in (0, 2?] that admit a conical Kähler-Einstein metric form a connected interval, and by "degeneration" we determine the boundary of the interval in some important cases. As a first application, we show that there exists a Kähler-Einstein metric on with cone singularity along a smooth conic (degree 2) curve if and only if the angle is in (?/2, 2?]. When the angle is 2?/3 this proves the existence of a Sasaki-Einstein metric on the link of a three dimensional A 2 singularity, and thus answers a question posed by Gauntlett-Martelli-Sparks-Yau. As a second application we prove a version of Donaldson's conjecture about conical Kähler-Einstein metrics in the toric case using Song-Wang's recent existence result of toric invariant conical Kähler-Einstein metrics.

Li, Chi; Sun, Song

2014-11-01

272

The identification of an optical counterpart to the super-Eddington X-ray source, NGC 5204 X-1  

E-print Network

We report the identification of a possible optical counterpart to the super-Eddington X-ray source NGC 5204 X-1. New Chandra data shows that the X-ray source is point-like, with a luminosity of 5.2 x 10^39 erg/s (0.5 - 8 keV). It displays medium- and long-term X-ray variability in observations spanning a period of 20 years. The accurate Chandra position allows us to identify a blue optical continuum source (m_v = 19.7) at the position of NGC 5204 X-1, using newly-obtained optical data from the INTEGRAL instrument on the William Herschel Telescope. The X-ray and optical source properties are consistent with the scenario in which we are observing the beamed X-ray emission of a high-mass X-ray binary in NGC 5204, composed of an O star with either a black hole or neutron star companion.

T. P. Roberts; M. R. Goad; M. J. Ward; R. S. Warwick; P. T. O'Brien; P. Lira; A. D. P. Hands

2001-05-17

273

Radiation hydrodynamic instability in a plane-parallel, super-Eddington atmosphere: A mechanism for clump formation  

NASA Astrophysics Data System (ADS)

In order to understand the physical processes underlying clump formation in outflow from supercritical accretion flow, we perform two-dimensional radiation hydrodynamic (RHD) simulations. We focus our discussion on the nature of RHD instability in a marginally optically thick, plane-parallel, super-Eddington atmosphere. Initially we set a two-layered atmosphere with a density contrast of 100 exposed to strong, upward continuum-radiation force; the lower layer is denser than the upper one, the condition for RHD instability. We assume non-zero but negligible gravitational force, compared with the radiation force. We find that short-wavelength perturbations grow first, followed by the growth of longer-wavelength patterns, which lead to the formation of clumpy structure. The typical size of clumps (clouds) corresponds to about one optical depth. An anti-correlation between the radiation pressure and the gas pressure is confirmed: this anti-correlation provides a damping mechanism for perturbations of longer wavelength than the typical clump size. Matter and radiation energy densities are correlated. These features are exactly what we found in the radiation-magnetohydrodynamic (radiation-MHD) simulations of supercritical outflow.

Takeuchi, Shun; Ohsuga, Ken; Mineshige, Shin

2014-04-01

274

The relationship between the Eddington limit, the observed upper luminosity limit for massive stars, and the luminous blue variables  

NASA Technical Reports Server (NTRS)

The observed upper luminosity limits in the Galaxy and the LMC are compared with the Eddington limit as estimated for plane-parallel LTE model atmospheres which include the full effects of metal line opacities in the ultraviolet. It is shown that the Humphreys-Davidson (HD) limit corresponds to the locus of extremely low effective gravities. This result suggests that stars approaching the HD limit will suffer high mass-loss rates because of the reduction of the effective gravity due to radiation pressure. These high mass-loss rates ultimtely lead to the core mass fraction reaching its critical value and the reversal of the stellar evolution tracks. It is shown that radiation pressure, as an agent for producing enhanced mass loss near the HD limit, can in a natural way explain the kink in the HD limit near T(eff) roughly 10,000 K and the upper luminosity limit for yellow and red supergiants. The high mass-loss rates of the luminous blue variables, their location in the HR diagram, and their evolutionary stage are also discussed.

Lamers, Henny J. G. L. M.; Fitzpatrick, Edward L.

1988-01-01

275

Three-dimensional general relativistic radiation magnetohydrodynamical simulation of super-Eddington accretion, using a new code HARMRAD with M1 closure  

NASA Astrophysics Data System (ADS)

Black hole (BH) accretion flows and jets are dynamic hot relativistic magnetized plasma flows whose radiative opacity can significantly affect flow structure and behaviour. We describe a numerical scheme, tests, and an astrophysically relevant application using the M1 radiation closure within a new 3D general relativistic radiation magnetohydrodynamics (GRRMHD) massively parallel code called HARMRAD. Our 3D GRRMHD simulation of super-Eddington accretion (about 20 times Eddington) on to a rapidly rotating BH (dimensionless spin j = 0.9375) shows sustained non-axisymmemtric disc turbulence, a persistent electromagnetic jet driven by the Blandford-Znajek effect, a disc wind, and a polar radiation jet. The total accretion efficiency is of the order of 20 per cent, the large-scale electromagnetic jet efficiency is of the order of 10 per cent, the disc wind efficiency is less than 1 per cent, and the total radiative efficiency remains low at only of the order of 1 per cent (of order the Eddington luminosity). However, the radiation jet and the electromagnetic jet both emerge from a geometrically beamed polar region, with super-Eddington isotropic equivalent luminosities. Such simulations with HARMRAD can enlighten the role of BH spin versus discs in launching jets, help determine the origin of spectral and temporal states in X-ray binaries, help to understand how tidal disruption events work, provide an accurate horizon-scale flow structure for M87 and other active galactic nuclei (AGN), and isolate whether AGN feedback is driven by radiation or by an electromagnetic, thermal, or kinetic wind/jet. For example, the low radiative efficiency and weak BH spin-down rate from our simulation suggest that BH growth over cosmological times to billions of solar masses by redshifts of z ˜ 6-8 is achievable even with rapidly rotating BHs and 10 M? BH seeds.

McKinney, Jonathan C.; Tchekhovskoy, Alexander; Sadowski, Aleksander; Narayan, Ramesh

2014-07-01

276

Alignment Timescale of the Microquasar GRO J1655-40  

E-print Network

The microquasar GRO J1655-40 has a black hole with spin angular momentum apparently misaligned to the orbital plane of its companion star. We analytically model the system with a steady state disc warped by Lense-Thirring precession and find the timescale for the alignment of the black hole with the binary orbit. We make detailed stellar evolution models so as to estimate the accretion rate and the lifetime of the system in this state. The secondary can be evolving at the end of the main sequence or across the Hertzsprung gap. The mass-transfer rate is typically fifty times higher in the latter case but we find that, in both cases, the lifetime of the mass transfer state is at most a few times the alignment timescale. The fact that the black hole has not yet aligned with the orbital plane is therefore consistent with either model. We conclude that the system may or may not have been counter-aligned after its supernova kick but that it is most likely to be close to alignment rather than counteralignment now.

Rebecca G. Martin; Christopher A. Tout; J. E. Pringle

2008-02-26

277

Alignment Timescale of the Microquasar GRO J1655-40  

E-print Network

The microquasar GRO J1655-40 has a black hole with spin angular momentum apparently misaligned to the orbital plane of its companion star. We analytically model the system with a steady state disc warped by Lense-Thirring precession and find the timescale for the alignment of the black hole with the binary orbit. We make detailed stellar evolution models so as to estimate the accretion rate and the lifetime of the system in this state. The secondary can be evolving at the end of the main sequence or across the Hertzsprung gap. The mass-transfer rate is typically fifty times higher in the latter case but we find that, in both cases, the lifetime of the mass transfer state is at most a few times the alignment timescale. The fact that the black hole has not yet aligned with the orbital plane is therefore consistent with either model. We conclude that the system may or may not have been counter-aligned after its supernova kick but that it is most likely to be close to alignment rather than counteralignment now.

Martin, Rebecca G; Pringle, J E

2008-01-01

278

Stellar differential rotation and coronal time-scales  

NASA Astrophysics Data System (ADS)

We investigate the time-scales of evolution of stellar coronae in response to surface differential rotation and diffusion. To quantify this, we study both the formation time and lifetime of a magnetic flux rope in a decaying bipolar active region. We apply a magnetic flux transport model to prescribe the evolution of the stellar photospheric field, and use this to drive the evolution of the coronal magnetic field via a magnetofrictional technique. Increasing the differential rotation (i.e. decreasing the equator-pole lap time) decreases the flux rope formation time. We find that the formation time is dependent upon the lap time and the surface diffusion time-scale through the relation ?_Form ? ?{?_Lap?_Diff}. In contrast, the lifetimes of flux ropes are proportional to the lap time (?Life??Lap). With this, flux ropes on stars with a differential rotation of more than eight times the solar value have a lifetime of less than 2 d. As a consequence, we propose that features such as solar-like quiescent prominences may not be easily observable on such stars, as the lifetimes of the flux ropes which host the cool plasma are very short. We conclude that such high differential rotation stars may have very dynamical coronae.

Gibb, G. P. S.; Jardine, M. M.; Mackay, D. H.

2014-10-01

279

SYSTEMATIC UNCERTAINTIES IN THE SPECTROSCOPIC MEASUREMENTS OF NEUTRON-STAR MASSES AND RADII FROM THERMONUCLEAR X-RAY BURSTS. II. EDDINGTON LIMIT  

SciTech Connect

Time-resolved X-ray spectroscopy of thermonuclear bursts observed from low-mass X-ray binaries offer a unique tool to measure neutron-star masses and radii. In this paper, we continue our systematic analysis of all the X-ray bursts observed with Rossi X-ray Timing Explorer from X-ray binaries. We determine the events that show clear evidence for photospheric radius expansion and measure the Eddington limits for these accreting neutron stars using the bolometric fluxes attained at the touchdown moments of each X-ray burst. We employ a Bayesian technique to investigate the degree to which the Eddington limit for each source remains constant between bursts. We find that for sources with a large number of radius expansion bursts, systematic uncertainties are at a 5%-10% level. Moreover, in six sources with only pairs of Eddington-limited bursts, the distribution of fluxes is consistent with a {approx}10% fractional dispersion. This indicates that the spectroscopic measurements of neutron-star masses and radii using thermonuclear X-ray bursts can reach the level of accuracy required to distinguish between different neutron-star equations of state, provided that uncertainties related to the overall flux calibration of X-ray detectors are of comparable magnitude.

Guever, Tolga; Oezel, Feryal; Psaltis, Dimitrios [Department of Astronomy, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)

2012-03-01

280

Focus on quantum Einstein gravity Focus on quantum Einstein gravity  

NASA Astrophysics Data System (ADS)

The gravitational asymptotic safety program summarizes the attempts to construct a consistent and predictive quantum theory of gravity within Wilson's generalized framework of renormalization. Its key ingredient is a non-Gaussian fixed point of the renormalization group flow which controls the behavior of the theory at trans-Planckian energies and renders gravity safe from unphysical divergences. Provided that the fixed point comes with a finite number of ultraviolet-attractive (relevant) directions, this construction gives rise to a consistent quantum field theory which is as predictive as an ordinary, perturbatively renormalizable one. This opens up the exciting possibility of establishing quantum Einstein gravity as a fundamental theory of gravity, without introducing supersymmetry or extra dimensions, and solely based on quantization techniques that are known to work well for the other fundamental forces of nature. While the idea of gravity being asymptotically safe was proposed by Steven Weinberg more than 30 years ago [1], the technical tools for investigating this scenario only emerged during the last decade. Here a key role is played by the exact functional renormalization group equation for gravity, which allows the construction of non-perturbative approximate solutions for the RG-flow of the gravitational couplings. Most remarkably, all solutions constructed to date exhibit a suitable non-Gaussian fixed point, lending strong support to the asymptotic safety conjecture. Moreover, the functional renormalization group also provides indications that the central idea of a non-Gaussian fixed point providing a safe ultraviolet completion also carries over to more realistic scenarios where gravity is coupled to a suitable matter sector like the standard model. These theoretical successes also triggered a wealth of studies focusing on the consequences of asymptotic safety in a wide range of phenomenological applications covering the physics of black holes, early time cosmology and the big bang, as well as TeV-scale gravity models testable at the Large Hadron Collider. On different grounds, Monte-Carlo studies of the gravitational partition function based on the discrete causal dynamical triangulations approach provide an a priori independent avenue towards unveiling the non-perturbative features of gravity. As a highlight, detailed simulations established that the phase diagram underlying causal dynamical triangulations contains a phase where the triangulations naturally give rise to four-dimensional, macroscopic universes. Moreover, there are indications for a second-order phase transition that naturally forms the discrete analog of the non-Gaussian fixed point seen in the continuum computations. Thus there is a good chance that the discrete and continuum computations will converge to the same fundamental physics. This focus issue collects a series of papers that outline the current frontiers of the gravitational asymptotic safety program. We hope that readers get an impression of the depth and variety of this research area as well as our excitement about the new and ongoing developments. References [1] Weinberg S 1979 General Relativity, an Einstein Centenary Survey ed S W Hawking and W Israel (Cambridge: Cambridge University Press)

Ambjorn, Jan; Reuter, Martin; Saueressig, Frank

2012-09-01

281

Liver transplantation at Hospital Israelita Albert Einstein Transplante de fígado no Hospital Israelita Albert Einstein  

Microsoft Academic Search

Objective: To present patients and results of liver transplantation performed by the Liver Unit team at the Hospital Israelita Albert Einstein. Methods: The medical records of all patients transplanted by the team at the Liver Unit of the Hospital Israelita Albert Einstein, from January 2002 to June 2005, were analyzed. Results: During this period, 328 transplants were performed and 64.3%

Sergio Mies

282

Einstein und der Eötvös-Versuch: Ein Brief Albert Einsteins an Willy Wien  

Microsoft Academic Search

Das Aequivalenzprinzip wurde von Einstein erst 1907 in Worte gefasst. Er wendete sich 1912 brieflich an W. Wien mit der Bitte, den Unterschied der Schwingungsdauer eines Uranpendels und eines Bleipendels sowie die Proportionalität der trägen und schweren Massen eines Blei- und eines Urangewichts auszumessen, und zwar mit einer Drehwage. Der Brief macht es klar, dass Einstein bei der Aufstellung des

József Illy

1989-01-01

283

Timescales of texture development in a cooling lava dome  

NASA Astrophysics Data System (ADS)

Crystal growth and crack development in cooling lava domes are both capable of redistributing and mobilizing water. Cracking and hydration decrease the stability of a dome, which may lead to hazards including partial dome collapse and block and ash flows. By examining the distribution of water around crystals and cracks, we identify and confine temperature and timescales of texture development in glassy rocks of volcanic domes. Four generations of textures have been identified: type a: spherulites, type b: cracks associated with spherulite growth, type c: perlitic cracks, and type d: disparate cracks. High-resolution imaging using Fourier Transform Infrared Spectroscopy (FTIR) performed on samples from the Ngongotaha dome, New Zealand, show an increase in H2O of up to 450% along gradients of around 100 ?m up to 300 ?m in length from perlitic cracks, spherulitic cracks and in haloes around spherulites. No gradients in water concentrations across the disparate cracks are present. Water diffusion models show potential timescale-temperature couples that coincide with textural observations and previous studies, and allow us to develop a conceptual model of spherulite growth and cracking in a cooling lava dome. Spherulite growth starts around the glass transition temperature (Tg) when the viscous melt cools to a brittle solid and proceeds with cracking related to volume changes at slightly lower temperatures and shorter timescales (days to weeks) compared to spherulite growth. Perlitic cracking happens at T?Tg, allowing hydration of a permeable network within weeks to months. Low temperature (?50 °C) cracks could not be hydrated in the time since eruption (?230 ka). Our data show that textures in cooling glass develop during cooling below Tg within days, producing cracks and crystals that create inhomogeneities in the spatial distribution of water. The lengthscales of water diffusion away from spherulites, spherulite cracks, and perlite cracks suggest that most of the rehydration of melt/glass occurs at relatively high temperatures (>400 °C). Lack of evidence for water diffusion around other cracks suggests minor low-temperature meteoric water rehydration following emplacement.

von Aulock, F. W.; Nichols, A. R. L.; Kennedy, B. M.; Oze, C.

2013-08-01

284

Einstein's equivalence principle in cosmology  

NASA Astrophysics Data System (ADS)

We study physical consequences of the Einstein equivalence principle (EEP) for a Hubble observer in FLRW universe. We introduce the local inertial coordinates with the help of a special conformal transformation. The local inertial metric is Minkowski-flat and materialized by a congruence of time-like geodesics of static observers. The static observers are equipped with the ideal clocks measuring the proper time that is synchronized with the clocks of the Hubble observer. The local inertial metric is used for physical measurements of spacetime intervals with the ideal clocks and rulers. The special conformal transformation preserves null geodesics but does not keep invariant time-like geodesics. Moreover, it makes the rate of the local time coordinate dependent on velocity of the particle which makes impossible to rich the uniform parameterization of the world lines of static observers and light geodesics with a single parameter - they differ by the conformal factor of FLRW metric. It tells us that the metric on the light cone is not Minkowski-flat but depends on the scale factor of FLRW universe and it can be interpreted as a weak violation of EEP for photons. The importance of this violation for gravitational physics is that some of local experiments conducted with freely-propagating electromagnetic waves may be sensitive to the Hubble expansion. We show that the Hubble constant H can be measured within the solar system by means of high-precision spacecraft Doppler tracking as a blue shift of frequency of radio waves circulating in the Earth-spacecraft radio link. We also analyze the behavior of the standing wave in a microwave resonator and show that the standing wave is insensitive to the Hubble expansion.

Kopeikin, Sergei

285

Einstein's equivalence principle in cosmology  

E-print Network

We study physical consequences of the Einstein equivalence principle (EEP) for a Hubble observer in FLRW universe. We introduce the local inertial coordinates with the help of a special conformal transformation. The local inertial metric is Minkowski-flat and materialized by a congruence of time-like geodesics of static observers. The static observers are equipped with the ideal clocks measuring the proper time that is synchronized with the clocks of the Hubble observer. The local inertial metric is used for physical measurements of spacetime intervals with the ideal clocks and rulers. The special conformal transformation preserves null geodesics but does not keep invariant time-like geodesics. Moreover, it makes the rate of the local time coordinate dependent on velocity of the particle which makes impossible to rich the uniform parameterization of the world lines of static observers and light geodesics with a single parameter - they differ by the conformal factor of FLRW metric. It tells us that the metric on the light cone is not Minkowski-flat but depends on the scale factor of FLRW universe and it can be interpreted as a weak violation of EEP for photons. The importance of this violation for gravitational physics is that some of local experiments conducted with freely-propagating electromagnetic waves may be sensitive to the Hubble expansion. We show that the Hubble constant H can be measured within the solar system by means of high-precision spacecraft Doppler tracking as a blue shift of frequency of radio waves circulating in the Earth-spacecraft radio link. We also analyze the behavior of the standing wave in a microwave resonator and show that the standing wave is insensitive to the Hubble expansion.

Sergei M. Kopeikin

2013-11-19

286

Einstein's vierbein field theory of curved space  

E-print Network

General Relativity theory is reviewed following the vierbein field theory approach proposed in 1928 by Einstein. It is based on the vierbein field taken as the "square root" of the metric tensor field. Einstein's vierbein theory is a gauge field theory for gravity; the vierbein field playing the role of a gauge field but not exactly like the vector potential field does in Yang-Mills theory--the correction to the derivative (the covariant derivative) is not proportional to the vierbein field as it would be if gravity were strictly a Yang-Mills theory. Einstein discovered the spin connection in terms of the vierbein fields to take the place of the conventional affine connection. To date, one of the most important applications of the vierbein representation is for the derivation of the correction to a 4-spinor quantum field transported in curved space, yielding the correct form of the covariant derivative. Thus, the vierbein field theory is the most natural way to represent a relativistic quantum field theory in curved space. Using the vierbein field theory, presented is a derivation of the the Einstein equation and then the Dirac equation in curved space. Einstein's original 1928 manuscripts translated into English are included.

Jeffrey Yepez

2011-06-10

287

Timescales for Spindown on the Lower Main Sequence  

NASA Astrophysics Data System (ADS)

Recent work (Schussler & Solanki 1992; Caligari, Moreno-Insertis, & Schussler 1994; Buzasi 1997) has demonstrated that rapidly rotating stars should display polar magnetic activity due to the Coriolis effect. Buzasi (1997) has shown that this effect increases with lateness of spectral type, and is particularly pronounced for M stars. One important consequence of the predicted polar activity is the increase in spindown timescales for these stars, since corotation of the emerging wind will be most readily enforced at high latitudes, where angular momentum loss is less efficient. Using simple models, I derive approximate spindown times on the lower main sequence, taking the Coriolis effect into account, and compare these to previous estimates. In addition, I examine these results in light of recent observations of rotational periods of cluster stars.

Buzasi, Derek L.

288

From lifetime to evolution: timescales of human gut microbiota adaptation  

PubMed Central

Human beings harbor gut microbial communities that are essential to preserve human health. Molded by the human genome, the gut microbiota (GM) is an adaptive component of the human superorganisms that allows host adaptation at different timescales, optimizing host physiology from daily life to lifespan scales and human evolutionary history. The GM continuously changes from birth up to the most extreme limits of human life, reconfiguring its metagenomic layout in response to daily variations in diet or specific host physiological and immunological needs at different ages. On the other hand, the microbiota plasticity was strategic to face changes in lifestyle and dietary habits along the course of the recent evolutionary history, that has driven the passage from Paleolithic hunter-gathering societies to Neolithic agricultural farmers to modern Westernized societies. PMID:25408692

Quercia, Sara; Candela, Marco; Giuliani, Cristina; Turroni, Silvia; Luiselli, Donata; Rampelli, Simone; Brigidi, Patrizia; Franceschi, Claudio; Bacalini, Maria Giulia; Garagnani, Paolo; Pirazzini, Chiara

2014-01-01

289

Validating Computational Cognitive Process Models across Multiple Timescales  

NASA Astrophysics Data System (ADS)

Model comparison is vital to evaluating progress in the fields of artificial general intelligence (AGI) and cognitive architecture. As they mature, AGI and cognitive architectures will become increasingly capable of providing a single model that completes a multitude of tasks, some of which the model was not specifically engineered to perform. These models will be expected to operate for extended periods of time and serve functional roles in real-world contexts. Questions arise regarding how to evaluate such models appropriately, including issues pertaining to model comparison and validation. In this paper, we specifically address model validation across multiple levels of abstraction, using an existing computational process model of unmanned aerial vehicle basic maneuvering to illustrate the relationship between validity and timescales of analysis.

Myers, Christopher; Gluck, Kevin; Gunzelmann, Glenn; Krusmark, Michael

2010-12-01

290

Modes of embayed beach dynamics: analysis reveals emergent timescales  

NASA Astrophysics Data System (ADS)

Embayed beaches, or beaches positioned between rocky headlands, exhibit morphologic changes over many length and time scales. Beach sediment is transported as a result of the day-to-day wave forcing, causing patterns of erosion and accretion. We use the Rocky Coastline Evolution Model (RCEM) to investigate how patterns of shoreline change depend on wave climate (the distribution of wave-approach angles) and beach characteristics. Measuring changes in beach width through time allows us to track the evolution of the shape of the beach and the movement of sand within it. By using Principle Component Analysis (PCA), these changes can be categorized into modes, where the first few modes explain the majority of the variation in the time series. We analyze these modes and how they vary as a function of wave climate and headland/bay aspect ratio. In the purposefully simple RCEM, sediment transport is wave-driven and affected by wave shadowing behind the headlands. The rock elements in our model experiments (including the headlands) are fixed and unerodable so that this analysis can focus purely on sand dynamics between the headlands, without a sand contribution from the headlands or cliffs behind the beach. The wave climate is characterized by dictating the percentage of offshore waves arriving from the left and the percentage of waves arriving from high angles (very oblique to the coastline orientation). A high-angle dominated wave climate tends to amplify coastline perturbations, whereas a lower-angle wave climate is diffusive. By changing the headland/bay aspect ratio and wave climate, we can perform PCA analysis of generalized embayed beaches with differing anatomy and wave climate forcings. Previous work using PCA analysis of embayed beaches focused on specific locations and shorter timescales (<30 years; Short and Trembanis, 2004). By using the RCEM, we can more broadly characterize beach dynamics over longer timescales. The first two PCA modes, which explain a majority of the beach width time series variation (typically >70%), are a 'breathing' mode and a 'rotational' mode. The newly identified breathing mode captures the sand movement from the middle of the beach towards the edges (thickening the beach along the headlands), and the rotational mode describes the movement of sand towards one headland or another, both in response to stochastic fluctuations about the mean wave climate. The two main modes operate independently and on different timescales. In a weakly low-angle dominated wave climate, the breathing mode tends to be the first mode (capturing the most variance), but with greater low-angle dominance (greater morphological diffusivity), the rotational mode tends to be first. The aspect ratio of the bay also affects the order of the modes, because wave shadowing affects sediment transport behind the headlands. Previous work has attributed beach rotation to changes in various climate indices such as the North Atlantic Oscillation (Thomas et al., 2011); however, PCA analysis of the RCEM results suggests that embayed beaches can have characteristic timescales of sand movement that result from internal system dynamics, emerging even within a statistically constant wave climate. These results suggest that morphologic changes in embayed beaches can occur independently of readily identifiable shifts in forcing.

Murray, K. T.; Murray, A.; Limber, P. W.; Ells, K. D.

2013-12-01

291

Timescales for localized electron injections to become a thin shell  

NASA Astrophysics Data System (ADS)

Timescales for localized injections of electrons into the Earth's inner magnetosphere to spread into a thin shell are presented. The Radiation Belt Environment (RBE) model is used to numerically examine this topic, initializing the simulations with an MLT-confined Gaussian peak of electrons. Near the slot region, where the numerical experiments are conducted (L=3), the transition from a localized injection into a thin shell is driven by scattering with plasmaspheric hiss, shifting the energy and pitch angle of the particles, and ULF waves, shifting the radial location of the particles, all of which changes the drift speed. This mixing is energy dependent, taking much longer at the lower energies. It is shown that during static driving conditions it takes >3 hours for a narrow-MLT initial distribution of MeV-energy electrons to transform into a uniformly distributed ring, but takes more than 6 hours for < 300 keV electrons to achieve a thin shell state. During a magnetic storm interval, the timescale to reach a thin shell is somewhat shorter as the large-scale fluctuations of the magnetic field diffuse the particles in radial distance, enhancing the mixing. Interestingly, some parts of velocity space take longer with the magnetic fluctuations included, and the influence of the hiss scattering is modified as well. The implication is that localized injections, from the tail or from another source, do not become symmetric in local time for several hours, during which MLT-dependent interactions can play a significant role on the evolution and dynamics of the population.

Liemohn, Michael; Fok, Mei-Ching; Zheng, Qiuhua.; Xu, Shaosui

292

Tidal Disruption of Strengthless Rubble Piles--A Timescale Analysis  

NASA Astrophysics Data System (ADS)

The brief and dramatic appearance of Comet Shoemaker--Levy 9 (S--L 9) has punctuated the notion that many small members of the solar system might be strengthless `rubble-piles'. Models of the S--L 9 encounter indicate that only a relatively strengthless rubble-pile is able to catastrophically disrupt into a cloud of debris that later condenses into twenty or so gravitating `clumps' having the S--L 9 `string-of-pearls' morphology (e.g., Asphaug and Benz 1996). These models show that gravitational condensation of the debris into distinct clumps depends sensitively on the progenitor's density as well as its orbit. This phenomenon is re-examined by tracking the orbital motion andthe local mass density of a tidally disrupted projectile (see also Rettig et al. 1996). By employing elementary orbit mechanics, it is shown that when the debris' gravitational contraction timescale becomes shorter than its orbital spreading timescale, the debris breaks up into n L/D distinct clumps, where L is the debris length and D is the progenitor's diameter. Without appealing to a CPU--intensive calculation, we extend the available N--body simulations to unexplored regions of parameter space and reveal how the number of clumps n depends upon the progenitor's density, its periapse distance, and velocity at infinity (the problem is generalized to hyperbolic encounters as well). These findings also provide an additional constraint for the Galilean crater chain problem. We find that the projectile's responsible for the Gomul and Gipul crater chains on Callisto likely had comet--like densities of p<1 gm/cm(3) . However we are unable to distinguish between cometary and asteroidal impactors for the remaining chains which have fewer numbers of craters.

Rettig, T. W.; Hahn, J. M.; Ward, W. R.

1997-12-01

293

Tidal Disruption of Strengthless Rubble Piles---A Timescale Analysis  

NASA Astrophysics Data System (ADS)

The brief and dramatic appearance of Comet Shoemaker--Levy 9 (S--L 9) has punctuated the notion that many small members of the solar system might be strengthless `rubble-piles'. Models of the S--L 9 encounter indicate that only a relatively strengthless rubble-pile is able to catastrophically disrupt into a cloud of debris that later condenses into twenty or so gravitating `clumps' having the S--L 9 `string-of-pearls' morphology (e.g., Asphaug and Benz 1996). These models show that gravitational condensation of the debris into distinct clumps depends sensitively on the progenitor's density as well as its orbit. This phenomenon is re-examined by tracking the orbital motion and the local mass density of a tidally disrupted projectile (see also Rettig et al. 1996). By employing elementary orbit mechanics, it is shown that when the debris' gravitational contraction timescale becomes shorter than its orbital spreading timescale, the debris breaks up into n ~ L/D distinct clumps, where L is the debris length and D is the progenitor's diameter. Without appealing to a CPU--intensive calculation, we extend the available N--body simulations to unexplored regions of parameter space and reveal how the number of clumps n depends upon the progenitor's density, its periapse distance, and velocity at infinity (the problem is generalized to hyperbolic encounters as well). These findings also provide an additional constraint for the Galilean crater chain problem. We find that the projectile's responsible for the Gomul and Gipul crater chains on Callisto likely had comet--like densities of rho_0 ?1 gm/cm(3) . However we are unable to distinguish between cometary and asteroidal impactors for the remaining chains which have fewer numbers of craters.

Hahn, J. M.; Rettig, T. W.; Ward, W. R.

1997-07-01

294

Tidal Disruption of Strengthless Rubble Piles--A Timescale Analysis  

NASA Astrophysics Data System (ADS)

The brief and dramatic appearance of Comet Shoemaker--Levy 9 (S--L 9) has punctuated the notion that many small members of the solar system might be strengthless `rubble-piles'. Models of the S--L 9 encounter indicate that only a relatively strengthless rubble-pile is able to catastrophically disrupt into a cloud of debris that later condenses into twenty or so gravitating `clumps' having the S--L 9 `string-of-pearls' morphology (e.g., Asphaug and Benz 1996). These models show that gravitational condensation of the debris into distinct clumps depends sensitively on the progenitor's density as well as its orbit. This phenomenon is re-examined by tracking the orbital motion andthe local mass density of a tidally disrupted projectile (see also Rettig et al. 1996). By employing elementary orbit mechanics, it is shown that when the debris' gravitational contraction timescale becomes shorter than its orbital spreading timescale, the debris breaks up into n L/D distinct clumps, where L is the debris length and D is the progenitor's diameter. Without appealing to a CPU--intensive calculation, we extend the available N--body simulations to unexplored regions of parameter space and reveal how the number of clumps n depends upon the progenitor's density, its periapse distance, and velocity at infinity (the problem is generalized to hyperbolic encounters as well). These findings also provide an additional constraint for the Galilean crater chain problem. We find that the projectile's responsible for the Gomul and Gipul crater chains on Callisto likely had comet--like densities of p<1 gm/cm(3) . However we are unable to distinguish between cometary and asteroidal impactors for the remaining chains which have fewer numbers of craters.

Rettig, T.; Hahn, J.

1998-05-01

295

Coherence, Abstraction, and Personal Involvement: Albert Einstein, Physicist and Humanist.  

ERIC Educational Resources Information Center

Reviews Einstein's main contributions to physics, and analyzes the importance of a coherent body of theory. Einstein's involvement in nonscientific issues such as nuclear disarmament is also included. (HM)

Ne'eman, Yuval

1979-01-01

296

Buffer-Gas Cooled Bose-Einstein Condensate  

E-print Network

We report the creation of a Bose-Einstein condensate using buffer-gas cooling, the first realization of Bose-Einstein condensation using a broadly general method which relies neither on laser cooling nor unique atom-surface ...

Ketterle, Wolfgang

297

Einstein M.D. Program 20112012 applicant guide  

E-print Network

Einstein M.D. Program 2011­2012 applicant guide O F Y E S H I V A U N I V E R S I T Y Albert. tHe Big pictuRe tHe inSide StORY #12;MeSSage FROM tHe dean WelcOMe At Albert Einstein College of Medicine Einstein College of Medicine #12;2 Welcome Explore how Einstein can give you the skills to develop

Jenny, Andreas

298

Einstein M.D. Program 20132014 applicant guide  

E-print Network

Einstein M.D. Program 2013­2014 applicant guide O F Y E S H I V A U N I V E R S I T Y Albert and our accomplishments. tHe inSide StoRY #12;WelcoMe At Albert Einstein College of Medicine, compassion Einstein College of Medicine #12;2 Welcome Explore how Einstein can give you the skills to develop

Emmons, Scott

299

The EINSTEIN On-Line Service  

E-print Network

The Einstein On-Line Service (EOLS) is a simple menu-driven system which provides an intuitive method of querying over one hundred database catalogs. In addition, the EOLS contains over 30 CDROMs of images from the Einstein X-ray Observatory which are available for downloading. The EOLS provides all of our databases to the NASA Astrophysics Data System (ADS) and our documents which describe each table are written in the ADS format. In conjunction with the IAU working group on Radioastronomical Databases, the EOLS serves as an experimental platform for on-line access to radio source catalogs. The number of entries in these catalogs exceeds half a million.

D. E. Harris; C. S. Grant; H. Andernach

1994-11-05

300

Comment on "Scalar Einstein-Aether theory"  

E-print Network

A recent paper studies a modification of Einstein-aether theory in which the aether vector is restricted, at the level of the action, to be the gradient of a scalar. In this comment we note that this scalar version of Einstein-aether theory is equivalent to the projectable version of the IR limit of Ho\\v{r}ava gravity when the potential for the scalar is constant. This provides a generally covariant formulation for projectable Ho\\v{r}ava gravity.

Ted Jacobson; Antony J. Speranza

2014-05-25

301

Propagating torsion in the Einstein frame  

SciTech Connect

The Einstein-Cartan-Saa theory of torsion modifies the spacetime volume element so that it is compatible with the connection. The condition of connection compatibility gives constraints on torsion, which are also necessary for the consistence of torsion, minimal coupling, and electromagnetic gauge invariance. To solve the problem of positivity of energy associated with the torsionic scalar, we reformulate this theory in the Einstein conformal frame. In the presence of the electromagnetic field, we obtain the Hojman-Rosenbaum-Ryan-Shepley theory of propagating torsion with a different factor in the torsionic kinetic term.

Poplawski, Nikodem J. [Department of Physics, Indiana University, 727 East Third Street, Bloomington, Indiana 47405 (United States)

2006-11-15

302

Resonances for coupled Bose-Einstein condensates  

NASA Astrophysics Data System (ADS)

The properties of a Bose-Einstein condensate in a two-well potential can be manipulated by periodic modulation of the potential parameters. We study the effects arising from modulating the barrier height and the difference in well depth. At certain modulation frequencies the system exhibits resonances, which may show up in an enhancement of the tunneling rate between the wells. Resonances can be used to control the particle distribution over the wells. Some of the effects occurring in the two-well system also arise for a Bose-Einstein condensate in an optical lattice.

Haroutyunyan, H. L.; Nienhuis, G.

2004-12-01

303

Einstein - Peace Now!: Visions and Ideas  

NASA Astrophysics Data System (ADS)

Einstein was not only an extraordinary scientist, but also a person who faced his social responsibilities determinedly. The main focus of this book is put on topical articles by Scientific and Peace Nobel Prize laureates, prominent scientists and those committed to peace issues and justice, as well as citizens engagement for peace. Among the contributors are more than 10 Nobel Prize laureates, such as Mikhail Gorbachev, Walter Kohn, Joseph Rotblat, Alexander Ginzburg or Hans Bethe. This unique collection of intellectual thoughts on Einstein's vision of peace addresses a thoughtful, concerned and courageous audience, and was compiled to encourage and envision ways towards a more peaceful society.

Braun, Reiner; Krieger, David

2005-09-01

304

Collisions of Einstein-Conformal Scalar Waves  

E-print Network

A large class of solutions of the Einstein-conformal scalar equations in D=2+1 and D=3+1 is identified. They describe the collisions of asymptotic conformal scalar waves and are generated from Einstein-minimally coupled scalar spacetimes via a (generalized) Bekenstein transformation. Particular emphasis is given to the study of the global properties and the singularity structure of the obtained solutions. It is shown, that in the case of the absence of pure gravitational radiation in the initial data, the formation of the final singularity is not only generic, but is even inevitable.

C. Klim?{\\'?}k; P. Koln{\\'?}k

1992-12-18

305

Beyond Einstein: Exploring the Extreme Universe  

NASA Technical Reports Server (NTRS)

This paper will give an overview of the NASA Universe Division Beyond Einstein program. The Beyond Einstein program consists of a series of exploratory missions to investigate some of the most important and pressing problems in modern-day astrophysics - including searches for Dark Energy and studies of the earliest times in the universe, during the inflationary period after the Big Bang. A variety of new technologies are being developed both in the science instrumentation these missions will carry and in the spacecraft that will carry those instruments.

Barbier, Louis M.

2005-01-01

306

GENERALIZED KILLING SPINORS ON EINSTEIN MANIFOLDS ANDREI MOROIANU, UWE SEMMELMANN  

E-print Network

GENERALIZED KILLING SPINORS ON EINSTEIN MANIFOLDS ANDREI MOROIANU, UWE SEMMELMANN Abstract. We study generalized Killing spinors on compact Einstein manifolds with pos- itive scalar curvature. This problem is related to the existence of compact Einstein hyper- surfaces in manifolds with parallel spinors

Semmelmann, Uwe

307

ALBERT EINSTEIN COLLEGE OF MEDICINE COMMITTEE ON GRADUATE MEDICAL EDUCATION  

E-print Network

ALBERT EINSTEIN COLLEGE OF MEDICINE COMMITTEE ON GRADUATE MEDICAL EDUCATION POLICY POLICY on SEXUAL of residents in the programs sponsored by the Albert Einstein College of Medicine, have established employment that no employee is subjected to such conduct. Originated 9/05 Approved 10/05 1 N.B. The Albert Einstein College

Yates, Andrew

308

ALBERT EINSTEIN COLLEGE OF MEDICINE COMMITTEE ON GRADUATE MEDICAL EDUCATION  

E-print Network

ALBERT EINSTEIN COLLEGE OF MEDICINE COMMITTEE ON GRADUATE MEDICAL EDUCATION POLICY RESIDENT program sponsored by the Albert Einstein College of Medicine must assess resident performance and use to support the care of patients. 1 N.B. The Albert Einstein College of Medicine serves as the ACGME

Yates, Andrew

309

ALBERT EINSTEIN COLLEGE OF MEDICINE OF YESHIVA UNIVERSITY  

E-print Network

ALBERT EINSTEIN COLLEGE OF MEDICINE OF YESHIVA UNIVERSITY JACK AND PEARL RESNICK CAMPUS · 1300's Responsibility E-MAIL ­ peter.babin@einstein.yu.edu PHONE: (718) 430-2243 Dosimeter/Film Badge Request: Female: 1. Did the Employee/Student have a previous badge at Einstein? 2. Has the Employee

Emmons, Scott

310

ALBERT EINSTEIN COLLEGE OF MEDICINE COMMITTEE ON GRADUATE MEDICAL EDUCATION  

E-print Network

ALBERT EINSTEIN COLLEGE OF MEDICINE COMMITTEE ON GRADUATE MEDICAL EDUCATION POLICY POLICY approved in lieu of an additional COGME policy. Revised: Sept. 2004 N.B. The Albert Einstein College on Graduate Medical Education of the Albert Einstein College of Medicine has established written policies

Yates, Andrew

311

ALBERT EINSTEIN COLLEGE OF MEDICINE COMMITTEE ON GRADUATE MEDICAL EDUCATION  

E-print Network

ALBERT EINSTEIN COLLEGE OF MEDICINE COMMITTEE ON GRADUATE MEDICAL EDUCATION POLICY POLICY sponsored by the Albert Einstein College of Medicine must not be required to engage in "Moonlighting." 7 May 2002 N.B. The Albert Einstein College of Medicine serves as the ACGME-accredited Institutional

Yates, Andrew

312

Albert Einstein College of Medicine Center for Experimental Therapeutics  

E-print Network

Albert Einstein College of Medicine Center for Experimental Therapeutics A Bold New Initiative that afflict humanity. For more than five decades, the Albert Einstein College of Medicine has been one Bringing Hope and Help to Patients #12;Disease Target ID Assay Development HTS* Einstein Center

Kenny, Paraic

313

Albert Einstein In the spring of 1921, five  

E-print Network

Albert Einstein In the spring of 1921, five years after the appear- ance of his comprehensive paper Study, Albert Einstein toured the United States to help raise funds for the establishment of a Hebrew; the remaining three, more technical in nature, formed the rest of the book. In subsequent editions, Einstein

Landweber, Laura

314

ALBERT EINSTEIN COLLEGE OF MEDICINE COMMITTEE ON GRADUATE MEDICAL EDUCATION  

E-print Network

ALBERT EINSTEIN COLLEGE OF MEDICINE COMMITTEE ON GRADUATE MEDICAL EDUCATION POLICY POLICY), as the employers of residents in the programs sponsored by the Albert Einstein College of Medicine have established of LOA should be filed with the Office of GME. Revised May 2002 N.B. The Albert Einstein College

Yates, Andrew

315

ALBERT EINSTEIN COLLEGE OF MEDICINE OF YESHIVA UNIVERSITY  

E-print Network

ALBERT EINSTEIN COLLEGE OF MEDICINE OF YESHIVA UNIVERSITY JACK AND PEARL RESNICK CAMPUS · 1300: Mr/Ms , social security # , who is presently associated with the Albert Einstein College of Medicine radiation exposure records be released to the Albert Einstein College of Medicine's Radiation Safety Office

Emmons, Scott

316

ALBERT EINSTEIN COLLEGE OF MEDICINE COMMITTEE ON GRADUATE MEDICAL EDUCATION  

E-print Network

ALBERT EINSTEIN COLLEGE OF MEDICINE COMMITTEE ON GRADUATE MEDICAL EDUCATION POLICY POLICY), as the employers of residents in the programs sponsored by the Albert Einstein College of Medicine, have each Process Policies of the employing institution. Revised Sept. 2004 1 N.B. The Albert Einstein College

Yates, Andrew

317

ALBERT EINSTEIN COLLEGE OF MEDICINE COMMITTEE ON GRADUATE MEDICAL EDUCATION  

E-print Network

ALBERT EINSTEIN COLLEGE OF MEDICINE COMMITTEE ON GRADUATE MEDICAL EDUCATION POLICY POLICY for residents transferring to an other program. (Revised May 2002) 1 N.B. The Albert Einstein College on Graduate Medical Education of the Albert Einstein College of Medicine has established written policies

Yates, Andrew

318

Einstein M.D. Program 20142015 APPLICANT GUIDE  

E-print Network

Einstein M.D. Program 2014�2015 APPLICANT GUIDE O F Y E S H I V A U N I V E R S I T Y Albert research and our accomplishments. THE INSIDE STORY #12;WELCOME At Albert Einstein College of Medicine experiences available at Montefiore, the University Hospital and academic medical center for Albert Einstein

Emmons, Scott

319

Albert Einstein College of Medicine Global Health Center  

E-print Network

Albert Einstein College of Medicine Global Health Center Complete and send to Denise Giocondo at that the funds being sent to the account indicated above belong to Albert Einstein College of Medicine: denise.giocondo@einstein.yu.edu Request to wire funds internationally: Name

Yates, Andrew

320

Albert Einstein College of Medicine of Yeshiva University  

E-print Network

4 1 Strategic Research Plan Albert Einstein College of Medicine of Yeshiva University Jack and Pearl Resnick Campus 1300 Morris Park Avenue Bronx, New York 10461 Albert Einstein College of Medicine.A. Cissell Consulting Design: GRAPHIC ARTS CENTER Creative Director: Peter Dama Albert Einstein College

Emmons, Scott

321

EINSTEINSpring 2007 spring 2007 I EinstEin  

E-print Network

: A publication for faculty, students, alumni, friends and supporters of the Albert einstein College of Medicine that cover the full spectrum of research currently performed by faculty of the Albert einstein College;spring 2007 I EinstEin eInSTeInCONTENTs 3 A meSSAge from the deAn 4 Children with AidS: the remarkable

Yates, Andrew

322

Einstein 2013-2014 Edition Student to Student  

E-print Network

. This guide does not represent the policies of the Albert Einstein College of Medicine or its affiliated, sexual orientation, or citi- zenship status. Upon hearing of this, Albert Einstein wrote a letter, March 14, 1953, Albert Einstein agreed to lend his name to the medi- cal school, the only institution

Yates, Andrew

323

Conceptual Development of Einstein's Mass-Energy Relationship  

ERIC Educational Resources Information Center

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…

Wong, Chee Leong; Yap, Kueh Chin

2005-01-01

324

Book Review: A. P. French (ed.): "Einstein: A Centenary Volume" and Gerald Tauber (ed.): "Albert Einstein's Theory of General Relativity"  

E-print Network

A. P. French (ed.): Einstein: A Centenary Volume. Pp. v > 332. Cambridge, Massachusetts: Harvard University Press, 1979. Cloth, $20.00. GeraJd Tauber (ed.): Albert Einstein's Theory of Cenerai Relativity. Pp. 6 + 351. New York: Crown Publishers..., 1979. Cloth, $14.95. Joe D. Van Zandt Theie is much irony in the publication of memorial volumes in honor of Albert Einstein. Einstein repeatedly showed astonishment at the celebrity status his work had brought and often made gently rebuking...

Van Zandt, Joe D.

1979-11-01

325

Einstein@Home all-sky search for periodic gravitational waves in LIGO S5 data  

E-print Network

This paper presents results of an all-sky searches for periodic gravitational waves in the frequency range [50, 1190] Hz and with frequency derivative ranges of [-2 x 10^-9, 1.1 x 10^-10] Hz/s for the fifth LIGO science run (S5). The novelty of the search lies in the use of a non-coherent technique based on the Hough-transform to combine the information from coherent searches on timescales of about one day. Because these searches are very computationally intensive, they have been deployed on the Einstein@Home distributed computing project infrastructure. The search presented here is about a factor 3 more sensitive than the previous Einstein@Home search in early S5 LIGO data. The post-processing has left us with eight surviving candidates. We show that deeper follow-up studies rule each of them out. Hence, since no statistically significant gravitational wave signals have been detected, we report upper limits on the intrinsic gravitational wave amplitude h0. For example, in the 0.5 Hz-wide band at 152.5 Hz, we can exclude the presence of signals with h0 greater than 7.6 x 10^-25 with a 90% confidence level.

J. Aasi; J. Abadie; B. P. Abbott; R. Abbott; T. D. Abbott; M. Abernathy; T. Accadia; F. Acernese; C. Adams; T. Adams; P. Addesso; R. Adhikari; C. Affeldt; M. Agathos; K. Agatsuma; P. Ajith; B. Allen; A. Allocca; E. Amador Ceron; D. Amariutei; S. B. Anderson; W. G. Anderson; K. Arai; M. C. Araya; S. Ast; S. M. Aston; P. Astone; D. Atkinson; P. Aufmuth; C. Aulbert; B. E. Aylott; S. Babak; P. Baker; G. Ballardin; S. Ballmer; Y. Bao; J. C. B. Barayoga; D. Barker; F. Barone; B. Barr; L. Barsotti; M. Barsuglia; M. A. Barton; I. Bartos; R. Bassiri; M. Bastarrika; A. Basti; J. Batch; J. Bauchrowitz; Th. S. Bauer; M. Bebronne; D. Beck; B. Behnke; M. Bejger; M. G. Beker; A. S. Bell; C. Bell; I. Belopolski; M. Benacquista; J. M. Berliner; A. Bertolini; J. Betzwieser; N. Beveridge; P. T. Beyersdorf; T. Bhadbade; I. A. Bilenko; G. Billingsley; J. Birch; R. Biswas; M. Bitossi; M. A. Bizouard; E. Black; J. K. Blackburn; L. Blackburn; D. Blair; B. Bland; M. Blom; O. Bock; T. P. Bodiya; C. Bogan; C. Bond; R. Bondarescu; F. Bondu; L. Bonelli; R. Bonnand; R. Bork; M. Born; V. Boschi; S. Bose; L. Bosi; B. Bouhou; S. Braccini; C. Bradaschia; P. R. Brady; V. B. Braginsky; M. Branchesi; J. E. Brau; J. Breyer; T. Briant; D. O. Bridges; A. Brillet; M. Brinkmann; V. Brisson; M. Britzger; A. F. Brooks; D. A. Brown; T. Bulik; H. J. Bulten; A. Buonanno; J. Burguet--Castell; D. Buskulic; C. Buy; R. L. Byer; L. Cadonati; G. Cagnoli; G. Cagnoli; E. Calloni; J. B. Camp; P. Campsie; K. Cannon; B. Canuel; J. Cao; C. D. Capano; F. Carbognani; L. Carbone; S. Caride; S. Caudill; M. Cavaglià; F. Cavalier; R. Cavalieri; G. Cella; C. Cepeda; E. Cesarini; T. Chalermsongsak; P. Charlton; E. Chassande-Mottin; W. Chen; X. Chen; Y. Chen; A. Chincarini; A. Chiummo; H. S. Cho; J. Chow; N. Christensen; S. S. Y. Chua; C. T. Y. Chung; S. Chung; G. Ciani; F. Clara; D. E. Clark; J. A. Clark; J. H. Clayton; F. Cleva; E. Coccia; P. -F. Cohadon; C. N. Colacino; A. Colla; M. Colombini; A. Conte; R. Conte; D. Cook; T. R. Corbitt; M. Cordier; N. Cornish; A. Corsi; C. A. Costa; M. Coughlin; J. -P. Coulon; P. Couvares; D. M. Coward; M. Cowart; D. C. Coyne; J. D. E. Creighton; T. D. Creighton; A. M. Cruise; A. Cumming; L. Cunningham; E. Cuoco; R. M. Cutler; K. Dahl; M. Damjanic; S. L. Danilishin; S. D'Antonio; K. Danzmann; V. Dattilo; B. Daudert; H. Daveloza; M. Davier; E. J. Daw; R. Day; T. Dayanga; R. De Rosa; D. DeBra; G. Debreczeni; J. Degallaix; W. Del Pozzo; T. Dent; V. Dergachev; R. DeRosa; S. Dhurandhar; L. Di Fiore; A. Di Lieto; I. Di Palma; M. Di Paolo Emilio; A. Di Virgilio; M. Díaz; A. Dietz; A. Dietz; F. Donovan; K. L. Dooley; S. Doravari; S. Dorsher; M. Drago; R. W. P. Drever; J. C. Driggers; Z. Du; J. -C. Dumas; S. Dwyer; T. Eberle; M. Edgar; M. Edwards; A. Effler; P. Ehrens; G. Endröczi; R. Engel; T. Etzel; K. Evans; M. Evans; T. Evans; M. Factourovich; V. Fafone; S. Fairhurst; B. F. Farr; M. Favata; D. Fazi; H. Fehrmann; D. Feldbaum; I. Ferrante; F. Ferrini; F. Fidecaro; L. S. Finn; I. Fiori; R. P. Fisher; R. Flaminio; S. Foley; E. Forsi; N. Fotopoulos; J. -D. Fournier; J. Franc; S. Franco; S. Frasca; F. Frasconi; M. Frede; M. A. Frei; Z. Frei; A. Freise; R. Frey; T. T. Fricke; D. Friedrich; P. Fritschel; V. V. Frolov; M. -K. Fujimoto; P. J. Fulda; M. Fyffe; J. Gair; M. Galimberti; L. Gammaitoni; J. Garcia; F. Garufi; M. E. Gáspár; G. Gelencser; G. Gemme; E. Genin; A. Gennai; L. Á. Gergely; S. Ghosh; J. A. Giaime; S. Giampanis; K. D. Giardina; A. Giazotto; S. Gil-Casanova; C. Gill; J. Gleason; E. Goetz; G. González; M. L. Gorodetsky; S. Goßler; R. Gouaty; C. Graef; P. B. Graff; M. Granata; A. Grant; C. Gray; R. J. S. Greenhalgh; A. M. Gretarsson; C. Griffo; H. Grote; K. Grover; S. Grunewald; G. M. Guidi; C. Guido; R. Gupta; E. K. Gustafson; R. Gustafson; J. M. Hallam; D. Hammer; G. Hammond; J. Hanks; C. Hanna; J. Hanson; J. Harms; G. M. Harry; I. W. Harry; E. D. Harstad; M. T. Hartman; K. Haughian; K. Hayama; J. -F. Hayau; J. Heefner; A. Heidmann; H. Heitmann; P. Hello; M. A. Hendry; I. S. Heng; A. W. Heptonstall; V. Herrera; M. Heurs; M. Hewitson; S. Hild; D. Hoak; K. A. Hodge; K. Holt; M. Holtrop; T. Hong; S. Hooper; J. Hough; E. J. Howell; B. Hughey; S. Husa; S. H. Huttner; T. Huynh-Dinh; D. R. Ingram; R. Inta; T. Isogai; A. Ivanov; K. Izumi; M. Jacobson; E. James; Y. J. Jang; P. Jaranowski; E. Jesse; W. W. Johnson; D. I. Jones; R. Jones; R. J. G. Jonker; L. Ju; P. Kalmus; V. Kalogera; S. Kandhasamy; G. Kang; J. B. Kanner; M. Kasprzack; R. Kasturi; E. Katsavounidis; W. Katzman; H. Kaufer; K. Kaufman; K. Kawabe; S. Kawamura; F. Kawazoe; D. Keitel; D. Kelley; W. Kells; D. G. Keppel; Z. Keresztes; A. Khalaidovski; F. Y. Khalili; E. A. Khazanov; B. K. Kim; C. Kim; H. Kim; K. Kim; N. Kim; Y. M. Kim; P. J. King; D. L. Kinzel; J. S. Kissel; S. Klimenko; J. Kline; K. Kokeyama; V. Kondrashov; S. Koranda; W. Z. Korth; I. Kowalska

2012-07-31

326

Can you do quantum mechanics without Einstein?  

E-print Network

The present form of quantum mechanics is based on the Copenhagen school of interpretation. Einstein did not belong to the Copenhagen school, because he did not believe in probabilistic interpretation of fundamental physical laws. This is the reason why we are still debating whether there is a more deterministic theory. One cause of this separation between Einstein and the Copenhagen school could have been that the Copenhagen physicists thoroughly ignored Einstein's main concern: the principle of relativity. Paul A. M. Dirac was the first one to realize this problem. Indeed, from 1927 to 1963, Paul A. M. Dirac published at least four papers to study the problem of making the uncertainty relation consistent with Einstein's Lorentz covariance. It is interesting to combine those papers by Dirac to make the uncertainty relation consistent with relativity. It is shown that the mathematics of two coupled oscillators enables us to carry out this job. We are then led to the question of whether the concept of localized probability distribution is consistent with Lorentz covariance.

Y. S. Kim; Marilyn E. Noz

2006-09-17

327

Can you do quantum mechanics without Einstein?  

SciTech Connect

The present form of quantum mechanics is based on the Copenhagen school of interpretation. Einstein did not belong to the Copenhagen school, because he did not believe in probabilistic interpretation of fundamental physical laws. This is the reason why we are still debating whether there is a more deterministic theory. One cause of this separation between Einstein and the Copenhagen school could have been that the Copenhagen physicists thoroughly ignored Einstein's main concern: the principle of relativity. Paul A. M. Dirac was the first one to realize this problem. Indeed, from 1927 to 1963, Paul A. M. Dirac published at least four papers to study the problem of making the uncertainty relation consistent with Einstein's Lorentz covariance. It is interesting to combine those papers by Dirac to make the uncertainty relation consistent with relativity. It is shown that the mathematics of two coupled oscillators enables us to carry out this job. We are then led to the question of whether the concept of localized probability distribution is consistent with Lorentz covariance.

Kim, Y. S. [Department of Physics, University of Maryland, College Park, Maryland 20742 (United States); Noz, Marilyn E. [Department of Radiology, New York University, New York, New York 10016 (United States)

2007-02-21

328

Cylindrical--spherical Einstein--Maxwell solitons  

Microsoft Academic Search

We present an analysis of a family of exact solutions of the Einstein--Maxwell equations, obtained using Alekseev's inverse scattering method. The solutions are simple soliton transformations of a Minkowski background and can be interpreted as cylindrical--spherical electrogravitational waves travelling on a flat background. Although the solutions are locally everywhere regular, the construction of a complete manifold (through appropriate extensions) requires

Reinaldo J. Gleiser; Carlos O. Nicasio; Alexander Garate

1994-01-01

329

New Information about Albert Einstein's Brain  

PubMed Central

In order to glean information about hominin (or other) brains that no longer exist, details of external neuroanatomy that are reproduced on endocranial casts (endocasts) from fossilized braincases may be described and interpreted. Despite being, of necessity, speculative, such studies can be very informative when conducted in light of the literature on comparative neuroanatomy, paleontology, and functional imaging studies. Albert Einstein's brain no longer exists in an intact state, but there are photographs of it in various views. Applying techniques developed from paleoanthropology, previously unrecognized details of external neuroanatomy are identified on these photographs. This information should be of interest to paleoneurologists, comparative neuroanatomists, historians of science, and cognitive neuroscientists. The new identifications of cortical features should also be archived for future scholars who will have access to additional information from improved functional imaging technology. Meanwhile, to the extent possible, Einstein's cerebral cortex is investigated in light of available data about variation in human sulcal patterns. Although much of his cortical surface was unremarkable, regions in and near Einstein's primary somatosensory and motor cortices were unusual. It is possible that these atypical aspects of Einstein's cerebral cortex were related to the difficulty with which he acquired language, his preference for thinking in sensory impressions including visual images rather than words, and his early training on the violin. PMID:19597545

Falk, Dean

2009-01-01

330

Einstein-Yang-Mills theory: Asymptotic symmetries  

NASA Astrophysics Data System (ADS)

Asymptotic symmetries of the Einstein-Yang-Mills system with or without cosmological constant are explicitly worked out in a unified manner. In agreement with a recent conjecture, one finds a Virasoro-Kac-Moody type algebra not only in three dimensions but also in the four-dimensional asymptotically flat case.

Barnich, Glenn; Lambert, Pierre-Henry

2013-11-01

331

Some general new Einstein Walker manifolds  

E-print Network

In this paper, Lie symmetry group method is applied to find the lie point symmetries group of a PDE system that is determined general form of four-dimensional Einstein Walker manifold. Also we will construct the optimal system of one-dimensional Lie subalgebras and investigate some of its group invariant solutions.

Mehdi Nadjafikhah; Mehdi Jafari

2012-06-17

332

Newton, forgive me . . . Albert Einstein, Autobiographical Notes  

E-print Network

Newton, forgive me . . . ­Albert Einstein, Autobiographical Notes d. graham burnett: Peter, in 1997 paper on special relativity­the paper that shook the foundations of Newton- ian physics­lies a `thought- mountable challenges to Newton's notion of absolute time (and absolute space). This we knew

Galison, Peter L.

333

The Infinite Universe of Einstein and Newton  

Microsoft Academic Search

Einstein's field equations for general relativity are solved for a static, phinfinite, isotropic and homogeneous Universe. One of the three solutions found, the ``infinite closed universe'', is shown to fit the data for the Hubble diagram better than the Big Bang model. Using general relativity, the force of gravity between two point particles is found. Utilizing this force and the

Barry Bruce

2003-01-01

334

On supersymmetric Einstein-Weyl spaces  

E-print Network

We use techniques developed for the classification of supersymmetric solutions to find Einstein-Weyl metrics with Lorentzian signature in arbitrary dimensions. We find that all supersymmetric timelike solutions are equivalent to a Lorentzian spacetime admitting a Killing spinor. Null supersymmetric solutions exhibit a Kundt-wave character.

Meessen, P; Palomo-Lozano, A

2011-01-01

335

Newton to Einstein: The Trail of Light  

Microsoft Academic Search

This engaging text takes the reader along the trail of light from Newton's particles to Einstein's relativity. Like the best detective stories, it presents clues and encourages the reader to draw conclusions before the answers are revealed. The first seven chapters cover the behavior of light, Newton's particle theory, waves and an electromagnetic wave theory of light, the photon, and

Ralph Baierlein

2001-01-01

336

Conformal anomalies on Einstein spaces with Boundary  

E-print Network

The anomalous rescaling for antisymmetric tensor fields, including gauge bosons, and Dirac fermions on Einstein spaces with boundary has been prone to errors and these are corrected here. The explicit calculations lead to some interesting identities that indicate a deeper underlying structure.

Ian G. Moss; Stephen J. Poletti

1994-05-21

337

Bose Einstein condensation on inhomogeneous amenable graphs  

Microsoft Academic Search

We investigate the Bose-Einstein Condensation on nonhomogeneous amenable networks for the model describing arrays of Josephson junctions. The resulting topological model, whose Hamiltonian is the pure hopping one given by the opposite of the adjacency operator, has also a mathematical interest in itself. We show that for the nonhomogeneous networks like the comb graphs, particles condensate in momentum and configuration

Francesco Fidaleo; Daniele Guido; Tommaso Isola

2008-01-01

338

Einstein Slew Survey: Data analysis innovations  

NASA Technical Reports Server (NTRS)

Several new methods were needed in order to make the Einstein Slew X-ray Sky Survey. The innovations which enabled the Slew Survey to be done are summarized. These methods included experimental approach to large projects, parallel processing on a LAN, percolation source detection, minimum action identifications, and rapid dissemination of the whole data base.

Elvis, Martin S.; Plummer, David; Schachter, Jonathan F.; Fabbiano, G.

1992-01-01

339

Einstein Observations of Galactic supernova remnants  

NASA Technical Reports Server (NTRS)

This paper summarizes the observations of Galactic supernova remnants with the imaging detectors of the Einstein Observatory. X-ray surface brightness contours of 47 remnants are shown together with gray-scale pictures. Count rates for these remnants have been derived and are listed for the HRI, IPC, and MPC detectors.

Seward, Frederick D.

1990-01-01

340

Albert Einstein and the Quantum Riddle  

ERIC Educational Resources Information Center

Derives a systematic structure contributing to the solution of the quantum riddle in Einstein's sense by deducing quantum mechanics from the postulates of symmetry, correspondence, and covariance. Indicates that the systematic presentation is in agreement with quantum mechanics established by Schroedinger, Born, and Heisenberg. (CC)

Lande, Alfred

1974-01-01

341

How Einstein Got the Nobel Prize.  

ERIC Educational Resources Information Center

Discusses why the Nobel Committee for Physics waited so long before giving Einstein the Nobel Prize and why they did not award it for relativity, but for the photoelectric effect instead. Focuses on the judgments of leading scientists who made nominations as well as committee members' decisions. (Author/JN)

Pais, Abraham

1982-01-01

342

Einstein's Viscous Advice Flowed Freely Nonetheless  

Microsoft Academic Search

This talk will examine a 1930 letter from Einstein to a medicinal chemistry assistant in Leiden, whose full name isn't identified in the text. I have ascertained that the letter was likely addressed to a student named Jan Lens who was writing his doctoral thesis in Utrecht on the properties of lyophilic colloids. I show how the letter refers to

Paul Halpern

2007-01-01

343

Rotating elastic bodies in Einstein gravity  

E-print Network

We prove that, given a stress-free, axially symmetric elastic body, there exists, for sufficiently small values of the gravitational constant and of the angular frequency, a unique stationary axisymmetric solution to the Einstein equations coupled to the equations of relativistic elasticity with the body performing rigid rotations around the symmetry axis at the given angular frequency.

Lars Andersson; Robert Beig; Bernd Schmidt

2008-11-06

344

Local extendability of Einstein vacuum manifolds  

E-print Network

We revisit in this article results of Klainerman and Rodnianski on a geometric breakdown criterion for Einstein vacuum spacetimes. We take advantage of the use of a time-harmonic transversal gauge to give a localized version (in space and time) of this result.

David Parlongue

2011-07-03

345

Einstein's Real ``Biggest Blunder'' Homer G. Ellis  

E-print Network

, proceeded to introduce as the material source term in his field equations ``a corresponding energy of gravitating matter, in analogy to the extension of the Laplace equation # 2 # = 0 for the vacuum gravitational mass, and the special theory identifies inertial mass with energy via E = mc 2 . When Einstein

Ellis, Homer

346

Einstein's Real "Biggest Blunder" Homer G. Ellis  

E-print Network

to introduce as the material source term in his field equations "a corresponding energy-tensor of matter of gravitating matter, in analogy to the extension of the Laplace equation 2 = 0 for the vacuum gravitational mass, and the special theory identifies inertial mass with energy via E = mc2 . When Einstein

Ellis, Homer

347

The Einstein All-Sky Slew Survey  

NASA Technical Reports Server (NTRS)

The First Einstein IPC Slew Survey produced a list of 819 x-ray sources, with f(sub x) approximately 10(exp -12) - 10(exp -10) erg/sq cm s and positional accuracy of approximately 1.2 feet (90 percent radius). The aim of this program was to identify these x-ray sources.

Elvis, Martin S.

1992-01-01

348

Fidelity of a Bose–Einstein condensates  

Microsoft Academic Search

We investigate fidelity for the quantum evolution of a Bose–Einstein condensate and reveal its general property with a simple model. We find the fidelity decay with time in various ways depending on the form of initial states as well as on mean-field dynamics. When the initial state is a coherent state, the fidelity decays with time in the ways of

Jie Liu; Wenge Wang; Chuanwei Zhang; Qian Niu; Baowen Li

2006-01-01

349

Dynamics of Bose-Einstein Condensates  

E-print Network

We report on some recent results concerning the dynamics of Bose-Einstein condensates, obtained in a series of joint papers with L. Erdos and H.-T. Yau. Starting from many body quantum dynamics, we present a rigorous derivation of a cubic nonlinear Schroedinger equation known as the Gross-Pitaevskii equation for the time evolution of the condensate wave function.

Benjamin Schlein

2007-04-05

350

Soliton resonance in bose-einstein condensate  

NASA Technical Reports Server (NTRS)

A new phenomenon in nonlinear dispersive systems, including a Bose-Einstein Condensate (BEC), has been described. It is based upon a resonance between an externally induced soliton and 'eigen-solitons' of the homogeneous cubic Schrodinger equation. There have been shown that a moving source of positive /negative potential induces bright /dark solitons in an attractive / repulsive Bose condensate.

Zak, Michail; Kulikov, I.

2002-01-01

351

Multiple timescale calculations of sawteeth in tokamak plasmas  

NASA Astrophysics Data System (ADS)

We present results of using M3D-C^1 [1] to perform 3D nonlinear magnetohydrodynamics calculations of a tokamak plasma that span the timescales associated with ideal and resistive stability as well as parallel and perpendicular transport. We specify the transport coefficients and apply a ``current controller'' that adjusts the boundary loop-voltage to keep the total plasma current fixed. Depending on the transport model, the plasma either reaches a stationary quasi-helical state in which the central safety factor is approximately unity, or it periodically undergoes sawtooth oscillations [2] with a period that approaches a constant value. These calculations have been performed both in a ``fixed boundary'' configuration with a wall on the plasma boundary as well as in a ``free boundary'' configuration with a separatrix surrounded by a scrape-off-layer plasma with open field lines and a resistive wall. We have performed series of runs to determine the dependence of the sequence on the form and magnitude of the resistivity, parallel and cross-field thermal conductivity, and viscosity. We are presently investigating the effect of the plasma shape on the sawtooth behavior, and the effects of two-fluid terms on the dynamics. [4pt] [1] J. Breslau, N. Ferraro, S. Jardin, Physics of Plasmas 16 092503 (2009) [0pt] [2] X. von Goeler, W. Stodiek, and N. Sauthoff, Phys. Rev. Lett. 33, 1201 (1974)

Jardin, S. C.; Ferraro, N.; Breslau, J.; Chen, J.

2011-11-01

352

RAS Awards and Prizes: RAS Awards 2009; Gold Medal: Prof. David Williams; Gold Medal: Prof. Eric Priest; Price Medal: Prof. Malcolm Sambridge; Eddington Medal: Prof. James Pringle  

NASA Astrophysics Data System (ADS)

Each year the RAS recognizes outstanding achievement in astronomy and geophysics by the award of medals and prizes. Candidates are nominated by Fellows and the awards made by a committee of Fellows, ensuring that these scientists have earned the respect and admiration of their peers in the research community. The Gold Medal for Astronomy is awarded to Prof. David Williams of University College London. The Gold Medal for Geophysics is awarded to Prof. Eric Priest of the University of St Andrews. The Price Medal is awarded to Prof. Malcolm Sambridge of the Australian National University. The Eddington Medal is given to Prof. James Pringle of the University of Cambridge.

2009-02-01

353

A MODEL FOR THE CORRELATION OF HARD X-RAY INDEX WITH EDDINGTON RATIO IN BLACK HOLE X-RAY BINARIES  

SciTech Connect

Observations show that there is a positive correlation between the Eddington ratio {lambda} and hard X-ray index {Gamma} for {lambda} {approx}> 0.01, and there is an anti-correlation between {lambda} and {Gamma} for {lambda} {approx}< 0.01 in black hole X-ray binaries (with {lambda} = L {sub bol}/L {sub Edd}). In this work, we theoretically investigate the correlation between {Gamma} and {lambda} within the framework of a disk-corona model. We improve the model by taking into account all cooling processes, including synchrotron and self-Compton radiations in the corona, Comptonization of the soft photons from the underlying accretion disk, and the bremsstrahlung radiations. Presuming that the coronal flow above the disk can reach up to the 0.1 Eddington rate at the outer region, we calculate the structure of the two-phase accretion flows and the emergent spectra for accretion rates from 0.003 to 0.1. We find that at accretion rates larger than bsim0.01 Eddington rate, a fraction of coronal gas condenses into the disk and an inner disk can be sustained by condensation. In this case, the X-ray emission is dominated by the scattering of the soft photon from the underlying disk in the corona. The emission from the inner disk and corona can produce the positive correlation between {lambda} and {Gamma}. While at accretion rates lower than bsim0.01 Eddington accretion rate, the inner disk vanishes completely by evaporation, and the accretion is dominated by advection-dominated accretion flows (ADAFs), in which the X-ray emission is produced by the Comptonization of the synchrotron and bremsstrahlung photons of ADAF itself. The emission from ADAFs can produce the anti-correlation between {lambda} and {Gamma}. We show that our model can roughly explain the observed evolution of {Gamma}{sub 3-25keV} with L {sub 0.5-25keV}/L {sub Edd} for the black hole X-ray transient H1743-322 in the decay of 2003 from the thermal-dominated state to low/hard state.

Qiao, Erlin; Liu, B. F., E-mail: qiaoel@nao.cas.cn [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

2013-02-10

354

Einstein and a century of time  

NASA Astrophysics Data System (ADS)

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 G??2 approx 1, where ? is the density of the Universe at time ?. 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 ?=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 U

Raine, D. J.

2005-09-01

355

On Einstein clusters as galactic dark matter halos  

E-print Network

We consider global and gravitational lensing properties of the recently suggested Einstein clusters of WIMPs as galactic dark matter halos. Being tangential pressure dominated, Einstein clusters are strongly anisotropic systems which can describe any galactic rotation curve by specifying the anisotropy. Due to this property, Einstein clusters may be considered as dark matter candidates. We analyse the stability of the Einstein clusters against both radial and non-radial pulsations, and we show that the Einstein clusters are dynamically stable. With the use of the Buchdahl type inequalities for anisotropic bodies, we derive upper limits on the velocity of the particles defining the cluster. These limits are consistent with those obtained from stability considerations. The study of light deflection shows that the gravitational lensing effect is slightly smaller for the Einstein clusters, as compared to the singular isothermal density sphere model for dark matter. Therefore lensing observations may discriminate, at least in principle, between Einstein cluster and other dark matter models.

C. G. Boehmer; T. Harko

2007-05-12

356

Biographies of Albert Einstein -- Mastermind of Theoretical Physics  

E-print Network

Over the years many have written biographies of Einstein. They all based their biographies on primary sources, archival material: memories and letters of people who were in contact with Einstein, Einstein's own recollections; interviews that Einstein had given over the years, and letters of Einstein to his friends - youth friends like Marcel Grossman and Michele Besso and later friends and colleagues like Heinrich Zangger; and especially his love letters with Mileva Mari\\'c. One can demarcate between two types of biographies, namely, Documentary biographies, and, Non-documentary biographies. Non-documentary biographies were written by people who based themselves on documentary biographies and on other non-documentary biographies. Documentary biographies were written by people who knew Einstein personally, and received information from him and from other people who were in personal contact with him. This type can be further divided into two subgroups: books that were written while Einstein was still alive, and...

Weinstein, Galina

2012-01-01

357

Ocean-atmosphere partitioning of anthropogenic carbon dioxide on centennial timescales  

E-print Network

approach for representing the partitioning of fossil fuel carbon dioxide in climate and earth systemOcean-atmosphere partitioning of anthropogenic carbon dioxide on centennial timescales Philip-atmosphere partitioning of anthropogenic carbon dioxide on centennial timescales is presented. The partial pressure

Follows, Mick

358

The timescale for giant planet formation : constraints from the rotational evolution of exoplanet host stars  

E-print Network

The timescale over which planets may form in the circumstellar disks of young stars is one of the main issues of current planetary formation models. We present here new constraints on planet formation timescales derived from the rotational evolution of exoplanet host stars.

Jerome Bouvier

2008-10-17

359

Millennial timescale carbon cycle and climate change in an efficient Earth system model.  

E-print Network

Millennial timescale carbon cycle and climate change in an efficient Earth system model. T. M and for traceability to earlier work. The model versions have climate sensitivity of 2.8-3.3 C and predict atmospheric temperature to anthro- pogenic CO2 emissions, will have a characteristic millennial timescale, set by the rate

Edwards, Neil

360

On the Chronometry and Metrology of Computer Network Timescales and their Application to the Network Time  

E-print Network

On the Chronometry and Metrology of Computer Network Timescales and their Application, and on calendar metrology, which is the determination of conventional civiltimeand date according to the modern, D.L. On the chronology and metrology of computer network timescales and their application

Mills, David L.

361

On the Chronometry and Metrology of Computer Network Timescales and their Application to the Network Time  

E-print Network

On the Chronometry and Metrology of Computer Network Timescales and their Application, and on calendar metrology, which is the determination of conventional civil time and date according to the modern. Reprinted from: Mills, D.L. On the chronology and metrology of computer network timescales and thei

Mills, David L.

362

Signatures of multiple time-scale behaviour in the power spectra of water  

E-print Network

Signatures of multiple time-scale behaviour in the power spectra of water Anirban Mudi are analysed for bulk SPC/E water for a range of temperatures along the 1.0 g/cm3 isochore. Fluctuations in the tagged particle potential energies give rise to 1=f a noise, indicative of multiple time-scale behaviour

Ramaswamy, Ram

363

Was Einstein Really a Pacifist? Einstein's Independent, Forward-Thinking, Flexible, and Self-Defined Pacifism  

NASA Astrophysics Data System (ADS)

Perhaps motivated by an admiration for Einstein and a desire to identify with him, combined with a majority world-view in opposition to pacifism, skeptics may often question whether Einstein was really a pacifist. They might point to the fact that his dramatic contributions to the field of physics at the beginning of the twentieth century made nuclear weapons possible, as well as his 1939 letter to President Franklin D. Roosevelt urging him to develop such weapons before the Nazis would, as examples of at least an inconsistent stance on pacifism across time on Einstein's part. However, as this paper will show, Einstein's pacifism began early in his life, was a deep-seated conviction that he expressed repeatedly across the years, and was an independent pacifism that flowed from his own responses to events around him and contained some original and impressively forward-thinking elements. Moreover, in calling himself a pacifist, as Einstein did, he defined pacifism in his own terms, not according to the standards of others, and this self-defined pacifism included the flexibility to designate the Nazis as a special case that had to be opposed through the use of military violence, in his view. As early as during his childhood, Einstein already disliked competitive games, because of the necessity of winners and losers, and disliked military discipline. In his late thirties, living in Germany during the First World War with a prestigious academic position in Berlin, yet retaining his identity as a Swiss citizen, Einstein joined a small group of four intellectuals who signed the pacifist ``Appeal to the Europeans'' in response to the militarist ``Manifesto to the Civilized World'' signed by 93 German intellectuals. In private, throughout that War, Einstein repeatedly expressed his disgust and sense of alienation at the ``war-enthusiasm'' sentiment of the majority. In the aftermath of the War, Einstein was involved in a German private commission to investigate German war crimes and the publication that it produced, and throughout the Weimar period of 1918 to 1933 Einstein continued to take public and private stances as a pacifist. As did many pacifists, Einstein also linked his advocacy for peace with a concern for social justice, which included opposition to antisemitism and advocacy for Zionism, and in 1929, after violent clashes between Jews and Arabs in Palestine, in which hundreds died on both sides, Einstein made some impressively forward-thinking statements about Jewish-Arab conciliation, and even published in an Arab newspaper his own proposal to set up a joint Jewish-Arab council for purposes of conflict resolution. But Einstein's pacifism was not forever obliterated by the Nazi era and the Holocaust, despite his well-known encouragement to Roosevelt to develop the bomb. In the United States, where he lived from 1933 on, in the first ten years after World War II, also the last decade of his life, Einstein inspired American pacifists with his strong stances against war and nuclear weapons.

Holmes, Virginia Iris

2005-03-01

364

On the absence of intrahelical DNA dynamics on the ?s to ms timescale.  

PubMed

DNA helices display a rich tapestry of motion on both short (<100?ns) and long (>1?ms) timescales. However, with the exception of mismatched or damaged DNA, experimental measures indicate that motions in the 1??s to 1?ms range are effectively absent, which is often attributed to difficulties in measuring motions in this time range. We hypothesized that these motions have not been measured because there is effectively no motion on this timescale, as this provides a means to distinguish faithful Watson-Crick base-paired DNA from damaged DNA. The absence of motion on this timescale would present a 'static' DNA sequence-specific structure that matches the encounter timescales of proteins, thereby facilitating recognition. Here we report long-timescale (~10-44??s) molecular dynamics simulations of a B-DNA duplex structure that addresses this hypothesis using both an 'Anton' machine and large ensembles of AMBER GPU simulations. PMID:25351257

Galindo-Murillo, Rodrigo; Roe, Daniel R; Cheatham, Thomas E

2014-01-01

365

Release timescales of solar energetic particles in the low corona  

NASA Astrophysics Data System (ADS)

Aims: We present a systematic study of the timing and duration of the release processes of near-relativistic (NR; >50 keV) electrons in the low corona. Methods: We analyze seven well-observed events using in situ measurements by both the ACE and Wind spacecraft and context electromagnetic observations in soft X-rays, radio, hard X-rays and white light. We make use of velocity dispersion analysis to estimate the release time of the first arriving electrons and compare with the results obtained by using a simulation-based approach, taking interplanetary transport effects into account to unfold the NR electron release time history from in situ measurements. Results: The NR electrons observed in interplanetary space appear to be released during either short (<30 min) or long (>2 h) periods. The observation of NR electron events showing beamed pitch-angle distributions (PADs) during several hours is the clearest observational signature of sustained release in the corona. On the other hand, the in situ observation of PADs isotropizing in less than a couple of hours is a clear signature of a prompt release of electrons in the low corona. Short release episodes appear to originate in solar flares, in coincidence with the timing of the observed type III radio bursts. Magnetic connectivity plays an important role. Only type III radio bursts reaching the local plasma line measured at 1 AU are found to be related with an associated release episode in the low corona. Other type III bursts may also have a release of NR electrons associated with them, but these electrons do not reach L1. Long release episodes appear associated with signatures of long acceleration processes in the low corona (long decay of the soft X-ray emission, type IV radio bursts, and time-extended microwave emission). Type II radio bursts are reported for most of the events and do not provide a clear discrimination between short and long release timescales.

Agueda, N.; Klein, K.-L.; Vilmer, N.; Rodríguez-Gasén, R.; Malandraki, O. E.; Papaioannou, A.; Subirà, M.; Sanahuja, B.; Valtonen, E.; Dröge, W.; Nindos, A.; Heber, B.; Braune, S.; Usoskin, I. G.; Heynderickx, D.; Talew, E.; Vainio, R.

2014-10-01

366

Rotating trapped Bose-Einstein condensates  

SciTech Connect

After reviewing the ideal Bose-Einstein gas in a box and in a harmonic trap, the effect of interactions on the formation of a Bose-Einstein condensate are discussed, along with the dynamics of small-amplitude perturbations (the Bogoliubov equations). When the condensate rotates with angular velocity {Omega}, one or several vortices nucleate, leading to many observable consequences. With more rapid rotation, the vortices form a dense triangular array, and the collective behavior of these vortices has additional experimental implications. For {Omega} near the radial trap frequency {omega}{sub perpendicular}, the lowest-Landau-level approximation becomes applicable, providing a simple picture of such rapidly rotating condensates. Eventually, as {Omega}{yields}{omega}{sub perpendicular}, the rotating dilute gas is expected to undergo a quantum phase transition from a superfluid to various highly correlated (nonsuperfluid) states analogous to those familiar from the fractional quantum Hall effect for electrons in a strong perpendicular magnetic field.

Fetter, Alexander L. [Geballe Laboratory for Advanced Materials and Departments of Physics and Applied Physics, Stanford University, Stanford, California 94305-4045 (United States)

2009-04-15

367

Astrophysical Bose-Einstein condensates and superradiance  

NASA Astrophysics Data System (ADS)

We investigate gravitational analogue models to describe slowly rotating objects (e.g., dark-matter halos, or boson stars) in terms of Bose-Einstein condensates, trapped in their own gravitational potentials. We begin with a modified Gross-Pitaevskii equation, and show that the resulting background equations of motion are stable, as long as the rotational component is treated as a small perturbation. The dynamics of the fluctuations of the velocity potential are effectively governed by the Klein-Gordon equation of an "Eulerian metric," where we derive the latter by the use of a relativistic Lagrangian extrapolation. Superradiant scattering on such objects is studied. We derive conditions for its occurrence and estimate its strength. Our investigations might give an observational handle to phenomenologically constrain Bose-Einstein condensates.

Kühnel, Florian; Rampf, Cornelius

2014-11-01

368

Two Versions of Gravity: Newton and Einstein  

NSDL National Science Digital Library

The goal of this lesson is for two groups of students to exchange information (e.g., through poster presentations, Podcasts, debates, or PowerPoint presentations) about how two different theories explain a natural phenomenon: Newton's Law of Gravitation and Einstein's General Theory of Relativity. The lesson will also illustrate how the scientific process allows a new, more complete theory to take the place of an older theory that does not produce accurate results for a new discovery. Students will need to have either studied both Newton's Law of Gravitation and Einstein's Theory of Relativity or be given the time and resources to look up this information. This lesson is part of the Cosmic Times teachers guide and is intended to be used in conjunction with the 1919 Cosmic Times Poster.

369

Axions: Bose Einstein Condensate or Classical Field?  

E-print Network

The axion is a motivated dark matter candidate, so it would be interesting to find features in Large Scale Structures specific to axion dark matter. Such features were proposed for a Bose Einstein condensate of axions, leading to confusion in the literature (to which I contributed) about whether axions condense due to their gravitational interactions. This note argues that the Bose Einstein condensation of axions is a red herring: the axion dark matter produced by the misalignment mechanism is already a classical field, which has the distinctive features attributed to the axion condensate (BE condensates are described as classical fields). The rate at which gravity could condense the cold axion particles produced from strings is estimated to be negligeable.

Sacha Davidson

2014-05-06

370

Bose-Einstein Condensation of Pions  

E-print Network

Particle number fluctuations are studied in the ideal pion gas approaching Bose-Einstein condensation. Two different cases are considered: Bose condensation of pions at large charge densities $\\rho_Q$ and Bose condensation at large total densities of pions $\\rho_{\\pi}$. Calculations are done in grand canonical, canonical and microcanonical ensembles. At high collision energy, in the samples of events with a fixed number of all pions, $N_{\\pi}$, one may observe a prominent signal. When $N_{\\pi}$ increases the scaled variances for particle number fluctuations of both neutral and charged pions increase dramatically in the vicinity of the Bose-Einstein condensation line. As an example, the estimates are presented for $p+p$ collisions at the beam energy of 70 GeV.

Viktor Begun; Mark Gorenstein

2007-09-10

371

A modification of Einstein-Schrödinger theory that contains Einstein-Maxwell-Yang-Mills theory  

NASA Astrophysics Data System (ADS)

The Lambda-renormalized Einstein-Schrödinger theory is a modification of the original Einstein-Schrödinger theory in which a cosmological constant term is added to the Lagrangian, and it has been shown to closely approximate Einstein- Maxwell theory. Here we generalize this theory to non-Abelian fields by letting the fields be composed of d × d Hermitian matrices. The resulting theory incorporates the U(1) and SU( d) gauge terms of Einstein-Maxwell-Yang-Mills theory, and is invariant under U(1) and SU( d) gauge transformations. The special case where symmetric fields are multiples of the identity matrix closely approximates Einstein-Maxwell-Yang-Mills theory in that the extra terms in the field equations are < 10-13 of the usual terms for worst-case fields accessible to measurement. The theory contains a symmetric metric and Hermitian vector potential, and is easily coupled to the additional fields of Weinberg-Salam theory or flipped SU(5) GUT theory. We also consider the case where symmetric fields have small traceless parts, and show how this suggests a possible dark matter candidate.

Shifflett, James A.

2009-08-01

372

Results from an extensive Einstein stellar survey  

Microsoft Academic Search

The preliminary results of the Einstein Observatory stellar X-ray survey are presented. To date, 143 soft X-ray sources have been identified with stellar counterparts, leaving no doubt that stars in general constitute a pervasive class of low-luminosity galactic X-ray sources. Stars along the entire main sequence, of all luminosity classes, pre-main sequence stars as well as very evolved stars have

G. S. Vaiana; J. P. Cassinelli; G. Fabbiano; R. Giacconi; L. Golub; P. Gorenstein; B. M. Haisch; F. R. Harnden Jr.; H. M. Johnson; J. L. Linsky; C. W. Maxson; R. Mewe; R. Rosner; F. Seward; K. Topka; C. Zwaan

1981-01-01

373

Embeddings for solutions of Einstein equations  

E-print Network

We study isometric embeddings of some solutions of the Einstein equations with suffciently high symmetries into a flat ambient space. We briefly describe a method for constructing surfaces with a given symmetry. We discuss all minimal embeddings of the Schwarzschild metric obtained using this method and show how the method can be used to construct all minimal embeddings for the Friedmann models. We classify all the embeddings in terms of realizations of symmetries of the corresponding solutions.

S. A. Paston; A. A. Sheykin

2013-06-20

374

Hysteresis effects in Bose-Einstein condensates  

E-print Network

Here, we consider damped two-components Bose-Einstein condensates with many-body interactions. We show that, when the external trapping potential has a double-well shape and when the nonlinear coupling factors are modulated in time, hysteresis effects may appear under some circumstances. Such hysteresis phenomena are a result of the joint contribution between the appearance of saddle node bifurcations and damping effect.

Andrea Sacchetti

2010-06-16

375

Nonrelativistic limit of the Einstein equation  

Microsoft Academic Search

In particular cases of stationary and stationary axially symmetric space-time\\u000apassage to non-relativistic limit of Einstein equation is completed. For this\\u000aend the notions of absolute space and absolute time are introduced due to\\u000astationarity of the space-time under consideration. In this construction\\u000aabsolute time is defined as a function $t$ on the space-time such that $\\\\prt_t$\\u000ais exactly the

Z. Ya. Turakulov

2007-01-01

376

Nonrelativistic limit of the Einstein equation  

Microsoft Academic Search

In particular cases of stationary and stationary axially symmetric space-time passage to non-relativistic limit of Einstein equation is completed. For this end the notions of absolute space and absolute time are introduced due to stationarity of the space-time under consideration. In this construction absolute time is defined as a function $t$ on the space-time such that $\\\\prt_t$ is exactly the

Z. Ya. Turakulov

2007-01-01

377

Passing the Einstein-Rosen bridge  

NASA Astrophysics Data System (ADS)

A test particle moving along geodesic line in a spacetime has three physical propagating degrees of freedom and one unphysical gauge degree. We relax the requirement of geodesic completeness of a spacetime. Instead, we require test particles trajectories to be smooth and complete only for physical degrees of freedom. Test particles trajectories for Einstein-Rosen bridge are proved to be smooth and complete in the physical sector, and particles can freely penetrate the bridge in both directions.

Katanaev, M. O.

2014-05-01

378

General Relativity; An Einstein Centenary Survey  

NSDL National Science Digital Library

Written in honor of Albert Einstein's 100th birthday, this text was created by 21 experts in the theory of relativity to present the current state of research in the subject. Written at a very high level, especially in the mathematics, the survey tracks the history, development, and consequences of the theory of general relativity. This book is out of print, but is available from used-book sellers.

2009-02-19

379

Finding solutions to the Einstein equations  

NASA Astrophysics Data System (ADS)

This dissertation is a description of a variety of methods of solving the Einstein equations describing the gravitational interaction in different mathematical and astrophysical settings. We begin by discussing a numerical study of the Einstein-Yang-Mills-Higgs system in spherical symmetry. The equations are presented along with boundary and initial conditions. An explanation of the numerical scheme is then given. This is followed by a discussion of the solutions obtained together with an interpretation in the context of gravitational collapse and critical phenomena at the threshold of black hole formation. Following this, we generalize the same system to axisymmetry. The full, gravitational equations are presented along with a short discussion of the problems we encountered in trying to solve these. As a first step we consider evolving the matter fields in flat space. The simplified equations are given and the numerical scheme implemented to solve them discussed. We then consider some analytic techniques to understanding the Einstein equations and the gravitating systems they should describe. One such is to change the spacetime dimension. This we do in considering magnetic solutions to the (2 + 1) Einstein-Maxwell-Dilaton system with nonzero cosmological constant. The solutions are investigated to determine whether these correspond to “soliton”-like solutions or black holes. As another example of this general approach, we introduce an extra timelike coordinate into the spherically symmetric vacuum system, and attempt to find a solution comparing the result to the more well known Schwarzschild solution. Finally, we give a short description of some preliminary work which will combine some of these numerical and analytical techniques. This approach simply takes the matter fields as weak and propagates them on a fixed spacetime background. In our particular case, we intend to study the evolution of Maxwell fields in the Schwarzschild geometry. We provide motivation for this as well as present the equations describing the system.

Millward, Robert Steven

2004-07-01

380

Faraday Patterns in Bose-Einstein Condensates  

Microsoft Academic Search

Parametric excitation of Bose-Einstein condensates (BECs) has been shown numerically to create similar patterns as those produced when a liquid is vibrated up and down sinusoidally. In this project, we reproduce the results of single-frequency forcing in BECs and conduct a prelimi- nary investigation of double-frequency forcing. We analyze the stability of the spatially homogeneous, temporally periodic solution of the

Tatjana S. Wiese

381

Gravity Probe B: Testing Einstein's Universe  

NSDL National Science Digital Library

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. The experiment will use changes in the direction of spin of four gyroscopes contained in an Earth satellite to measure how space and time are warped by the presence of the Earth, and, more profoundly, how the Earth's rotation drags spacetime around with it.

Everitt, C. W.

2003-10-10

382

Timescales in creep and yielding of attractive gels.  

PubMed

The stress-induced yielding scenario of colloidal gels is investigated under rough boundary conditions by means of rheometry coupled with local velocity measurements. Under an applied shear stress ?, the fluidization of gels made of attractive carbon black particles dispersed in a mineral oil is shown to involve a previously unreported shear rate response ? dot above(t) characterized by two well-defined and separated timescales ?c and ?f. First ? dot above decreases as a weak power law strongly reminiscent of the primary creep observed in numerous crystalline and amorphous solids, coined the "Andrade creep". We show that the bulk deformation remains homogeneous at the micron scale, which demonstrates that whether plastic events take place or whether any shear transformation zone exists, such phenomena occur at a smaller scale. As a key result of this paper, the duration ?c of this creep regime decreases as a power law of the viscous stress, defined as the difference between the applied stress and the yield stress ?c, i.e. ?c ? (? - ?c)(-?), with ? = 2-3 depending on the gel concentration. The end of this first regime is marked by a jump of the shear rate by several orders of magnitude, while the gel slowly slides as a solid block experiencing strong wall slip at both walls, despite rough boundary conditions. Finally, a second sudden increase of the shear rate is concomitant with the full fluidization of the material which ends up being homogeneously sheared. The corresponding fluidization time ?f robustly follows an exponential decay with the applied shear stress, i.e. ?f = ?0?exp(-?/?0), as already reported for smooth boundary conditions. Varying the gel concentration C in a systematic fashion shows that the parameter ?0 and the yield stress ?c exhibit similar power-law dependences with C. Finally, we highlight a few features that are common to attractive colloidal gels and to solid materials by discussing our results in the framework of theoretical approaches of solid rupture (kinetic, fiber bundle, and transient network models). PMID:24651869

Grenard, Vincent; Divoux, Thibaut; Taberlet, Nicolas; Manneville, Sébastien

2014-03-14

383

ASYMPTOTIC SELF-SIMILAR SOLUTIONS WITH A CHARACTERISTIC TIMESCALE  

SciTech Connect

For a wide variety of initial and boundary conditions, adiabatic one-dimensional flows of an ideal gas approach self-similar behavior when the characteristic length scale over which the flow takes place, R, diverges or tends to zero. It is commonly assumed that self-similarity is approached since in the R {yields} {infinity}(0) limit the flow becomes independent of any characteristic length or timescales. In this case, the flow fields f(r, t) must be of the form f(r,t)=t{sup {alpha}}{sub f}F(r/R) with R {proportional_to} ({+-}t){sup {alpha}}. We show that requiring the asymptotic flow to be independent only of characteristic length scales implies a more general form of self-similar solutions, f(r,t)=R{sup {delta}}{sub f}F(r/R) with R-dot {proportional_to}R{sup {delta}}, which includes the exponential ({delta} = 1) solutions, R {proportional_to} e {sup t/{tau}}. We demonstrate that the latter, less restrictive, requirement is the physically relevant one by showing that the asymptotic behavior of accelerating blast waves, driven by the release of energy at the center of a cold gas sphere of initial density {rho} {proportional_to} r {sup -{omega}}, changes its character at large {omega}: the flow is described by 0 {<=} {delta} < 1, R {proportional_to} t {sup 1/(1-{delta})}, solutions for {omega} < {omega}{sub c}, by {delta}>1 solutions with R {proportional_to} (-t){sup 1/({delta}-1)} diverging at finite time (t = 0) for {omega}>{omega}{sub c}, and by exponential solutions for {omega} = {omega}{sub c} ({omega}{sub c} depends on the adiabatic index of the gas, {omega}{sub c} {approx} 8 for 4/3 < {gamma} < 5/3). The properties of the new solutions obtained here for {omega} {>=} {omega}{sub c} are analyzed, and self-similar solutions describing the t>0 behavior for {omega}>{omega}{sub c} are also derived.

Waxman, Eli [Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 76100 (Israel); Shvarts, Dov [Department of Physics, Nuclear Research Center Negev, P.O. Box 9001, Beer-Sheva 84015 (Israel)

2010-10-01

384

Characteristic Timescales of Shoreface Response to Sea-Level Rise  

NASA Astrophysics Data System (ADS)

On open ocean, wave-dominated, sandy coasts, the response of the shore to sea-level rise is dominated not by inundation, but rather by the dynamic response of sediment transport processes to perturbations of the sea level. In a regime of sea level change, the predominant response of the wave-dominated shoreface depends upon the time-dependent response of the shoreface itself to changes in sea level as well as the potential changes to the shoreline. On a barrier coast, persistent, long-term changes to the shoreline are caused by storm overwash, which transports marine sediment landward, moving the shoreline boundary. Raised sea levels increase the impact and frequency of this overwash as relative barrier elevation is reduced. Overall, sediment transport processes on the shoreface remain poorly understood, complicating predictions of equilibrium shoreface shapes and even net sediment transport directions. However, presuming an equilibrium geometry, energetics-based, time-averaged relationships for cross-shore sediment transport provide a framework to understand the characteristic rates and types of shoreface response to perturbations to either the sea level or the shoreline boundary. In the case of a sea-level rise, we find that the dominant perturbation for a barrier system is not the sea-level rise itself, but rather the movement of the shoreline by overwash. The characteristic response time of the shoreface itself increases significantly at depth, suggesting that the lower shoreface response to a sea level change can be significantly delayed. We estimate the importance of extreme events on shoreface evolution by analyzing decade-long data series of wave characteristics along different open ocean coasts with barriers (Florida Gulf Coast, North Carolina, Marthas Vineyard). Analogous to the effect of floods in fluvial systems, although storm events can move significant sediment, the infrequency of the larger events limits their effect on the shoreface-the morphologically significant event for shoreface evolution has a return interval of less than two years. However, numerical simulations of tens of thousands of synthetic storm strikes at the same locations suggest that the return interval of storm events expected to cause significant overwash is longer, on the order of at least 50 years. To study the interactions between the characteristic timescales of shoreface evolution and barrier overwash, we apply a numerical model of barrier profile evolution that couples shoreface evolution with barrier overwash. This integrated model provides a tool to understand the response of barrier systems to changes in sea level over the late Holocene to the modern. The model also investigates the potential behavior of barrier systems as they (and their human occupants) respond to predicted increased rates of sea-level rise over the coming centuries.

Ashton, A. D.; Ortiz, A.; Lane, P.; Donnelly, J. P.

2011-12-01

385

Einstein's vierbein field theory of curved space  

E-print Network

General Relativity theory is reviewed following the vierbein field theory approach proposed in 1928 by Einstein. It is based on the vierbein field taken as the "square root" of the metric tensor field. Einstein's vierbein theory is a gauge field theory for gravity; the vierbein field playing the role of a gauge field but not exactly like the vector potential field does in Yang-Mills theory--the correction to the derivative (the covariant derivative) is not proportional to the vierbein field as it would be if gravity were strictly a Yang-Mills theory. Einstein discovered the spin connection in terms of the vierbein fields to take the place of the conventional affine connection. To date, one of the most important applications of the vierbein representation is for the derivation of the correction to a 4-spinor quantum field transported in curved space, yielding the correct form of the covariant derivative. Thus, the vierbein field theory is the most natural way to represent a relativistic quantum field theory in...

Yepez, Jeffrey

2011-01-01

386

Einstein's Universe - Gravity at Work and Play  

NASA Astrophysics Data System (ADS)

On Albert Einstein's seventy-sixth and final birthday, a friend gave him a simple toy made from a broomstick, a brass ball attached to a length of string, and a weak spring. Einstein was delighted: the toy worked on a principle he had conceived fifty years earlier when he was working on his revolutionary theory of gravitya principle whose implications are still confounding physicists today.Starting with this winning anecdote, Anthony Zee begins his animated discussion of phenomena ranging from the emergence of galaxies to the curvature of space-time, evidence for the existence of gravity waves, and the shape of the universe in the first nanoseconds of creation and today. Making complex ideas accessible without oversimplifying, Zee leads the reader through the implications of Einstein's theory and its influence on modern physics. His playful and lucid style conveys the excitement of some of the latest developments in physics, and his new Afterword brings things even further up-to-date.

Zee, A.

2001-07-01

387

An astrophysical peek into Einstein's static universe  

E-print Network

For the sake of physical insight, we derive here the metric for Einstein's static universe (ESU) directly from Einstein equation, i.e., by considering both Einstein tensor $G_{ik}$ and energy momentum tensor $T_{ik}$. We find that in order that fluid pressure and acceleration are {\\em uniform} and finite despite the presence of a coordinate singularity, the effective density $\\rho_e = \\rho + \\Lambda/8 \\pi =0$, where $\\Lambda$ is the cosmological constant. Under weak energy condition, this would imply $\\rho = \\Lambda =0$ for ESU! It is pointed out that {\\em mean} $\\rho$ could be zero in some fractal cosmological models. One may also have a mean $\\rho =0$ for an infinite universe where observed patches of matter distribution are separated by voids of infinite extent. However, such theoretical considerations may not be relevant for a {\\em non static} universe. Further, if the supposed accelerated expansion of the observed luminous part of the universe is genuine, it could be because of some complex time dependen...

Mitra, Abhas

2008-01-01

388

Nanosecond Motions in Proteins Impose Bounds on the Timescale Distributions of Local Dynamics  

PubMed Central

Abstract We elucidate the physics of protein dynamical transition via 10–100-ns molecular dynamics simulations at temperatures spanning 160–300 K. By tracking the energy fluctuations, we show that the protein dynamical transition is marked by a crossover from nonstationary to stationary processes that underlie the dynamics of protein motions. A two-timescale function captures the nonexponential character of backbone structural relaxations. One timescale is attributed to the collective segmental motions and the other to local relaxations. The former is well defined by a single-exponential, nanosecond decay, operative at all temperatures. The latter is described by a set of processes that display a distribution of timescales. Although their average remains on the picosecond timescale, the distribution is markedly contracted at the onset of the transition. It is shown that the collective motions impose bounds on timescales spanned by local dynamical processes. The nonstationary character below the transition implicates the presence of a collection of substates whose interactions are restricted. At these temperatures, a wide distribution of local-motion timescales, extending beyond that of nanoseconds, is observed. At physiological temperatures, local motions are confined to timescales faster than nanoseconds. This relatively narrow window makes possible the appearance of multiple channels for the backbone dynamics to operate. PMID:19804740

Okan, Osman Burak; Atilgan, Ali Rana; Atilgan, Canan

2009-01-01

389

Newton's law on an Einstein "Gauss-Bonnet" brane  

E-print Network

It is known that Newton's law of gravity holds asymptotically on a flat "brane" embedded in an anti-de Sitter "bulk" ; this was shown not only when gravity in the bulk is described by Einstein's theory but also in Einstein "Lanczos Lovelock Gauss-Bonnet"'s theory. We give here the expressions for the corrections to Newton's potential in both theories, in analytic form and valid for all distances. We find that in Einstein's theory the transition from the 1/r behaviour at small r to the 1/r^2 one at large r is quite slow. In the Einstein Gauss-Bonnet case on the other hand, we find that the correction to Newton's potential can be small for all r. Hence, Einstein Gauss-Bonnet equations in the bulk (rather than simply Einstein's) induce on the brane a better approximation to Newton's law.

Nathalie Deruelle; Misao Sasaki

2003-06-09

390

Extended Horava gravity and Einstein-aether theory  

SciTech Connect

Einstein-aether theory is general relativity coupled to a dynamical, unit timelike vector. If this vector is restricted in the action to be hypersurface orthogonal, the theory is identical to the IR limit of the extension of Horava gravity proposed by Blas, Pujolas and Sibiryakov. Hypersurface orthogonal solutions of Einstein-aether theory are solutions to the IR limit of this theory, hence numerous results already obtained for Einstein-aether theory carry over.

Jacobson, Ted [Center for Fundamental Physics, University of Maryland, College Park, Maryland 20742-4111 (United States)

2010-05-15

391

Einstein centennial review article \\/ Article de synthèse commémoratif du centenaire de l'année miraculeuse d'Einstein A second century of Einstein? Bose-Einstein condensation and quantum information1  

Microsoft Academic Search

A century ago Albert Einstein transformed classical physics with his seminal papers on Brownian motion, the Photoelectric effect, and, of course, special and later general relativity. Lesser well-known are his contributions to Bose-Einstein Condensation and the Einstein-Podolsky-Rosen paradox, the latter being a criticism of Quantum Mechanics. These later works were regarded even by physicists for decades as mere Gedanken or

William Arie van Wijngaarden

392

On the projective algebra of Einstein Matsumoto metrics  

E-print Network

The projective algebra p(M;F) (i.e the collection of all projective vector fields)of a Finsler space (M;F) is a finite-dimensional Lie algebra with respect to the usual Lie bracket. The projective algebra of Einstein metrics has been perpetually studied from physical and geometrical approaches. Here, the projective algebra of Einstein Matsumoto space of dimension n \\geq 3 is characterized. Moreover, Einstein Matsumoto metrics with maximum projective symmetry are studied and characterized.

Rafie-Rad, M

2011-01-01

393

On Conformal Powers of the Dirac Operator on Einstein Manifolds  

E-print Network

We determine the structure of conformal powers of the Dirac operator on Einstein {\\it Spin}-manifolds in terms of the product formula for shifted Dirac operators. The result is based on the techniques of higher variations for the Dirac operator on Einstein manifolds and spectral analysis of the Dirac operator on the associated Poincar\\'e-Einstein metric, and relies on combinatorial recurrence identities related to the dual Hahn polynomials.

Matthias Fischmann; Christian Krattenthaler; Petr Somberg

2014-05-28

394

Einstein's medical friends and their influence on his life.  

PubMed

Albert Einstein had at least six medical friends who influenced his thoughts. In each period (Munich, Switzerland, Berlin and Princeton) of his life, one could identify the medically qualified individuals with whom Einstein was in close contact. These include Max Talmey, Heinrich Zangger, George Nicolai, Hans Mühsam, Janos Plesch and Gustav Bucky. They probably enriched Einstein's life and thoughts significantly by being mentors, confidants, intellectual sparring partners and research collaborators to him. With Mühsam, Einstein published a paper in a German medical journal. In collaboration with Bucky, he also received a US patent for a light-intensity self-adjusting camera in 1936. PMID:8676763

Kantha, S S

1996-03-01

395

``Your Most Distinguished Contributor'': Einstein and the Physical Review  

NASA Astrophysics Data System (ADS)

Einstein began to publish in the Physical Review after he began working with his first American research assistant, Nathan Rosen. They submitted three landmark papers together to the journal. These papers and their reception are discussed, along with the remarkable story of Einstein's umbrage at the referee report he received in response to his third submission. Although the referee was vindicated and Einstein eventually had to reverse his position, he never submitted a research paper to the Physical Review again. The identity of the referee, as learned from the Review's own records, will be revealed and Einstein's subsequent relationship with the journal will be discussed.

Kennefick, Daniel

2013-03-01

396

ALBERT EINSTEIN COLLEGE OF MEDICINE of YESHIVA UNIVERSITY  

E-print Network

ALBERT EINSTEIN COLLEGE OF MEDICINE of YESHIVA UNIVERSITY JACK and PEARL RESNICK CAMPUS DEPARTMENT of ENVIRONMENTAL HEALTH & SAFETY Safety is Everyone's Responsibility INDOOR AIR QUALITY QUESTIONNAIRE 1. Name

Emmons, Scott

397

Variability of gamma-ray emission from blazars on the black hole timescales  

E-print Network

We investigate the variability properties of blazars in the GeV band using the data of the Fermi/LAT telescope. We find that blazars exhibit variability on the scales down to the minimal timescale resolvable by Fermi, which is a function of the peak photon count rate in the LAT. This implies that the real minimal variability timescales for the majority of blazars are typically shorter than those resolvable by the LAT. We find that for several blazars these minimal variability timescales reach those associated to the blazar central engine, the supermassive black hole. At the same time, none of the blazars exhibits variability on the timescale shorter than the black hole horizon light crossing time and/or the period of rotation around the last stable circular orbit. Based on this fact, we argue that the timing properties of the gamma-ray signal could be determined by the processes in the direct vicinity of the supermassive black hole.

Vovk, Ievgen

2013-01-01

398

Variability of Gamma-Ray Emission from Blazars on Black Hole Timescales  

NASA Astrophysics Data System (ADS)

We investigate the variability properties of blazars in the GeV band using data from the Fermi/Large Area Telescope (LAT) telescope. We find that blazars exhibit variability down to the minimum timescale resolvable by Fermi; this variability is a function of the peak photon count rate in the LAT. This implies that the real minimum variability timescales for the majority of blazars are typically shorter than those resolvable by the LAT. We find that for several blazars these minimum variability timescales reach those associated with the blazar central engine, the supermassive black hole. At the same time, none of the blazars exhibits variability on a timescale shorter than the black hole horizon light-crossing time and/or the period of rotation around the last stable circular orbit. Based on this fact, we argue that the timing properties of the ?-ray signal could be determined by the processes in the direct vicinity of the supermassive black hole.

Vovk, Ie.; Neronov, A.

2013-04-01

399

VARIABILITY OF GAMMA-RAY EMISSION FROM BLAZARS ON BLACK HOLE TIMESCALES  

SciTech Connect

We investigate the variability properties of blazars in the GeV band using data from the Fermi/Large Area Telescope (LAT) telescope. We find that blazars exhibit variability down to the minimum timescale resolvable by Fermi; this variability is a function of the peak photon count rate in the LAT. This implies that the real minimum variability timescales for the majority of blazars are typically shorter than those resolvable by the LAT. We find that for several blazars these minimum variability timescales reach those associated with the blazar central engine, the supermassive black hole. At the same time, none of the blazars exhibits variability on a timescale shorter than the black hole horizon light-crossing time and/or the period of rotation around the last stable circular orbit. Based on this fact, we argue that the timing properties of the {gamma}-ray signal could be determined by the processes in the direct vicinity of the supermassive black hole.

Vovk, Ie.; Neronov, A. [ISDC Data Centre for Astrophysics, Ch. d'Ecogia 16, CH-1290, Versoix (Switzerland)

2013-04-20

400

ATHENA SWAN 3 YEAR ACTION PLAN THE ROSLIN INSTITUTE Objective Action Timescale Responsibility Success Measure  

E-print Network

ATHENA SWAN 3 YEAR ACTION PLAN ­ THE ROSLIN INSTITUTE Objective Action Timescale Responsibility by relevant committees. #12;ATHENA SWAN 3 YEAR ACTION PLAN ­ THE ROSLIN INSTITUTE 1.5 Increase the number

Hall, Christopher

401

Determining timescales of natural carbonation of peridotite in the Samail Ophiolite, Sultanate of Oman  

E-print Network

Determining timescales of the formation and preservation of carbonate alteration products in mantle peridotite is important in order to better understand the role of this potentially important sink in the global carbon ...

Mervine, Evelyn Martinique

2012-01-01

402

Revisiting the Einstein-Bohr Dialogue Einstein and Bohr No names loom larger in the history of twentieth-century physics, and  

E-print Network

in the history of twentieth-century physics, and rightly so, Albert Einstein and Niels Bohr being the figuresRevisiting the Einstein-Bohr Dialogue Don Howard Einstein and Bohr ­ No names loom larger identified complementarity as the chief novelty in the quantum description of nature, Einstein for having

Howard, Don

403

GRAVITATION & DARK ENERGY Part One (of 3) : Einstein's Theory of General Relativity  

E-print Network

of the human race. Let's see how easy it was for Albert Einstein to discoverGRAVITATION & DARK ENERGY 1 Part One (of 3) : Einstein's Theory General Relativity. Einstein's truly brilliant idea was that the presence

404

Water Peak Suppression: Time-Frequency vs TimeScale Approach  

Microsoft Academic Search

Wavelets are the most popular time-scale analysis tool. A well-known application of wavelets in nuclear magnetic resonance spectroscopy is water peak extraction\\/suppression. However, spectroscopists are more familiar with frequency than scale. So, from a spectroscopist point of view, a time-scale analysis tool (i.e., wavelets) is not natural and a time-frequency approach would be much more satisfactory. We explain a time-frequency

Jean-Pierre Antoine; Alain Coron; Jean-Marie Dereppe

2000-01-01

405

On the Nature of the Prototype Luminous Blue Variable AG Carinae. II. Witnessing a Massive Star Evolving Close to the Eddington and Bistability Limits  

NASA Astrophysics Data System (ADS)

We show that the significantly different effective temperatures (T eff) achieved by the luminous blue variable AG Carinae during the consecutive visual minima of 1985-1990 (T eff ~= 22,800 K) and 2000-2001 (T eff ~= 17,000 K) place the star on different sides of the bistability limit, which occurs in line-driven stellar winds around T eff ~ 21,000 K. Decisive evidence is provided by huge changes in the optical depth of the Lyman continuum in the inner wind as T eff changes during the S Dor cycle. These changes cause different Fe ionization structures in the inner wind. The bistability mechanism is also related to the different wind parameters during visual minima: the wind terminal velocity was 2-3 times higher and the mass-loss rate roughly two times smaller in 1985-1990 than in 2000-2003. We obtain a projected rotational velocity of 220 ± 50 km s-1 during 1985-1990 which, combined with the high luminosity (L sstarf = 1.5 × 106 L sun), puts AG Car extremely close to the Eddington limit modified by rotation (?? limit): for an inclination angle of 90°, ?? >~ 1.0 for M sun <~ 60. Based on evolutionary models and mass budget, we obtain an initial mass of ~100 M sun and a current mass of ~60-70 M sun for AG Car. Therefore, AG Car is close to, if not at, the ?? limit during visual minimum. Assuming M = 70 M sun, we find that ?? decreases from 0.93 to 0.72 as AG Car expands toward visual maximum, suggesting that the star is not above the Eddington limit during maximum phases.

Groh, J. H.; Hillier, D. J.; Damineli, A.

2011-07-01

406

A fitting formula for the merger timescale of galaxies in hierarchical clustering  

E-print Network

We study galaxy mergers using a high-resolution cosmological hydro/N-body simulation with star formation, and compare the measured merger timescales with theoretical predictions based on the Chandrasekhar formula. In contrast to Navarro et al., our numerical results indicate, that the commonly used equation for the merger timescale given by Lacey and Cole, systematically underestimates the merger timescales for minor mergers and overestimates those for major mergers. This behavior is partly explained by the poor performance of their expression for the Coulomb logarithm, \\ln (m_pri/m_sat). The two alternative forms \\ln (1+m_pri/m_sat) and 1/2\\ln [1+(m_pri/m_sat)^2] for the Coulomb logarithm can account for the mass dependence of merger timescale successfully, but both of them underestimate the merger time scale by a factor 2. Since \\ln (1+m_pri/m_sat) represents the mass dependence slightly better we adopt this expression for the Coulomb logarithm. Furthermore, we find that the dependence of the merger timescale on the circularity parameter \\epsilon is much weaker than the widely adopted power-law \\epsilon^{0.78}, whereas 0.94*{\\epsilon}^{0.60}+0.60 provides a good match to the data. Based on these findings, we present an accurate and convenient fitting formula for the merger timescale of galaxies in cold dark matter models.

C. Y. Jiang; Y. P. Jing; A. Faltenbacher; W. P. Lin; Cheng Li

2007-07-18

407

Time-scale invariance as an emergent property in a perceptron with realistic, noisy neurons  

PubMed Central

In most species, interval timing is time-scale invariant: errors in time estimation scale up linearly with the estimated duration. In mammals, time-scale invariance is ubiquitous over behavioral, lesion, and pharmacological manipulations. For example, dopaminergic drugs induce an immediate, whereas cholinergic drugs induce a gradual, scalar change in timing. Behavioral theories posit that time-scale invariance derives from particular computations, rules, or coding schemes. In contrast, we discuss a simple neural circuit, the perceptron, whose output neurons fire in a clockwise fashion (interval timing) based on the pattern of coincidental activation of its input neurons. We show numerically that time-scale invariance emerges spontaneously in a perceptron with realistic neurons, in the presence of noise. Under the assumption that dopaminergic drugs modulate the firing of input neurons, and that cholinergic drugs modulate the memory representation of the criterion time, we show that a perceptron with realistic neurons reproduces the pharmacological clock and memory patterns, and their time-scale invariance, in the presence of noise. These results suggest that rather than being a signature of higher-order cognitive processes or specific computations related to timing, time-scale invariance may spontaneously emerge in a massively-connected brain from the intrinsic noise of neurons and circuits, thus providing the simplest explanation for the ubiquity of scale invariance of interval timing. PMID:23518297

Buhusi, Catalin V.; Oprisan, Sorinel A.

2013-01-01

408

Six-Degree-of-Freedom Trajectory Optimization Utilizing a Two-Timescale Collocation Architecture  

NASA Technical Reports Server (NTRS)

Six-degree-of-freedom (6DOF) trajectory optimization of a reentry vehicle is solved using a two-timescale collocation methodology. This class of 6DOF trajectory problems are characterized by two distinct timescales in their governing equations, where a subset of the states have high-frequency dynamics (the rotational equations of motion) while the remaining states (the translational equations of motion) vary comparatively slowly. With conventional collocation methods, the 6DOF problem size becomes extraordinarily large and difficult to solve. Utilizing the two-timescale collocation architecture, the problem size is reduced significantly. The converged solution shows a realistic landing profile and captures the appropriate high-frequency rotational dynamics. A large reduction in the overall problem size (by 55%) is attained with the two-timescale architecture as compared to the conventional single-timescale collocation method. Consequently, optimum 6DOF trajectory problems can now be solved efficiently using collocation, which was not previously possible for a system with two distinct timescales in the governing states.

Desai, Prasun N.; Conway, Bruce A.

2005-01-01

409

COMPARISON OF KEPLER PHOTOMETRIC VARIABILITY WITH THE SUN ON DIFFERENT TIMESCALES  

SciTech Connect

We utilize Kepler data to study the precision differential photometric variability of solar-type and cooler stars at different timescales, ranging from half an hour to three months. We define a diagnostic that characterizes the median differential intensity change between data bins of a given timescale. We apply the same diagnostics to Solar and Heliospheric Observatory data that has been rendered comparable to Kepler. The Sun exhibits similar photometric variability on all timescales as comparable solar-type stars in the Kepler field. The previously defined photometric ''range'' serves as our activity proxy (driven by starspot coverage). We revisit the fraction of comparable stars in the Kepler field that are more active than the Sun. The exact active fraction depends on what is meant by ''more active than the Sun'' and on the magnitude limit of the sample of stars considered. This active fraction is between a quarter and a third (depending on the timescale). We argue that a reliable result requires timescales of half a day or longer and stars brighter than M{sub Kep} of 14, otherwise non-stellar noise distorts it. We also analyze main sequence stars grouped by temperature from 6500 to 3500 K. As one moves to cooler stars, the active fraction of stars becomes steadily larger (greater than 90% for early M dwarfs). The Sun is a good photometric model at all timescales for those cooler stars that have long-term variability within the span of solar variability.

Basri, Gibor [Astronomy Department, University of California, Hearst Field Annex, Berkeley, CA 94720 (United States); Walkowicz, Lucianne M. [Department of Astrophysical Sciences, Princeton University, Peyton Hall, 4 Ivy Lane, Princeton NJ 08534 (United States); Reiners, Ansgar [Georg-August-University Goettingen, Institute for Astrophysics, Friedrich-Hund-Platz 1, DE D-37077, Goettingen (Germany)

2013-05-20

410

Curvature fluctuations on asymptotically de Sitter spacetimes via the semiclassical Einstein?s equations  

NASA Astrophysics Data System (ADS)

It has been proposed recently to consider in the framework of cosmology an extension of the semiclassical Einstein?s equations in which the Einstein tensor is considered as a random function. This paradigm yields a hierarchy of equations between the n-point functions of the quantum, normal ordered, stress-energy tensor and those associated to the stochastic Einstein tensor. Assuming that the matter content is a conformally coupled massive scalar field on de Sitter spacetime, this framework has been applied to compute the power spectrum of the quantum fluctuations and to show that it is almost scale-invariant. We test the robustness and the range of applicability of this proposal by applying it to a less idealized, but physically motivated, scenario, namely we consider Friedmann–Robertson–Walker spacetimes which behave only asymptotically in the past as a de Sitter spacetime. We show in particular that, under this new assumption and independently from any renormalization freedom, the power spectrum associated to scalar perturbations of the metric behaves consistently with an almost scale-invariant power spectrum.

Dappiaggi, Claudio; Melati, Alberto

2014-12-01

411

Albert Einstein - Chief Engineer of the Universe: 100 Authors for Einstein Essays  

Microsoft Academic Search

In 1905, Albert Einstein published five scientific articles that fundamentally changed the world-view of physics: The Special Theory of Reativity revolutionized our concept of space and time, E=mc² became the best-known equation in physics. On the occasion of the 100th aniversary of his \\

Jürgen Renn

2005-01-01

412

An astrophysical peek into Einstein's static universe  

E-print Network

We derive here the metric for Einstein's static universe (ESU) directly from Einstein equation, i.e., by considering both $G_{ik}$ and $T_{ik}$. We find that in order that the fluid pressure and acceleration are {\\em uniform} and finite despite the presence of a coordinate singularity, the effective density $\\rho_e = \\rho + \\Lambda/8 \\pi =0$, where $\\Lambda$ is the cosmological constant. Under weak energy condition, this would imply $\\rho = \\Lambda =0$ for ESU. This means that if one would need to invoke a source of ``repulsive gravity'' in some model, (i) the model must be non-static, (ii) the repulsive gravity must be due to a ``quintessence'' or a ``dark energy'' fluid with negative pressure and appear on the right hand side (RHS) of the Einstein equation through $T_{ij}$ rather than through a fundamental constant residing on the LHS of the same equation, and (iii) energy density of both normal matter and the ``dark energy fluid'' should be time dependent. In fact, the repulsive gravity would be due to a time independent $\\Lambda$, it would be extremely difficult to understand why the associated energy density should be approximately $10^{120}$ times lower than the value predicted by quantum gravity. On the other hand, for a dark energy fluid whose energy density is time dependent, it would be much easier to understand such an extremely low present energy density: the original initial value of the energy density of the fluid could be equal to the quantum gravity value while the present low value is due to decay with time.

Abhas Mitra

2008-06-04

413

Bose-Einstein Condensation in Extended Microgravity  

NASA Astrophysics Data System (ADS)

The setup and the envisaged experiment timeline of the QUANTUS-III experiment onboard a sounding rocket to be started in the near future are presented. The major intention of QUANTUS-III is the stable generation of a number of Bose-Einstein condensates as a source for atom interferometry during several minutes of microgravity onboard the sounding rocket. Later missions aim at the realization of atom interferoemeters as precursor satellite missions. These condesates will be generated serially, allowing a large number of repeatable tests. Within such Bose-Einstein condensates, millions of atoms lose their identity and can be described by a single macroscopic wave function. During the expansion over several seconds, 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. Cold quantum gases and, in particular, Bose-Einstein condensates represent a new state of matter which is nowadays established in many laboratories. They offer unique insights into a broad range of fundamental physics as well as prospects for novel quantum sensors. Microgravity will substantially extend the science of quantum gases towards nowadays inaccessible regimes at lowest temperatures, to macroscopic dimensions, and to unequalled durations of unperturbed evolution of these distinguished quantum objects. Right now, the QUANTUS-III experiment is in the development phase, taking heritage from QUANTUS-I and QUANTUS-II. Major components of the engineering model are available. Boundary conditions of the rocket, requirements of the experiment and interface considerations are presented. This include laser stabilization, vacuum technology and magnetic shielding. The planned trajectory of the rocket will have an apogee of 200 - 300 km and a total microgravity time of 4 - 7 minutes, both depending on the total experiment mass.

Scharringhausen, Marco; Quantus Team; Rasel, Ernst Maria

2012-07-01

414

Bose-Einstein condensation of sodium atoms  

NASA Astrophysics Data System (ADS)

Bose-Einstein Condensation in an ultracold gas of neutral sodium atoms has been observed and studied. This was achieved utilizing a combination of laser cooling techniques, magnetic trapping and evaporative cooling. A novel tightly confining dc magnetic trap was developed and demonstrated. This trap combines tight confinement with excellent optical access. Evaporative cooling in this trap produced Bose condensates of 5× 106 atoms, a tenfold improvement over previous results. The Bose-Einstein phase transition was studied and characterized by mapping out the condensed fraction as a function of temperature across the transition point. The characteristic mean-field interaction of particles in the condensate was investigated. Collective excitations of a dilute Bose condensate have been observed. These excitations are analogous to phonons in superfluid helium. The frequencies of the lowest modes were studied for a temperature close to 0 K and compared with theoretical predictions based on mean-field theory. The characteristic damping of one of the modes was measured and compared to damping of 'sound waves' in an ultra-cold gas above the Bose-Einstein transition. We have also demonstrated an output coupler for Bose condensed atoms in a magnetic trap. With short rf pulses Bose condensates were put into a superposition of trapped and untrapped hyperfine states. By varying the rf amplitude we could adjust the fraction of outcoupled atoms between 0 and 100%. This source produces pulses of coherent atoms and can be regarded as a pulsed 'atom laser'. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.)

Mewes, Marc-Oliver

1997-10-01

415

Einsteins hole dilemma and gauge freedom  

E-print Network

The issue of the physical equivalence between the different coordinate system in Einstein theory is revised. Gauge fixing influences results of measurements and physics are different in two different coordinate system. Spacetime metric generated by static spherically symmetric distribution of matter can be matched with wide family of vacuum solution and the exterior spacetime geometry could not be deduced directly from the interior perfect fluid solution, without reference to a gauge fixing or viceversa. The property of sollutions in general relativity is indeed an observer dependent concept.

Kozyrev, Sergey M

2012-01-01

416

Multimessenger astronomy with the Einstein Telescope  

E-print Network

Gravitational waves (GWs) are expected to play a crucial role in the development of multimessenger astrophysics. The combination of GW observations with other astrophysical triggers, such as from gamma-ray and X-ray satellites, optical/radio telescopes, and neutrino detectors allows us to decipher science that would otherwise be inaccessible. In this paper, we provide a broad review from the multimessenger perspective of the science reach offered by the third generation interferometric GW detectors and by the Einstein Telescope (ET) in particular. We focus on cosmic transients, and base our estimates on the results obtained by ET's predecessors GEO, LIGO, and Virgo.

Eric Chassande-Mottin; Martin Hendry; Patrick J. Sutton; Szabolcs Márka

2010-04-12

417

Bose-Einstein Condensation of Yb atoms  

SciTech Connect

We could recently achieve the Bose Einstein condensation (BEC) of Yb atoms. Yb differs from most of the elements that have previously been condensed, because it is a two-electron atom with the singlet S ground state. Furthermore the Bosonic isotopes of Yb, like 174Yb which we succeeded to condensate, has no nuclear spin, so that the ground state is completely spin-less state and hence insensitive to magnetic fields. Thus a new type of atom could join the group of atoms for BEC studies. We would like to report how we could achieve the BEC of Yb atoms.

Takasu, Y.; Maki, K.; Komori, K.; Takano, T.; Honda, K.; Kumakura, M.; Yabuzaki, T.; Takahashi, Y. [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan)

2005-05-05

418

Extragalactic counterparts to Einstein slew survey sources  

NASA Technical Reports Server (NTRS)

The Einstein slew survey consists of 819 bright X-ray sources, of which 636 (or 78 percent) are identified with counterparts in standard catalogs. The importance of bright X-ray surveys is stressed, and the slew survey is compared to the Rosat all sky survey. Statistical techniques for minimizing confusion in arcminute error circles in digitized data are discussed. The 238 slew survey active galactic nuclei, clusters, and BL Lacertae objects identified to date and their implications for logN-logS and source evolution studies are described.

Schachter, Jonathan F.; Elvis, Martin; Plummer, David; Remillard, Ron

1992-01-01

419

Phase Standard for Bose-Einstein Condensates  

NASA Astrophysics Data System (ADS)

We discuss how a consistent phase standard for Bose-Einstein condensates may be defined. We show that it has the properties we would wish for in a phase standard: it is not corrupted by subsequent comparisons. A quantum jump technique is employed to study the time evolution of a three mode condensate system on which we make measurements, which entangle the modes and so establish relative phases between them. By establishing, in turn, the phases of two condensates relative to a reference condensate, we show that the relative phase between them can be predicted accurately. The existence of such a phase standard gives a precise definition to the phase of a condensate.

Dunningham, J. A.; Burnett, K.

1999-05-01

420

Strongly hyperbolic second order Einstein's evolution equations  

E-print Network

BSSN-type evolution equations are discussed. The name refers to the Baumgarte, Shapiro, Shibata, and Nakamura version of the Einstein evolution equations, without introducing the conformal-traceless decomposition but keeping the three connection functions and including a densitized lapse. It is proved that a pseudo-differential first order reduction of these equations is strongly hyperbolic. In the same way, densitized Arnowitt-Deser-Misner evolution equations are found to be weakly hyperbolic. In both cases, the positive densitized lapse function and the spacelike shift vector are arbitrary given fields. This first order pseudodifferential reduction adds no extra equations to the system and so no extra constraints.

Gabriel Nagy; Omar E. Ortiz; Oscar A. Reula

2004-02-26

421

Bose-Einstein Condensation of Strontium  

SciTech Connect

We report on the attainment of Bose-Einstein condensation with ultracold strontium atoms. We use the {sup 84}Sr isotope, which has a low natural abundance but offers excellent scattering properties for evaporative cooling. Accumulation in a metastable state using a magnetic-trap, narrowline cooling, and straightforward evaporative cooling in an optical trap lead to pure condensates containing 1.5x10{sup 5} atoms. This puts {sup 84}Sr in a prime position for future experiments on quantum-degenerate gases involving atomic two-electron systems.

Stellmer, Simon; Huang Bo; Grimm, Rudolf [Institut fuer Quantenoptik und Quanteninformation (IQOQI), Oesterreichische Akademie der Wissenschaften, 6020 Innsbruck (Austria); Institut fuer Experimentalphysik und Zentrum fuer Quantenphysik, Universitaet Innsbruck, 6020 Innsbruck (Austria); Tey, Meng Khoon; Schreck, Florian [Institut fuer Quantenoptik und Quanteninformation (IQOQI), Oesterreichische Akademie der Wissenschaften, 6020 Innsbruck (Austria)

2009-11-13

422

Nonequilibrium version of the Einstein relation  

NASA Astrophysics Data System (ADS)

The celebrated Einstein relation between the diffusion coefficient D and the drift velocity v is violated in nonequilibrium circumstances. We analyze how this violation emerges for the simplest example of a Brownian motion on a lattice, taking into account the interplay between the periodicity, the randomness, and the asymmetry of the transition rates. Based on the nonequilibrium fluctuation theorem the v /D ratio is found to be a nonlinear function of the affinity. Hence it depends in a nontrivial way on the microscopics of the sample.

Hurowitz, Daniel; Cohen, Doron

2014-09-01

423

A New Interpretation of Einstein's Cosmological Constant  

E-print Network

A new approach to the cosmological constant problem is proposed by modifying Einstein's theory of general relativity, using instead a scalar-tensor theory of gravitation. This theory of gravity crucially incorporates the concept of quantum symmetry breaking. The role of the cosmological constant $\\lambda$ as a graviton mass in the weak-field limit is necessarily utilized. Because $\\lambda$ takes on two values as a broken symmetry, so does the graviton mass -- one of which cannot be zero. Gravity now exhibits both long- and short-range forces, by introducing hadron bags into strong interaction physics using a nonlinear, self-interacting scalar $\\sigma$-field coupled to the gravitational Lagrangian.

Thomas L. Wilson

2011-10-25

424

Entangled light from Bose-Einstein condensates  

E-print Network

We propose a method to generate entangled light with a Bose-Einstein condensate trapped in a cavity, a system realized in recent experiments. The atoms of the condensate are trapped in a periodic potential generated by a cavity mode. The condensate is continuously pumped by a laser and spontaneously emits a pair of photons of different frequencies in two distinct cavity modes. In this way, the condensate mediates entanglement between two cavity modes which leak out and can be separated and exhibit continuous variable entanglement. The scheme exploits the experimentally demonstrated strong, steady and collective coupling of condensate atoms to a cavity field.

H. T. Ng; S. Bose

2008-09-30

425

Rydberg excitation of Bose-Einstein condensates  

E-print Network

Rydberg atoms provide a wide range of possibilities to tailor interactions in a quantum gas. Here we report on Rydberg excitation of Bose-Einstein condensed 87Rb atoms. The Rydberg fraction was investigated for various excitation times and temperatures above and below the condensation temperature. The excitation is locally blocked by the van der Waals interaction between Rydberg atoms to a density-dependent limit. Therefore the abrupt change of the thermal atomic density distribution to the characteristic bimodal distribution upon condensation could be observed in the Rydberg fraction. The observed features are reproduced by a simulation based on local collective Rydberg excitations.

Rolf Heidemann; Ulrich Raitzsch; Vera Bendkowsky; Björn Butscher; Robert Löw; Tilman Pfau

2007-10-30

426

Bose-Einstein condensation on quantum graphs  

E-print Network

We present results on Bose-Einstein condensation (BEC) on general compact quantum graphs, i.e., one-dimensional systems with a (potentially) complex topology. We first investigate non-interacting many-particle systems and provide a complete classification of systems that exhibit condensation. We then consider models with interactions that consist of a singular part as well as a hardcore part. In this way we obtain generalisations of the Tonks-Girardeau gas to graphs. For this we find an absence of phase transitions which then indicates an absence of BEC.

Jens Bolte; Joachim Kerner

2014-03-02

427

SUMMER/FALL 2012 The Magazine for Alumni and Friends of Albert Einstein College of Medicine of Yeshiva University  

E-print Network

EINSTEIN SUMMER/FALL 2012 The Magazine for Alumni and Friends of Albert Einstein College and supporters of Albert Einstein College of Medicine of Yeshiva University Published by The Philip and Rita-mail: letters@einstein.yu.edu Website: www.einstein.yu.edu Copyright © 2012 Albert Einstein College of Medicine

Kenny, Paraic

428

SPRING/SUMMER 2013 The Magazine for Alumni and Friends of Albert Einstein College of Medicine of Yeshiva University  

E-print Network

EINSTEIN SPRING/SUMMER 2013 The Magazine for Alumni and Friends of Albert Einstein College The magazine for alumni, faculty, students, friends and supporters of Albert Einstein College of Medicine-mail: letters@einstein.yu.edu Website: www.einstein.yu.edu Copyright © 2013 Albert Einstein College of Medicine

Kenny, Paraic

429

A primer on the (2+1) Einstein universe  

E-print Network

The Einstein universe is the conformal compactification of Minkowski space. It also arises as the ideal boundary of anti-de Sitter space. The purpose of this article is to develop the synthetic geometry of the Einstein universe in terms of its homogeneous submanifolds and causal structure, with particular emphasis on dimension $2 + 1$, in which there is a rich interplay with symplectic geometry.

Barbot, Thierry; Drumm, Todd; Goldman, William M; Melnick, Karin

2007-01-01

430

Einsteins Arbeiten in Bezug auf die moderne Kosmologie  

E-print Network

We comment on the paper [1] by Albert Einstein from 1918 to Willem De Sitter's solution [2] of the Einstein field equation from today's point of view. To this end, we start by describing the geometry of the De Sitter space-time and present its importance for the inflationary cosmological model.

H. -J. Schmidt

2005-06-25

431

Albert Einstein's 1916 Review Article on General Relativity  

Microsoft Academic Search

The first comprehensive overview of the final version of the general theory of relativity was published by Einstein in 1916 after several expositions of preliminary versions and latest revisions of the theory in November 1915. A historical account of this review paper is given, of its prehistory, including a discussion of Einstein's collaboration with Marcel Grossmann, and of its immediate

Tilman Sauer; Einstein Papers Project

2004-01-01

432

Albert Einstein's 1916 Review Article on General Relativity  

E-print Network

The first comprehensive overview of the final version of the general theory of relativity was published by Einstein in 1916 after several expositions of preliminary versions and latest revisions of the theory in November 1915. A historical account of this review paper is given, of its prehistory, including a discussion of Einstein's collaboration with Marcel Grossmann, and of its immediate reception.

Tilman Sauer

2004-05-13

433

Muriel L. Block Bequeaths Largest Gift in Einstein History  

E-print Network

research. But the story of Muriel's devo- tion to Einstein does not end there, because she named Albert5 Muriel L. Block Bequeaths Largest Gift in Einstein History Inspired by her belief and an indelible legacy F or decades, Muriel L. Block was a passionate supporter of medical research at Albert

Yates, Andrew

434

A comparative analysis of perspectives of Mileva Maric Einstein  

Microsoft Academic Search

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

Carol C. Barnett

1998-01-01

435

From the Classroom to Washington: Einsteins on Education Reform  

ERIC Educational Resources Information Center

The Woodrow Wilson International Center for Scholars was delighted to host a group of current and former Albert Einstein Distinguished Educator Fellows as they celebrated the 20th anniversary of the fellowship program. Outstanding math and science teachers in America's K-12 schools, the Einstein Fellows spend a year (or sometimes two) working on…

Hughes, Kent H., Ed.; Byers, Elizabeth A., Ed.

2010-01-01

436

Static self-gravitating elastic bodies in Einstein gravity  

E-print Network

We prove that given a stress-free elastic body there exists, for sufficiently small values of the gravitational constant, a unique static solution of the Einstein equations coupled to the equations of relativistic elasticity. The solution constructed is a small deformation of the relaxed configuration. This result yields the first proof of existence of static solutions of the Einstein equations without symmetries.

Lars Andersson; Robert Beig; Bernd Schmidt

2006-11-20

437

Quantum Mechanics of the Einstein-Hopf Model.  

ERIC Educational Resources Information Center

The Einstein-Hopf model for the thermodynamic equilibrium between the electromagnetic field and dipole oscillators is considered within the framework of quantum mechanics. Both the wave and particle aspects of the Einstein fluctuation formula are interpreted in terms of the fundamental absorption and emission processes. (Author/SK)

Milonni, P. W.

1981-01-01

438

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

Microsoft Academic Search

'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

Jeffrey Crelinsten

2007-01-01

439

A Note On Einstein, Bergmann, and the Fifth Dimension  

E-print Network

This note is devoted to a detail concerning the work of Albert Einstein and Peter Bergmann on unified theories of electromagnetism and gravitation in five dimensions. In their paper of 1938, Einstein and Bergmann were among the first to introduce the modern viewpoint in which a four-dimensional theory that coincides with Einstein-Maxwell theory at long distances is derived from a five-dimensional theory with complete symmetry among all five dimensions. But then they drew back, modifying the theory in a way that spoiled the five-dimensional symmetry and looks contrived to modern readers. Why? According to correspondence of Peter Bergmann with the author, the reason was that the more symmetric version of the theory predicts the existence of a new long range field (a massless scalar field). In 1938, Einstein and Bergmann did not wish to make this prediction. (Based on a lecture at the Einstein Centennial Celebration at the Library of Alexandria, June, 2005.

Witten, Edward

2014-01-01

440

Lie Symmetries of Einstein's Vacuum Equations in N Dimensions  

E-print Network

We investigate Lie symmetries of Einstein's vacuum equations in N dimensions, with a cosmological term. For this purpose, we first write down the second prolongation of the symmetry generating vector fields, and compute its action on Einstein's equations. Instead of setting to zero the coefficients of all independent partial derivatives (which involves a very complicated substitution of Einstein's equations), we set to zero the coefficients of derivatives that do not appear in Einstein's equations. This considerably constrains the coefficients of symmetry generating vector fields. Using the Lie algebra property of generators of symmetries and the fact that general coordinate transformations are symmetries of Einstein's equations, we are then able to obtain all the Lie symmetries. The method we have used can likely be applied to other types of equations.

Louis Marchildon

1997-01-20

441

Nearfield Electromagnetic Effects on Einstein Special Relativity  

E-print Network

In this paper Maxwell equations are used to analyze the propagation of oscillating electric and magnetic fields from a moving electric dipole source. The results show that both the magnetic field and electric fields generated propagate faster than the speed of light in the nearfield and reduce to the speed of light as they propagate into the farfield of the source. In addition, the results show that the speed of the fields are dependant on the velocity of the source in the nearfield and only become independent in the farfield. These effects are shown to be the same whether the source or observation point is moving. Because these effects conflict with the assumptions on which Einstein's theory of special relativity theory is based, relativity theory is reanalyzed. The analysis shows that the relativistic gamma factor is dependant on whether the analysis is performed using nearfield or farfield propagating EM fields. In the nearfield, gamma is approximately one indicating that the coordinate transforms are Galilean in the nearfield. In the farfield the gamma factor reduces to the standard known relativistic formula indicating that they are approximately valid in the farfield. Because time dilation and space contraction depend on whether nearfield or farfield propagating fields are used in their analysis, it is proposed that Einstein relativistic effects are an illusion created by the propagating EM fields used in their measurement. Instead space and time are proposed to not be flexible as indicated by Galilean relativity.

William D. Walker

2007-02-20

442

From Navier-Stokes To Einstein  

E-print Network

We show by explicit construction that for every solution of the incompressible Navier-Stokes equation in $p+1$ dimensions, there is a uniquely associated "dual" solution of the vacuum Einstein equations in $p+2$ dimensions. The dual geometry has an intrinsically flat timelike boundary segment $\\Sigma_c$ whose extrinsic curvature is given by the stress tensor of the Navier-Stokes fluid. We consider a "near-horizon" limit in which $\\Sigma_c$ becomes highly accelerated. The near-horizon expansion in gravity is shown to be mathematically equivalent to the hydrodynamic expansion in fluid dynamics, and the Einstein equation reduces to the incompressible Navier-Stokes equation. For $p=2$, we show that the full dual geometry is algebraically special Petrov type II. The construction is a mathematically precise realization of suggestions of a holographic duality relating fluids and horizons which began with the membrane paradigm in the 70's and resurfaced recently in studies of the AdS/CFT correspondence.

Irene Bredberg; Cynthia Keeler; Vyacheslav Lysov; Andrew Strominger

2011-01-12

443

Data Analysis Challenges for the Einstein Telescope  

E-print Network

The Einstein Telescope is a proposed third generation gravitational wave detector that will operate in the region of 1 Hz to a few kHz. As well as the inspiral of compact binaries composed of neutron stars or black holes, the lower frequency cut-off of the detector will open the window to a number of new sources. These will include the end stage of inspirals, plus merger and ringdown of intermediate mass black holes, where the masses of the component bodies are on the order of a few hundred solar masses. There is also the possibility of observing intermediate mass ratio inspirals, where a stellar mass compact object inspirals into a black hole which is a few hundred to a few thousand times more massive. In this article, we investigate some of the data analysis challenges for the Einstein Telescope such as the effects of increased source number, the need for more accurate waveform models and the some of the computational issues that a data analysis strategy might face.

Leone Bosi; Edward K. Porter

2009-10-02

444

Einstein Light: A Brief Illumination of Relativity  

NSDL National Science Digital Library

With endorsements from both Scientific American and Science magazines, this website developed by The University of New South Wales is gaining currency among those interested in using the web for educational purposes. The basic mission of the Einstein Light site is to present a brief overview of EinsteinâÂÂs theory of relativity and its relationship to the work done by Galileo and Newton. This of course means they must address such thorny topics as time dilation and length contraction. They do just that, with the assistance of two animated models, Zoe and Jasper. Throughout the various modules presented here, the two models provide the means by which the casual visitor can begin to understand these concepts. Visitors may also appreciate the fact that there are also a number of related links offered here for further edification. Some of the sections here include âÂÂElectricity and magnetism in a moving frame: what would you expect?â and âÂÂIs time dilation true?âÂÂ. Overall, this is a well-designed site that will be of interest to those with a general interest in this subject and for educators as well.

2005-01-01

445

Newton to Einstein — dust to dust  

NASA Astrophysics Data System (ADS)

We investigate the relation between the standard Newtonian equations for a pressureless fluid (dust) and the Einstein equations in a double expansion in small scales and small metric perturbations. We find that parts of the Einstein equations can be rewritten as a closed system of two coupled differential equations for the scalar and transverse vector metric perturbations in Poisson gauge. It is then shown that this system is equivalent to the Newtonian system of continuity and Euler equations. Brustein and Riotto (2011) conjectured the equivalence of these systems in the special case where vector perturbations were neglected. We show that this approach does not lead to the Euler equation but to a physically different one with large deviations already in the 1-loop power spectrum. We show that it is also possible to consistently set to zero the vector perturbations which strongly constrains the allowed initial conditions, in particular excluding Gaussian ones such that inclusion of vector perturbations is inevitable in the cosmological context. In addition we derive nonlinear equations for the gravitational slip and tensor perturbations, thereby extending Newtonian gravity of a dust fluid to account for nonlinear light propagation effects and dust-induced gravitational waves.

Kopp, Michael; Uhlemann, Cora; Haugg, Thomas

2014-03-01

446

Radiation Damping in Einstein-Aether Theory  

E-print Network

This work concerns the loss of energy of a material system due to gravitational radiation in Einstein-aether theory-an alternative theory of gravity in which the metric couples to a dynamical, timelike, unit-norm vector field. Derived to lowest post-Newtonian order are waveforms for the metric and vector fields far from a nearly Newtonian system and the rate of energy radiated by the system. The expressions depend on the quadrupole moment of the source, as in standard general relativity, but also contain monopolar and dipolar terms. There exists a one-parameter family of Einstein-aether theories for which only the quadrupolar contribution is present, and for which the expression for the damping rate is identical to that of general relativity to the order worked to here. This family cannot yet be declared observationally viable, since effects due to the strong internal fields of bodies in the actual systems used to test the damping rate are not included.

Brendan Z. Foster

2006-02-01

447

Bose-Einstein condensation in quantum magnets  

NASA Astrophysics Data System (ADS)

This article reviews experimental and theoretical work on Bose-Einstein condensation in quantum magnets. These magnets are natural realizations of gases of interacting bosons whose relevant parameters such as dimensionality, lattice geometry, amount of disorder, nature of the interactions, and particle concentration can vary widely between different compounds. The particle concentration can be easily tuned by applying an external magnetic field which plays the role of a chemical potential. This rich spectrum of realizations offers a unique possibility for studying the different physical behaviors that emerge in interacting Bose gases from the interplay between their relevant parameters. The plethora of other bosonic phases that can emerge in quantum magnets, of which the Bose-Einstein condensate is the most basic ground state, is reviewed. The compounds discussed in this review have been intensively studied in the last two decades and have led to important contributions in the area of quantum magnetism. In spite of their apparent simplicity, these systems often exhibit surprising behaviors. The possibility of using controlled theoretical approaches has triggered the discovery of unusual effects induced by frustration, dimensionality, or disorder.

Zapf, Vivien; Jaime, Marcelo; Batista, C. D.

2014-04-01

448

Dynamic hyporheic exchange at intermediate timescales: testing the relative importance of evapotranspiration and flood pulses  

USGS Publications Warehouse

Hyporheic fluxes influence ecological processes across a continuum of timescales. However, few studies have been able to characterize hyporheic fluxes and residence time distributions (RTDs) over timescales of days to years, during which evapotranspiration (ET) and seasonal flood pulses create unsteady forcing. Here we present a data-driven, particle-tracking piston model that characterizes hyporheic fluxes and RTDs based on measured vertical head differences. We used the model to test the relative influence of ET and seasonal flood pulses in the Everglades (FL, USA), in a manner applicable to other low-energy floodplains or broad, shallow streams. We found that over the multiyear timescale, flood pulses that drive relatively deep (?1 m) flow paths had the dominant influence on hyporheic fluxes and residence times but that ET effects were discernible at shorter timescales (weeks to months) as a break in RTDs. Cumulative RTDs on either side of the break were generally well represented by lognormal functions, except for when ET was strong and none of the standard distributions applied to the shorter timescale. At the monthly timescale, ET increased hyporheic fluxes by 1–2 orders of magnitude; it also decreased 6 year mean residence times by 53–87%. Long, slow flow paths driven by flood pulses increased 6 year hyporheic fluxes by another 1–2 orders of magnitude, to a level comparable to that induced over the short term by shear flow in streams. Results suggest that models of intermediate-timescale processes should include at least two-storage zones with different RTDs, and that supporting field data collection occur over 3–4 years.

Larsen, Laurel G.; Harvey, Judson W.; Maglio, Morgan M.

2014-01-01

449

Timescales of Quartz Crystallization and the Longevity of the Bishop Giant Magma Body  

PubMed Central

Supereruptions violently transfer huge amounts (100 s–1000 s km3) of magma to the surface in a matter of days and testify to the existence of giant pools of magma at depth. The longevity of these giant magma bodies is of significant scientific and societal interest. Radiometric data on whole rocks, glasses, feldspar and zircon crystals have been used to suggest that the Bishop Tuff giant magma body, which erupted ?760,000 years ago and created the Long Valley caldera (California), was long-lived (>100,000 years) and evolved rather slowly. In this work, we present four lines of evidence to constrain the timescales of crystallization of the Bishop magma body: (1) quartz residence times based on diffusional relaxation of Ti profiles, (2) quartz residence times based on the kinetics of faceting of melt inclusions, (3) quartz and feldspar crystallization times derived using quartz+feldspar crystal size distributions, and (4) timescales of cooling and crystallization based on thermodynamic and heat flow modeling. All of our estimates suggest quartz crystallization on timescales of <10,000 years, more typically within 500–3,000 years before eruption. We conclude that large-volume, crystal-poor magma bodies are ephemeral features that, once established, evolve on millennial timescales. We also suggest that zircon crystals, rather than recording the timescales of crystallization of a large pool of crystal-poor magma, record the extended periods of time necessary for maturation of the crust and establishment of these giant magma bodies. PMID:22666359

Gualda, Guilherme A. R.; Pamukcu, Ayla S.; Ghiorso, Mark S.; Anderson, Alfred T.; Sutton, Stephen R.; Rivers, Mark L.

2012-01-01

450

Timescales of quartz crystallization and the longevity of the Bishop giant magma body.  

PubMed

Supereruptions violently transfer huge amounts (100 s-1000 s km(3)) of magma to the surface in a matter of days and testify to the existence of giant pools of magma at depth. The longevity of these giant magma bodies is of significant scientific and societal interest. Radiometric data on whole rocks, glasses, feldspar and zircon crystals have been used to suggest that the Bishop Tuff giant magma body, which erupted ~760,000 years ago and created the Long Valley caldera (California), was long-lived (>100,000 years) and evolved rather slowly. In this work, we present four lines of evidence to constrain the timescales of crystallization of the Bishop magma body: (1) quartz residence times based on diffusional relaxation of Ti profiles, (2) quartz residence times based on the kinetics of faceting of melt inclusions, (3) quartz and feldspar crystallization times derived using quartz+feldspar crystal size distributions, and (4) timescales of cooling and crystallization based on thermodynamic and heat flow modeling. All of our estimates suggest quartz crystallization on timescales of <10,000 years, more typically within 500-3,000 years before eruption. We conclude that large-volume, crystal-poor magma bodies are ephemeral features that, once established, evolve on millennial timescales. We also suggest that zircon crystals, rather than recording the timescales of crystallization of a large pool of crystal-poor magma, record the extended periods of time necessary for maturation of the crust and establishment of these giant magma bodies. PMID:22666359

Gualda, Guilherme A R; Pamukcu, Ayla S; Ghiorso, Mark S; Anderson, Alfred T; Sutton, Stephen R; Rivers, Mark L

2012-01-01

451

Timescales of Quartz Crystallization and the Longevity of the Bishop Giant Magma Body  

SciTech Connect

Supereruptions violently transfer huge amounts (100 s-1000 s km{sup 3}) of magma to the surface in a matter of days and testify to the existence of giant pools of magma at depth. The longevity of these giant magma bodies is of significant scientific and societal interest. Radiometric data on whole rocks, glasses, feldspar and zircon crystals have been used to suggest that the Bishop Tuff giant magma body, which erupted {approx}760,000 years ago and created the Long Valley caldera (California), was long-lived (>100,000 years) and evolved rather slowly. In this work, we present four lines of evidence to constrain the timescales of crystallization of the Bishop magma body: (1) quartz residence times based on diffusional relaxation of Ti profiles, (2) quartz residence times based on the kinetics of faceting of melt inclusions, (3) quartz and feldspar crystallization times derived using quartz+feldspar crystal size distributions, and (4) timescales of cooling and crystallization based on thermodynamic and heat flow modeling. All of our estimates suggest quartz crystallization on timescales of <10,000 years, more typically within 500-3,000 years before eruption. We conclude that large-volume, crystal-poor magma bodies are ephemeral features that, once established, evolve on millennial timescales. We also suggest that zircon crystals, rather than recording the timescales of crystallization of a large pool of crystal-poor magma, record the extended periods of time necessary for maturation of the crust and establishment of these giant magma bodies.

Gualda, Guilherme A.R.; Pamukcu, Ayla S.; Ghiorso, Mark S.; Anderson, Jr. , Alfred T.; Sutton, Stephen R.; Rivers, Mark L. (OFM Res.); (Vanderbilt); (UC)

2013-04-08

452

When champions meet: Rethinking the Bohr--Einstein debate  

E-print Network

Einstein's philosophy of physics (as clarified by Fine, Howard, and Held) was predicated on his Trennungsprinzip, a combination of separability and locality, without which he believed objectification, and thereby "physical thought" and "physical laws", to be impossible. Bohr's philosophy (as elucidated by Hooker, Scheibe, Folse, Howard, Held, and others), on the other hand, was grounded in a seemingly different doctrine about the possibility of objective knowledge, namely the necessity of classical concepts. In fact, it follows from Raggio's Theorem in algebraic quantum theory that - within an appropriate class of physical theories - suitable mathematical translations of the doctrines of Bohr and Einstein are equivalent. Thus - upon our specific formalization - quantum mechanics accommodates Einstein's Trennungsprinzip if and only if it is interpreted a la Bohr through classical physics. Unfortunately, the protagonists themselves failed to discuss their differences in this constructive way, since their debate was dominated by Einstein's ingenious but ultimately flawed attempts to establish the "incompleteness" of quantum mechanics. This aspect of their debate may still be understood and appreciated, however, as reflecting a much deeper and insurmountable disagreement between Bohr and Einstein on the knowability of Nature. Using the theological controversy on the knowability of God as a analogy, Einstein was a Spinozist, whereas Bohr could be said to be on the side of Maimonides. Thus Einstein's off-the-cuff characterization of Bohr as a 'Talmudic philosopher' was spot-on.

N. P. Landsman

2005-07-22

453

Microphysical Timescales in Clouds and their Application in Cloud-Resolving Modeling  

NASA Technical Reports Server (NTRS)

Computational phenomena (i.e., spurious supersaturation and negative mixing ratio of cloud water) usually exist in cloud-resolving models when the time step for explicit integration is larger than a microphysical timescale in clouds. In this paper, the microphysical timescales in clouds are studied, showing that the timescale of water vapor condensation (or cloud water evaporation) is smaller than 10 s - the order of a typical time step for cloud-resolving models. To avoid spurious computational phenomena in cloud-resolving modeling, it is suggested that moist entropy be used as a prognostic thermodynamic variable, and temperature be diagnosed from that and other prognostic variables. A simple numerical model with moist entropy as a prognostic variable, for example, is presented to show that spurious computational phenomena are removed when moist entropy is used as a prognostic variable.

Zeng, Xi-Ping; Tao, Wei-Kuo; Simpson, Joanne

2004-01-01

454

Nonminimal Einstein-Maxwell-Vlasov-axion model  

E-print Network

We establish a new self-consistent system of equations accounting for a nonminimal coupling of the cooperative gravitational, electromagnetic and pseudoscalar (axion) fields in a multi-component relativistic plasma. The axionic extension of the nonminimal Einstein-Maxwell-Vlasov theory is based on two consistent procedures. First, we use the Lagrange formalism to obtain nonminimal equations for the gravitational, electromagnetic and pseudoscalar fields with the additional sources generated in plasma. Second, we use the Vlasov version of the relativistic kinetic theory of the plasma, guided by the cooperative macroscopic electromagnetic, gravitational and axionic fields, to describe adequately the response of the plasma on the variations of these fields. In order to show the self-consistency of this approach we check directly the compatibility conditions for the master equations for the cooperative fields. Using these compatibility conditions we reconstruct the ponderomotive force, which acts on the plasma par...

Balakin, Alexander B; Zayats, Alexei E

2014-01-01

455

Bye Bye Blackboard: From Einstein and others  

NSDL National Science Digital Library

Educational theorists, professors, and other such types have long predicted the demise of the blackboard in the classroom. While many remain skeptical of other forms of transmitting knowledge (such as the use of tools such as PowerPoint and the like), it is certainly true that blackboards are disappearing from many classrooms. With that in mind, the Museum of the History of Science at the University of Oxford has created this online exhibit that pays tribute to the blackboard and its many uses. Visitors to the site can view eighteen different blackboards from contributors that include Albert Einstein, Brian Eno, Glenda Jackson, and Alain de Botton. Visitors can view large images of each blackboard and its contents and also view some brief commentary from each contributor.

2005-01-01

456

Equivalence of the Einstein and Jordan frames  

NASA Astrophysics Data System (ADS)

No experiment can measure an absolute scale: every dimensionful quantity has to be compared to some fixed unit scale in order to be measured, and thus only dimensionless quantities are really physical. The Einstein and Jordan frames are related by a conformal transformation of the metric, which amounts to rescaling all length scales. Since the absolute scale cannot be measured, both frames describe the same physics and are equivalent. In this article we make this explicit by rewriting the action in terms of dimensionless variables, which are invariant under a conformal transformation. For definitiveness, we concentrate on the action of Higgs inflation, but the results can easily be generalized. In addition, we show that the action for f (R ) gravity, which includes Starobinsky inflation, can be written in a frame-independent form.

Postma, Marieke; Volponi, Marco

2014-11-01

457

Energy in the Einstein-Aether Theory  

E-print Network

We investigate the energy of a theory with a unit vector field (the "aether") coupled to gravity. Both the Weinberg and Einstein type energy-momentum pseudotensors are employed. In the linearized theory we find expressions for the energy density of the 5 wave modes. The requirement that the modes have positive energy is then used to constrain the theory. In the fully non-linear theory we compute the total energy of an asymptotically flat spacetime. The resulting energy expression is modified by the presence of the aether due to the non-zero value of the unit vector at infinity and its 1/r falloff. The question of non-linear energy positivity is also discussed, but not resolved.

Christopher Eling

2005-07-14

458

Fidelity of a Bose Einstein condensates  

NASA Astrophysics Data System (ADS)

We investigate fidelity for the quantum evolution of a Bose Einstein condensate and reveal its general property with a simple model. We find the fidelity decay with time in various ways depending on the form of initial states as well as on mean-field dynamics. When the initial state is a coherent state, the fidelity decays with time in the ways of exponential, Gaussian, and power-law, having a close relation to the classical mean-field dynamics. With the initial state prepared as a maximally entangled state, we find the behavior of fidelity has no classical correspondence and observe a novel behavior of the fidelity: periodic revival, where the period is inversely proportional to the number of bosons and the perturbation strength. An experimental observation of the fidelity decay is suggested.

Liu, Jie; Wang, Wenge; Zhang, Chuanwei; Niu, Qian; Li, Baowen

2006-04-01

459

Neutron stars in Einstein-aether theory  

SciTech Connect

As current and future experiments probe strong gravitational regimes around neutron stars and black holes, it is desirable to have theoretically sound alternatives to general relativity against which to test observations. Here we study the consequences of one such generalization, Einstein-aether theory, for the properties of nonrotating neutron stars. This theory has a parameter range that satisfies all current weak-field tests. We find that within this range it leads to lower maximum neutron star masses, as well as larger surface redshifts at a particular mass, for a given nuclear equation of state. For nonrotating black holes and neutron stars, the innermost stable circular orbit is only slightly modified in this theory.

Eling, Christopher; Jacobson, Ted [Department of Physics, University of Maryland, College Park, Maryland 20742-4111 (United States); Miller, M. Coleman [Department of Astronomy, University of Maryland, College Park, Maryland 20742-4111 (United States)

2007-08-15

460

WHEN ATOMS BEHAVE AS WAVES: BOSE-EINSTEIN CONDENSATION AND THE ATOM LASER  

E-print Network

of Bose-Einstein condensation was predicted long ago, in a 1925 paper by Albert Einstein [1] usingWHEN ATOMS BEHAVE AS WAVES: BOSE-EINSTEIN CONDENSATION AND THE ATOM LASER Nobel Lecture, December 8, such as Bose-Einstein condensates first realized in 1995. Each of these achievements in cooling has been

461

0.5setgray00.5setgray1 Bose-Einstein condensates in optical lattices  

E-print Network

"? Predicted 1924 Albert Einstein Satiendra Nath Bose ­ p. 3/3 #12;What is a "Bose-Einstein condensate0.5setgray00.5setgray1 Bose-Einstein condensates in optical lattices: mathematical analysis ­ p. 1/3 #12;What is a "Bose-Einstein condensate"? http : //www.colorado.edu/physics/2000/bec/ "It

Cipolatti, Rolci

462

For more information about EEL and the My Einstein Circle, please contact  

E-print Network

cancer's deadly spread · The Albert Einstein Cancer Center incorporates 18 academic departments EMERGING LEADERS Albert Einstein College of Medicine of Yeshiva University is one of the nation's premierFor more information about EEL and the My Einstein Circle, please contact eel@einstein

Yates, Andrew

463

Einstein's View of God Nancy Ellen Abrams and Joel R. Primack  

E-print Network

Einstein's View of God Nancy Ellen Abrams and Joel R. Primack Did Albert Einstein believe in God way, they are part of a search that Einstein began ­ the search for language to communicate the sacred, it was spiritually unacceptable to Einstein that the ultimate nature of reality was randomness. "The [quantum] theory

California at Santa Cruz, University of

464

Nobel lecture: When atoms behave as waves: Bose-Einstein condensation and the atom laser*  

E-print Network

by Albert Einstein (Einstein, 1925b) using a method introduced by Satyen- dra Nath Bose to derive the blackNobel lecture: When atoms behave as waves: Bose-Einstein condensation and the atom laser* Wolfgang, such as Bose-Einstein con- densates first realized in 1995. Each of these achieve- ments in cooling has been

465

What about Albert Einstein? Using Biographies to Promote Students' Scientific Thinking  

ERIC Educational Resources Information Center

Who hasn't heard of Einstein? Science educators everywhere are familiar with Einstein's genius and general theory of relativity. Students easily recognize Einstein's image by his white flyaway hair and bushy mustache. It is well known that Einstein was a brilliant physicist and an abstract thinker who often used his creativity and imagination in…

Fingon, Joan C.; Fingon, Shallon D.

2009-01-01

466

Spatial and seasonal variability of the air-sea equilibration timescale of carbon dioxide  

NASA Astrophysics Data System (ADS)

The exchange of carbon dioxide between the ocean and the atmosphere tends to bring near-surface waters toward equilibrium by reducing the partial pressure gradient across the air-water interface. However, the equilibration process is not instantaneous; in general there is a lag between forcing and response. The timescale of air-sea equilibration depends on several factors involving the depth of the mixed layer, temperature, salinity, wind speed, and carbonate chemistry. In this work, we use a suite of observational datasets to generate climatological and seasonal composite maps of the air-sea equilibration timescale. The relaxation timescale exhibits considerable spatial and seasonal variations, which are largely set by changes in mixed layer depth and wind speed. The net effect is dominated by the mixed layer depth; the gas exchange velocity and carbonate chemistry parameters only provide partial compensation. Broadly speaking, the adjustment timescale tends to increase with latitude. We compare the observationally-derived air-sea gas exchange timescale with a model-derived surface residence time and a data-derived horizontal transport timescale, which allows us to define two non-dimensional metrics of gas exchange efficiency. These parameters highlight the Southern Ocean, equatorial Pacific, and North Atlantic as regions of inefficient air-sea equilibration where carbon anomalies are likely to form and persist. The efficiency parameters presented here can serve as simple tools for understanding regional air-sea disequilibrium in both observations and models. This work is distributed under the Creative Commons Attribution 3.0 Unported License together with an author copyright. This license does not conflict with the regulations of the Crown Copyright.

Jones, Daniel; Ito, Takamitsu; Takano, Yohei; Hsu, Wei-Ching

2014-05-01

467

Planck radiation law and Einstein coefficients reexamined in Kaniadakis ? statistics.  

PubMed

Blackbody radiation is reconsidered using the counterpart of the Bose-Einstein distribution in the ? statistics arising from the Kaniadakis entropy. The generalized Planck radiation law is presented and compared to the usual law, to which it reduces in the limiting case ??0. Effective Einstein's coefficients of emission and absorption are defined in terms of the Kaniadakis parameter ?. It is shown that the Kaniadakis statistics keeps unchanged the first Einstein coefficient A while the second coefficient B admits a generalized form within the present theoretical framework. PMID:25019747

Ourabah, Kamel; Tribeche, Mouloud

2014-06-01

468

Stability of Einstein Static Universe over Lyra Geometry  

E-print Network

The existence and stability conditions of Einstein static universe against homogeneous scalar perturbations in the context of Lyra geometry is investigated. The stability condition is obtained in terms of the constant equation of state parameter $\\omega=p/\\rho$ depending on energy density $\\rho_0$ and scale factor $a_0$ of the initial Einstein static universe. Also, the stability against vector and tensor perturbations is studied. It is shown that a stable Einstein static universe can be found in the context of Lyra geometry against scalar, vector and tensor perturbations for suitable range and values of physical parameters.

F. Darabi; Y. Heydarzade; F. Hajkarim

2014-06-30

469

Albert Einstein's close friends and colleagues from the Patent Office  

E-print Network

In the Patent Office Einstein hatched his most beautiful ideas, and there he spent his "Happy Bern Years". These wonderful ideas led to his miraculous year works of 1905. Einstein was not an expert in academic matters, and he was out of academic world. Neither did he meet influential professors, or attend academic meetings. He discussed his ideas with his close friends and colleagues from the Patent Office. In 1907 he finally got his foot into the academic doorway; Einstein became a privatdozent and gave lectures at the University of Bern. However, his first students consisted again of his two close friends and another colleague from the Patent Office.

Weinstein, Galina

2012-01-01