共查询到20条相似文献，搜索用时 31 毫秒
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Mustafa Saltı 《Astrophysics and Space Science》2006,306(4):201-204
We use the teleparallel geometry analog of the Møller energy-momentum complex to calculate the energy distribution (due to matter plus field including gravity) of a charged black hole solution in heterotic string theory. We find the same energy distribution as obtained by Gad who investigated the same problem by using the Møller energy-momentum complex in general relativity. The total energy depends on the black hole mass M and charge Q. The energy obtained is also independent of the teleparallel dimensionless coupling constant, which means that it is valid not only in the teleparallel equivalent of general relativity, but also in any teleparallel model. Furthermore, our results also sustains (a) the importance of the energy-momentum definitions in the evaluation of the energy distribution of a given spacetime and (b) the viewpoint of Lessner that the Møller energy-momentum complex is a powerful concept of energy and momentum. 相似文献
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David F. Roscoe 《Astrophysics and Space Science》1995,227(1-2):119-132
It is shown that global four-momentum conservation provides all the necessary structure toderive a metric gravity theory which conforms to the requirements of the Strong Equivalence Principle (Will, 1981), and which satisfies all empirical tests up to, and including, those derived from the binary pulsar measurements. Significant consequences arising from this theory are: concepts of curved spacetimes become strictly superfluous to the function of describing gravitational physics; gravitational processes become direct particle/particle interactions; these interactions are arbitrated by wave processes of a kind familiar in electromagnetism; gravitational waves carry energy-momentum in the direction of their propogation vector; the essential singularities at gravitational origins, which are features of both Newtonian gravitation and General Relativity, do not exist. 相似文献
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Gamal G. L. Nashed 《Astrophysics and Space Science》2011,333(1):317-325
We derive three different solutions in the framework of the teleparallel equivalent of general relativity (TEGR). We apply
the energy-momentum tensor to calculate energy, irreducible mass, spatial momentum and angular-momentum associated with these
solutions. We obtain anomalous physical results therefore, we calculate the Killing vectors using the definition of the Lie
derivative. 相似文献
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Gamal G. L. Nashed 《Astrophysics and Space Science》2010,330(2):367-372
We apply the energy-momentum tensor which is coordinate independent, of the gravitational field established in the Hamiltonian structure of the teleparallel equivalent of general relativity (TEGR), to an axially symmetric tetrad field to calculate energy, momentum and angular momentum. Also the definition of the gravitational energy is used to investigate the energy within the external event horizon of this tetrad. 相似文献
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We calculate the energy density and energy distribution of Kantowski-Sachs space-time, using Einstein, Bergmann-Thomson and
Landau-Lifshitz energy-momentum complexes, in the theory of teleparallel gravity. A comparison of the results shows that the
Einstein and Bergmann-Thomson definitions furnish a consistent result for the energy density and energy distribution, but
the definition of Landau-Lifshitz does not concur with them. We show that the space-time under consideration gives a counterexample
that the energy distribution is the same either in general relativity or teleparallel gravity. 相似文献
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In this paper, we utilize the teleparallel gravity analogs of the energy and momentum definitions of Bergmann-Thomson and
Landau-Lifshitz in order to explicitly evaluate the energy distribution (due to matter and fields including gravity) based
on the Bonnor space-time, it is shown that for a stationary beam of light, these energy-momentum definitions give the same
result. Furthermore, this result supports the viewpoint of Cooperstock and also agree with the previous works by Bringley
and Gad. 相似文献
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Alternatives to General Relativity with respect to its causal structure are deeply connected with Mach's hypothesis of the cosmic origin of inertial properties. We consider the main features of a theoretical scheme to construct such alternatives and show that observable effects may be estimated without full construction of a theory. From the point of these alternatives, the light cone of Special Relativity is highly degenerated, and any deviation from General Relativity in the direction considered will reduce this degeneracy. Therefore the effects possible in the alternatives considered provide tests already on the level of Special Relativity. 相似文献
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时间、距离、速度、红移基本物理概念的演变简史 总被引：1，自引：0，他引：1
为了尝试回答“我们能否观测到退行速度超过光速的星系”这一问题,重新考察了在牛顿物理学、狭义相对论、广义相对论和宇宙学中的时伺、距离、速度和红移等概念．揭开了一些错误观念的实质,发现只要摆脱狭义相对论先入为主的束缚,上述问题即可迎刃而解．强调了宇宙学并不是纯粹的广义相对论,而是该理论在服从宇宙学原理的条件下的一个特例,其中一系列基本物理概念都因此得到新的内涵。 相似文献
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Ioannis Gkigkitzis Ioannis Haranas Samantha Kirk 《Astrophysics and Space Science》2013,346(2):553-557
In this study, we have investigated the geometrical and physical properties of stationary axisymmetric solutions. The expressions for the axial-vector and the gravitational energy and momentum densities are obtained in the context of teleparallel equivalent of general relativity. The obtained results are compared with that obtained previously in the context of Møller’s tetrad theory of gravitation. We discussed special cases of these solutions. 相似文献
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E. H. Dowdye 《Astronomische Nachrichten》2007,328(2):186-191
Intense observations of the galactic center since 1992 have revealed the presence of a supermassive object located there, some 26 000 light years from Earth. The mass of the galactic center was determined using time resolved astrometry over a time span of 13 years, from 1992 to present. The observations clearly show that the stars in the immediate vicinity of the supermassive galactic center, denoted as Sagittarius A* (Sgr A*), move along purely Keplerian orbits around Str A*. Observation of the rapidly moving stars permitted astrophysicists to determine a mass for the galactic center of around 3.6 million solar masses. Time resolved images of the Keplerian motions of these stars has exhibited to date no evidence of distortions in the images due to gravitational light bending effects, as predicted by General Relativity. In this paper, a well known tool commonly used by astrophysicists for estimating the effect of gravitation on light rays was examined. The results reveal flaws in the understanding of fundamental principles in mathematical physics applied to gravitational effects on rays of light, as predicted by General Relativity, at the site of a point‐like gravitating masses such as the galactic center mass. Application of the Gauss Law to point‐like gravitating masses shows that a requirement for the colinear alignment of the light source, the lensing and the observer is not necessary for an observation of gravitational lensing as predicted by General Relativity. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Exact solutions for the vacuum field equations of General Projective Relativity of Arcidiacono (1986) are obtained for the non-static Einstein-Rosen metric (Einstein and Rosen, 1937). The nature of singularities in these solutions is discussed. 相似文献
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Garth A. Barber 《Astrophysics and Space Science》2002,282(4):683-730
A theory is described which produces continuous creation by adapting that of Brans-Dicke. The universe is seen to be created
out of the zero point energy field by self-contained gravitational, scalar, and matter fields. The theory is conformally equivalent
to General Relativity in vacuo.Both the Jordan and the Einstein frames are physical and they conserve energy and four-momentum respectively. The conformal
equivalence has the consequence that predictions of the theory in solar system experiments are identical with General Relativity,
but definitive experiments exist which distinguish between the two theories. The cosmological solution yields a linear expansion
with a dynamical density parameter Omega of
anda cold matter density parameter of
, but the universe is closed. The theory is free of the horizon, smoothness and density problems of GR and therefore does
not need Inflation. It does however require an exotic equation of state with negative pressure and it is suggested that this
is provided by a false vacuum or zero point energy determined, and there forelimited by, its field equations thereby overcoming
the ‘lambda problem’.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Teleparallel gravity is an equivalent formulation of general relativity in which instead of the Ricci scalar R, one uses the torsion scalar T for the Lagrangian density. Recently teleparallel dark energy has been proposed by Geng et al. (in Phys. Lett. B 704, 384, 2011). They have added quintessence scalar field, allowing also a non-minimal coupling with gravity in the Lagrangian of teleparallel gravity and found that such a non-minimally coupled quintessence theory has a richer structure than the same one in the frame work of general relativity. In the present work we are interested in tachyonic teleparallel dark energy in which scalar field is responsible for dark energy in the frame work of torsion gravity. We find that such a non-minimally coupled tachyon gravity can realize the crossing of the phantom divide line for the effective equation of state. Using the numerical calculations we display such a behavior of the model explicitly. 相似文献
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Trevor W. Marshall 《Astrophysics and Space Science》2012,342(2):329-332
The contemporary notion of black hole originates in Oppenheimer and Snyder’s 1939 article “On Continued Gravitational Contraction” (Phys. Rev. 56:455, 1939). In particular, Penrose (Phys. Rev. Lett. 14:57, 1965) showed that their metric gave rise to trapped surfaces, that is regions of space from which no light rays can escape, and proved that within such surfaces black-hole formation is inevitable. Section “No trapped surfaces” of this article shows that a simple modification of the Oppenheimer-Snyder metric, fully consistent with General Relativity, may be made, so that all radial light rays originating in the interior escape to the exterior. There is no trapped surface and no black hole; on the contrary there is a stable end state with finite density, contained within a sphere of Schwarzschild radius. Implications for the interpretation of General Relativity, and also for experimental observation of supermassive objects and the Event Horizon Telescope project, are discussed in the concluding section. 相似文献
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An impact model of gravity designed to emulate Newton’s law of gravitation is applied to particles with relative motions at slow and relativistic speeds. Based on this model, a gravitational interaction mode is then conceived between photons and massive particles. This implies a deflection perpendicular to the propagation direction of a photon twice as large as expected from the mass-energy relation of photons—in accordance with observations and the General Theory of Relativity. The longitudinal interaction is compatible with the energy and momentum conservation principles applied to massless entities, and the results are consistent with the observed Shapiro delay. 相似文献