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82.
Despite a century-long effort, a proper energy-stress tensor of the gravitational field, could not have been discovered. Furthermore, it has been discovered recently that the standard formulation of the energy-stress tensor of matter, suffers from various inconsistencies and paradoxes, concluding that the tensor is not consistent with the geometric formulation of gravitation [Astrophys. Space Sci., 2009, 321: 151; Astrophys. Space Sei., 2012, 340: 373]. This perhaps hints that a consistent theory of gravitation should not have any bearing on the energy-stress tensor. It is shown here that the so-called "vacuum" field equations Rik = 0 do not represent an empty spacetime, and the energy, momenta and angular momenta of the gravitational and the matter fields are revealed through the geometry, without including any formulation thereof in the field equations. Though, this novel discovery appears baffling and orthogonal to the usual understanding, is consistent with the observations at all scales, without requiring the Moreover, the resulting theory circumvents the besides explaining some unexplained puzzles. hypothetical dark matter, dark energy or inflation long-standing problems of the standard cosmology 相似文献
83.
In this paper we present higher dimensional cosmological model of the universe with the decaying vacuum energy density in
the realm of model with a time varying gravitational constant. We have shown that our model admits the usual higher dimensional
de Sitter solution and the other solutions characterized by the constant ratio between matter density and the total energy
density. Our work is the generalization of the work obtained earlier by Carneiro (Proceedings of the MG10 Meeting held at
Brazilian Center for Research in Physics (CBPF), Rio de Janeiro, Brazil, 20–26 July, 2003) in four dimensional space-time. 相似文献
84.
The universe content is considered as a non-perfect fluid with bulk viscosity and can be described by a general equation of state (endowed some deviation from the conventionally assumed cosmic perfect fluid model). An explicitly bulk viscosity dark energy model is proposed to confront consistently with the current observational data sets by statistical analysis and is shown consistent with (not deviated away much from) the concordant A Cold Dark Matter (CDM) model by comparing the decelerating parameter. Also we compare our relatively simple viscosity dark energy model with a more complicated one by contrast with the concordant ACDM model and find our model improves for the viscosity dark energy model building. Finally we discuss the perspectives of dark energy probes for the coming years with observations. 相似文献
85.
86.
Classical Solar System tests of photons coupled to Weyl tensor with two polarizations were studied in a recent work. A coupling strength parameter α in this model was firstly obtained as |α|<4×1011 m2 by using available datasets in the Solar System. In this paper, a new test called by gravitational time advancement is proposed and investigated to test such the coupling. This new test, which is quite different from Shapiro time delay, depends strongly on round-trip proper time span (not coordinate time one) of flight of radio pulses between an observer on the Earth and a distant spacecraft. For ranging a spacecraft getting far away from the Sun, two special cases (the superior/inferior conjunctions) are used to analyse the observability in the advancement contributed by the Weyl coupling. We found that the situation of the inferior conjunction is more suitable for detecting the advancement caused by such the Weyl coupling. In either case, two kinds of polarizations make the advancement in the model smaller or larger than the one of general relativity. Although the observability in the advancement could be out of the reach of already existing technology, the implement of planetary laser ranging and optical clocks might provide us more insights on such the Weyl coupling in the near future. 相似文献
87.
Gravitational contributions to the running of gauge couplings arecalculated by using different regularization schemes. As the β function concerns counter-terms of dimension four, only quadratic divergences from the gravitational contributions need to be investigated. A consistent result is obtained by using a symmetry-preserving loop regularization with string-mode regulators which can appropriately treat the quadratic divergences andpreserve non-abelian gauge symmetry. The harmonic gauge conditionfor gravity is used in both diagrammatical and background field calculations, the resulting gravitational corrections to the β function are found to be nonzero, which is different from previous results presented in the existing literatures. 相似文献
88.
One novel polyoxometalate compound connected via trivalent cerium cation as bridge H2{[K(H2O)2]2[Ce(H2O)5]2(H2Mo1.16W10.84O42)}·8H2O 1 was designed and synthesized in aqueous solution. X-ray diffraction analysis reveals that the structure of 1 is a three-dimensional framework assembled from the arrangement of H2Mo1.16W10.84O42 (named paradodecmetalate-B) and Ce(H2O)53 containing two planes, which are constructed through the unification of H2Mo1.16W10.84O4210- and Ce(H2O)53 along the [100] and [001] directions. Crystal data: H96Ce4K4Mo2.32O128W21.68, Mr = 7074.89, monoclinic, P21/n, a = 12.5037(17), b = 17.002(2), c = 12.7473(17) (A), β = 105.966(2)°, V = 2605.4(6) (A)3, Z = 1, Dc = 4.509 g/cm3, F(000) = 3132, μ = 26.098 mm(1, R = 0.0377 and wR = 0.0789 (I > 2σ(I)). 相似文献
89.
90.
人造地球卫星与月亮在地心参考系中的受力分析 总被引:2,自引:3,他引:2
指出在全面分析被研究对象所受的力时,必须同时分析参照物所受的力,否则便漏掉了惯性力;地心参考系可以充当惯性系的空间范围是有限的. 相似文献