共查询到20条相似文献,搜索用时 15 毫秒
1.
We study the curvature tensors and field equations in then-dimensional SE manifold SEXn. We obtain several basic properties of the vectorsS
andU
and then of the SE curvature tensor and its contractions, such as a generalized Ricci identity, a generalized Bianchi identity, and two variations of the Bianchi identity satisfied by the SE Einstein tensor. Finally, a system of field equations is discussed in SEXn and one of its particular solutions is constructed and displayed. 相似文献
2.
A homogeneous Bianchi type VIh cosmological model filled with perfect fluid, null electromagnetic field and streaming neutrinos is obtained for which the free gravitational field is of the electric type. The barotropic equation of statep = (–1) is imposed in the particular case of Bianchi VI0 string models. Various physical and kinematical properties of the models are discussed. 相似文献
3.
M. W. Evans 《Foundations of Physics Letters》1996,9(4):397-405
The equations of free-space electrodynamics are derived directly from the Riemann curvature tensor and the Bianchi identity of general relativity by contracting on two indices to give a novel antisymmetric Ricci tensor. Within a factore/h, this is the field-strength tensor G of free-space electrodynamics. The Bianchi identity for G describes free-space electrodynamics in a manner analogous to, but more general than, Maxwell's equations for electrodynamics, the critical difference being the existence in general and special relativity of the Evans-Vigier fieldB
(3). 相似文献
4.
Pantelis S. Apostolopoulos 《General Relativity and Gravitation》2004,36(8):1939-1945
We show that the tilted perfect fluid Bianchi VI0 family of self-similar models found by Rosquist and Jantzen [K. Rosquist and R. T. Jantzen, Exact power law solutions of the Einstein equations, 1985 Phys. Lett. 107A 29–32] is the most general class of tilted self-similar models but the state parameter lies in the interval (6/5, 3/2). The model has a four dimensional stable manifold indicating the possibility that it may be future attractor, at least for the subclass of tilted Bianchi VI0 models satisfying n
=0 in which it belongs. In addition the angle of tilt is asymptotically significant at late times suggesting that for the above subclasses of models the tilt is asymptotically extreme. 相似文献
5.
S. Brian Edgar 《General Relativity and Gravitation》1995,27(2):223-231
When the Bianchi equation and the wave equation for the Weyl spinor are written in the form which they take for Einstein spaces, but with the symmetric 4-spinor
ABCD
considered arbitrary and with the background space unspecified,
EA
EBCD=0; (+12)
ABCD
–6(AB
EF
(
CD
)EF =0 it is shown that — in general — for this pair of equations to be consistent, the background space has to be an Einstein space, and the symmetric 4-spinor
ABCD
has to be the Weyl spinor of this space. 相似文献
6.
A method for obtaining anisotropic, rotationless viscous fluid matter solutions of Bianchi type I and Segré type [1, 111] with the barotropic equation of state is presented. Solutions for which the anisotropy decreases exponentially or with a power law as well as solutions with average Hubble parameterH t
–1 are discussed. Also, a class of solutions with constant anisotropy and Bianchi type VIh is found. The dominant energy condition holds and the transport coefficients show the right sign. 相似文献
7.
The field equations following from a LagrangianL(1/L)(–g)1/2[(1/2)R+l
2(R
lk
R
lk
+R
2)] will be considered for Bianchi type-I homogeneous models. Thereby the special case,+3=0, is considered qualitatively for axially symmetric anisotropic metrics. Generically, the solutions have both past and future singularities, but it will be proven by topological arguments that the two-dimensional space of solutions possesses a one-parameter subspace of solutions with a behavior similar to the Kasner solution. 相似文献
8.
J. H. Chilton K. S. Hammon L. K. Norris 《International Journal of Theoretical Physics》1993,32(11):2059-2076
The Bianchi identities for theP(4)=O(1, 3) 4* theory of gravitation and electromagnetism are decomposed into the standardO(1, 3) Riemannian Bianchi identity plus an additional 4* component. When combined with the Einstein-Maxwell affine field equations the 4* components of theP(4) Bianchi identities imply conservation of magnetic charge and the wave equation for the Maxwell field strength tensor. These results are analyzed in light of the special geometrical postulates of theP(4) theory. We show that our development is the analog of the manner in which the Riemannian Bianchi identities, when combined with Einstein's field equations, imply conservation of stress-energy-momentum and the wave equation for the LanczosH-tensor. 相似文献
9.
A theory is considered for a free scalar field with a conformal connection in a curved space-time with a Bianchi type-I metric. A representation is obtained for the Green's functionGin<0¦T(x)(x)¦0>
in in the form of an integral of a Schwinger-DeWitt kernel along a contour in a plane of complex-valued proper time. It is shown how a transition may be accomplished from Green's functions in space with the Euclidean signature to Green's functions in space with Minkowski signature and vice versa.Translated from Izvestiya Vyssnikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 20–27, June, 1988. 相似文献
10.
11.
G. Lessner 《International Journal of Theoretical Physics》1977,16(2):99-110
An approximation method is developed to calculate the gravitational field of a matter sourceT
moving on a curved background metric that is an exact solution of the field equations and deviates only weakly from flat space-time. The fieldh
of the sourceT
is supposed to be much smaller than the curved part of the background, so that in the series expansion ofh
each order can be expanded in powers of the background. 相似文献
12.
In modified generalized scalar-tensor (GST) theory, the cosmological term Λ is a function of the scalar field ϕ and its derivatives . We obtain exact solutions of the field equations in Bianchi Type-I, V and VIo space-times. The evolution of the scale factor,
the scalar field and the cosmological term has been discussed. The Bianchi Type-I model has been discussed in detail. Further,
Bianchi Type-V and VIo models can be studied on the lines similar to Bianchi Type-I model.
相似文献
13.
The evolution of a class of exact spatially homogeneous cosmological models of Bianchi type VI
h
is discussed. It is known that solutions of type VI
h
cannot approach isotropy asymptotically at large times. Indeed the present class of solutions become asymptotic to an anisotropic vacuum plane wave solution. Nevertheless, for these solutions the initial anisotropy can decay, leading to a stage of finite duration in which the model is close to isotropy. Depending on the choice of parameters in the solution, this quasi-isotropic stage can commence at the initial singularity, in which case the singularity is of the type known as isotropic or Friedmann-like. The existence of this quasi-isotropic stage implies that these models can be compatible in principle with the observed universe. 相似文献
14.
Haydeh Sirousse Zia 《General Relativity and Gravitation》1994,26(6):587-597
By using the [General Relativity + additional matter fields] formulation (which depends on a redefined metrich
) of metric theories of gravitation, the study of singularities characterized by incomplete nonspacelike geodesics is simplified, but may be used only if (at least) the non-spacelike geodesics of the original metricg
are conserved under the transformation betweeng
and the new metrich
. In order that every class of geodesies of a diagonal Bianchi I metric correspond to the same class of geodesies of a diagonal metrich
, it is necessary that the transformation between these two metrics be a constant (positive) conformal transformation. We analyse the implications of the previous results for the singularitiesg
when the latter is a solution of theories with a quadratic or polynomial Lagrangian. 相似文献
15.
We find exact solutions to the Wheeler-DeWitt equation, for a certain factor ordering. They have the form =We
± for class A Bianchi models, where is a solution to the classical Hamilton-Jacobi equation, generalizing the only known solution of Moncrief and Ryan for the Bianchi type IX model in standard quantum cosmology. The same kind of solution has also been found in supersymmetric quantum cosmology. 相似文献
16.
Enrique Guzmán 《General Relativity and Gravitation》1991,23(9):1007-1010
In this paper we have obtained the general vacuum solution for Bianchi type V in the Brans-Dicke theory. It is shown that for the special case=0, the sourceless scalar field is dynamically an essential factor which determines the cosmological expansion parametersR
i
and the singularity does not occur whent=0. For this solution there is no antigravity (>0), which disagrees with other solutionsa for BDT-Bianchi type V 相似文献
17.
The paper presents some exact solutions of Bianchi types I and III and Kantowski-Sachs cosmological models consisting of a dissipative fluid along with an axial magnetic field. A barytropic equation of state (p=), together with a pair of linear relations between the matter density (), the shear scalar (), and the expansion scalar () have been assumed for simplicity. The solutions are basically of two different types, one for the Bianchi I and the other for III and Kantowski-Sachs type. The presence of the magnetic field, however, does not change the fundamental nature of the initial singularity. 相似文献
18.
C. B. G. McIntosh M. S. Hickman A. W. -C. Lun 《General Relativity and Gravitation》1988,20(7):647-657
One of the problems in dealing with double (and single) Kerr-Schild metrics is that there is a good deal of combined coordinate and tetrad freedom in writing any particular metric of this type in a standard form, and this freedom is not yet properly understood. This paper investigates part of this problem by examining the freedom in choosing the background flat metric for the standard form of a vacuum IDKS (integrable double Kerr-Schild) metric and by looking at the freedom in choosing the potentialH, which determines IDKS flat metrics in this standard form. Examples are given of different forms ofH which generate flat space. A slight generalization of the vacuum IDKS metric is also given in which thesurface equations andcurvature scalar are zero (i.e.,
00=
01=
11==0 in Newman-Penrose language) but the othercentral equations and theresidual equations are nonzero. 相似文献
19.
We use numerical integrations to study the asymptotical behaviour of a homogeneous but anisotropic Bianchi type IX model in General Relativity with a massive scalar field. As it is well known, for a Brans-Dicke theory, the asymptotical behaviour of the metric functions is ruled only by the Brans-Dicke coupling constant 0 with respect to the value –3/2. In this paper we examine if such a condition still exists with a massive scalar field. We also show that, contrary to what occurs for a massless scalar field, the singularity oscillatory approach may exist in the presence of a massive scalar field having a positive energy density. 相似文献
20.
Christian Heinicke 《General Relativity and Gravitation》2001,33(6):1115-1130
We motivate the definition of the Einstein 3-form G
by means of the contracted 2nd Bianchi identity. This definition contains the whole curvature 2-form. The L
1-form, defined via G
= L
*( ) ( is the Hodge-star, the coframe), is equivalent to the Einstein 3-form and contains all the information of the curvature 2-form relevant for the definition of the Einstein 3-form. A variational formula of Salgado on quadratic invariants of the L
1-form is discussed, generalized, and put into proper perspective. 相似文献