Gödel universe in f(R,T) gravity

In this study, we have considered Gödel universe in the context of [Formula: see text] modified theory of gravity, where the gravitational Lagrangian is given by an arbitrary function of the Ricci scalar [Formula: see text] and the trace of the energy–momentum tensor [Formula: see text]. We have shown that the Gödel solution exists in this modified theory for more general functional form of [Formula: see text] function than it appears in the literature.

INFLUENCIA DEL CAMPO GRAVITATORIO EXTERNO DEL UNIVERSO DE GÖDEL SOBRE EL ESPECTRO ENERGÉTICO DE PARTÍCULAS ESCALARES

INFLUENCIA DEL CAMPO GRAVITATORIO EXTERNO DEL UNIVERSO DE GÖDEL SOBRE EL ESPECTRO ENERGÉTICO DE PARTÍCULAS ESCALARES Aníbal Páuyac Huamán DOI: https://doi.org/10.33017/RevECIPeru2004.0005/ RESUMEN En el campo gravitatorio externo del universo de Gödel con simetría cilíndrica se hallan soluciones exactas de la ecuación del campo escalar y el espectro energético de las partículas escalares correspondientes. Se analizan dos casos. En el primero, las partículas se encuentran bajo la acción solamente del campo gravitatorio externo. En el otro, las partículas interactúan con un campo electromagnético externo, el cual a su vez está dentro del campo gravitatorio externo del universo de Gödel. La solución de la ecuación del campo escalar se expresa mediante los polinomios de Jacobi. El espectro energético de las partículas escalares resulta discreto debido a la rotación del universo. Palabras clave: gravitación, universo de Gödel, espectro energético, campo escalar, campo electromagnético. ABSTRACT In the external gravitational field of the Gödel universe with cylindrical symmetry, exact solutions of the scalar field equation and energy spectrum of the corresponding scalar particles are obtained. First, we considered the scalar particles only in an external gravitational field of the Gödel universe. Then, we considered the particles interacting with an external electromagnetic field, which is at the same time in the external gravitational field of the Gödel universe. The solution of the scalar field equation is obtained in the form of Jacobi polynomials. The energy spectrum of scalar particles proves to be discrete, due to rotation of the universe. Keywords: gravitation, Gödel universe, energy spectrum, scalar field, electromagnetic field.

On causality violation in Lyra Geometry

In this paper, the causality issues are discussed in a non-Riemannian geometry, called Lyra geometry. It is a non-Riemannian geometry originated from Weyl geometry. In order to compare this geometry with the Riemannian geometry, the Einstein field equations are considered. It is verified that the Gödel and Gödel-type metric are consistent with this non-Riemannian geometry. A non-trivial solution for Gödel universe in the absence of matter sources is determined without analogue in general relativity. Different sources are considered and then different conditions for causal and non-causal solutions are discussed.

GÖDEL SOLUTION IN f(R, T) GRAVITY

In this paper, we study Gödel universe in the framework of f(R, T) modified theories of gravity, where R is the curvature scalar and T the trace of the energy–momentum tensor. We demonstrate that Gödel solution occurs in this modified theory and still we suggest a path to understanding the smallness of the cosmological constant.