J. G. da Silva | Searcharxiv

arXiv2019

Gödel and Gödel-type universes in K-essence theory

In this paper, the Gödel-type solutions within the k-essence theory are investigated. The consistency of field equations, causality violation and existence of closed timelike curves are studied. The conditions for existence of Gödel and Gödel-type solutions are determined for any function that defines the k-essence. By taking different sources of matter, it is shown that this theory of gravity allows causal and non-causal Gödel-type solutions.

gr-qc↗

arXiv2017

On Gravitational Energy in Conformal Teleparallel Gravity

The paper deals with the definition of gravitational energy in conformal teleparallel gravity. The total energy is defined by means of the field equations which allow a local conservation law. Then such an expression is analyzed for a homogeneous and isotropic Universe. This model is implemented by the Friedmann-Robertson-Walker (FRW) line element. The energy of the universe in the absence of matter is identified with the dark energy, however it can be expanded for curved models defining such an energy as the difference between the total energy and the energy of the perfect fluid which is the matter field in the FRW model.

gr-qc↗