首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   10篇
  免费   0篇
物理学   10篇
  1999年   3篇
  1998年   3篇
  1997年   4篇
排序方式: 共有10条查询结果,搜索用时 15 毫秒
1
1.
The solutions of two-dimensional gravityfollowing from a non-linear Lagrangian =f(R)g are classified, and their symmetry andsingularity properties are described. Then a conformaltransformation is applied to rewrite these solutions as analogoussolutions of two-dimensional Einstein-dilaton gravityand vice versa.  相似文献   
2.
We prove that for non-linear L = L(R), G = dL/dR 0 the Lagrangians L and ^L(^R) with ^L = 2R/G3 - 3L/G4, ^gij = G2 gij and ^R = 3R/G2 - 4L/G3 give conformally equivalent fourth-order field equations being dual to each other. The proof represents a new application of the fact that the operator - R/6 is conformally invariant.  相似文献   
3.
We show that a relativistic gas may be at"global" equilibrium in the expanding universe for anyequation of state 0 < p /3, provided thatthe gas particles move under the influence of aself-interacting, efiective one-particle force in between elasticbinary collisions. In the force-free limit we recoverthe equilibrium conditions for ultrarelativistic matterwhich imply the existence of a conformal timelike Killing vector.  相似文献   
4.
In this paper we study the consequences of the existence of conformal and special conformal Killing vectors (CKV, SCKV) for string cloud and string fluid in the context of general relativity. The inheritance symmetries of the string cloud and string fluid are discussed. Einstein's field equations have been solved for static spherically symmetric space-time with cloud and fluid of strings source via CKV.  相似文献   
5.
Those space-times admitting special conformal vector fields and those admitting special projective vector fields have recently been studied. In this paper these two classes of space times are shown to be very closely related to each other. Certain uniqueness features of (and necessary extra symmetries contained in) the associated Lie algebras are discussed and the dimensionality of each of the algebras is computed.  相似文献   
6.
It is well-known that any scalar can be promoted to a Jordan-Brans-Dicke type scalar coupling to the Einstein-Hilbert term through a field dependent Weyl transformation of the metric. The Weyl rescaling also transforms mass terms into coupling constants between matter and the scalar. It is pointed out that there exists a distinguished metric where all scalars decouple from an arbitrary fiducial fermion, e.g. the nucleon. If bound states of this fermion are used to define distances and to probe the interior of the forward light cone, it seems reasonable to say that the metric in that particular frame defines the local geometry of space-time at low energies, as probed by experimental gravity and cosmology.  相似文献   
7.
The motivation for this paper is the recent interest in the study of symme tries in general relativity and its purpose is to discuss the mathematical foundations required for such a study. The general (formal and informal) ideas of what constitutes a symmetry of space-time are discussed and developed and the idea of a Lie algebra of symmetry vector fields is studied in detail. The relationship between such Lie algebras and the ideas of Lie transformation group theory (Palais' theorems) is stated and a general theorem regarding the orbits of such symmetries is given. Finally some specific symmetries in general relativity are explored and some of their similarities and differences noted.  相似文献   
8.
9.
Using Penrose diagrams the causal structure ofthe static spherically symmetric vacuum solution toconformal (Weyl) gravity is investigated. A strikingaspect of the solution is an unexpected physicalsingularity at r = 0 caused by a linear term in the metric.We explain how to calculate the deflection of light incoordinates where the metric is manifestly conformal toflat i.e. in coordinates where light movesin straight lines.  相似文献   
10.
The general solution for non-rotating perfect-fluid spacetimes admitting one Killing vector and two conformal (non-isometric) Killing vectors spanning an abelian three-dimensional conformal algebra (C3) acting on spacelike hypersurfaces is presented. It is of Petrov type D; some properties of the family such as matter contents are given. This family turns out to be an extension of a solution recently given in [9] using completely different methods. The family contains Friedman-Lemaître-Robertson-Walker particular cases and could be useful as a test for the different FLRW perturbation schemes. There are two very interesting limiting cases, one with a non-abelian G2 and another with an abelian G2 acting non-orthogonally transitively on spacelike surfaces and with the fluid velocity non-orthogonal to the group orbits. No examples are known to the authors in these classes.  相似文献   
1
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号