A study on causality in f(R,φ,X) theory
Abstract
The k-essence modified f(R) gravity model, i.e., f(R,φ,X) theory is studied. The question of violation of causality, in the framework of G\"odel-type universes, is investigated in this gravitational model. Causal and non-causal solutions are allowed. A critical radius for non-causal solution is calculated. It is shown that the violation of causality depends on the content of matter.
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