Godel and Godel-type solutions in the Palatini f(R,T) gravity theory

The Palatini f(R,T) gravity theory is considered. The standard Einstein-Hilbert action is replaced by an arbitrary function of the Ricci scalar R and of the trace T of the energy-momentum tensor. In the Palatini approach, the Ricci scalar is a function of the metric and the connection. These two quantities, metric and connection, are taken as independent variables. Then, it is examined whether Palatini f(R,T) gravity theory allows solutions in which lead to violation of causality. The Godel and Godel-type spacetimes are considered. In addition, a critical radius, which permits to examine limits for violation of causality, is calculated. It is shown that, for different matter contents, noncausal solutions can be avoided in this Palatini gravitational theory.

Automated summary

The Palatini f(R,T) gravity theory allows for the replacement of the standard Einstein-Hilbert action with an arbitrary function of the Ricci scalar R and the trace T of the energy-momentum tensor, where the metric and connection are treated as independent variables, avoiding the occurrence of noncausal solutions.