We give an example of a spacetime having an infinite thin rotating cylindrical shell constituted by a charged perfect fluid as a source. As the interior of the shell the Bonnor–Melvin universe is considered, while its exterior is represented by Datta– Raychaudhuri spacetime. We discuss the energy conditions and we show that our spacetime contains closed timelike curves. Trajectories of charged ...

We give an example of a spacetime having an infinite thin rotating cylindrical shell constituted by a charged perfect fluid as a source. As the interior of the shell the Bonnor–Melvin universe is considered, while its exterior is represented by Datta– Raychaudhuri spacetime. We discuss the energy conditions and we show that our spacetime contains closed timelike curves. Trajectories of charged ...

The first law of black hole mechanics (in the form derived by Wald), is expressed in terms of integrals over surfaces, at the horizon and spatial infinity, of a stationary, axisymmetric black hole, in a diffeomorphism invariant Lagrangian theory of gravity. The original statement of the first law given by Bardeen, Carter and Hawking for an Einstein-perfect fluid system contained, in addition, v...

In this article the method of conformal transformation is used to generate perfect fluid solutions of Einstein’s equations from vacuum spacetimes. The conditions on the conformal factor in order to generate a perfect fluid spacetime are presented. With Minkowski as a seed spacetime, these conditions are applied and a particular solution is found. It belongs to the family of Stephani spacetimes ...

In the present paper, we carried out a systematic investigation of pseudo-quasi-conformal curvature tensor has been made on four-dimensional spacetime general relativity. The fulfilling Einstein?s field equations with vanishing is being considered and existence Killing conformal vectors such have established. At last, extend similar case for cosmological models dust perfect fluid spacetime.

The present paper aims to deliberate the geometric composition of a perfect fluid spacetime with torse-forming vector field ? in connection conformal Ricci–Yamabe metric and ?-Ricci–Yamabe metric. We delineate conditions for soliton be expanding, steady or shrinking. also discuss on some special types such as dust fluid, dark radiation era. Furthermore, we design find its characteristics lastly...

We study the consequences of timelike and spaccelike conformal Ricci and conformal matter collineations for anisotropic fluid in the context of General Relativity. Necessary and sufficient conditions are derived for a spacetime with anisotropic fluid to admit conformal Ricci and conformal matter collineations parallel to u and x. These conditions for timelike and spacelike conformal Ricci and c...

When solving the equations of General Relativity in a symmetric sector, it is natural to consider the same symmetry for the geometry and stress-energy. This implies that for static and isotropic spacetimes, the most general natural stress-energy tensor is a sum of a perfect fluid and a radial imperfect fluid component. In the special situations where the perfect fluid component vanishes or is a...

We assume that our universe originated from highly excited and interacting strings with coupling constant gs = O(1). Fluctuations of spacetime geometry are large in such strings and the physics dictating the emergence of a final spacetime configuration is not known. We propose that, nevertheless, it is determined by an entropic principle that the final spacetime configuration must have maximum ...

Einstein’s field equations with variable gravitational and cosmological “constant” are considered in presence of perfect fluid for Bianchi type-I spacetime. Consequences of the four cases of the phenomenological decay of Λ have been discussed which are consistent with observations. The physical significance of the cosmological models have also been discussed. PACS: 98.80.Es, 98.80.-k