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G\"{o}del-type universes in Palatini f(R) gravity by Santos, J.; Reboucas, M. J.; Oliveira, T. B. R. F. is a scholarly article available to read on EtoBox.

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We examine the question as to whether the Palatini f(R) gravity theories permit space-times in which the causality is violated. We show that every perfect-fluid G\"{o}del-type solution of Palatini f(R) gravity with density $\rho$ and pressure $p$ that satisfy the weak energy condition $\rho+p \geq 0$ is necessarily isometric to the G\"odel geometry, demonstrating therefore that these theories present causal anomalies in the form of closed time-like curves. This result extends a theorem on G\"{o}del-type models to the framework of Palatini f(R) gravity theory. We concretely examine the G\"odel-type perfect-fluid solutions in specific $f(R) = R - \alpha/R^{n}$ Palatini gravity theory, where the free parameters $\alpha$ and $n$ have been recently constrained by a diverse set of observational data. We show that for positive matter density and for $\alpha$ and $n$ within the interval permitted by the observational data, this theory does not admit the G\"odel geometry as a perfect-fluid solution of its field equations. In this sense, this theory remedies the causal pathology in the form of closed time-like curves which is allowed in general relativity. We derive an expression for a criti

Author

Santos, J.; Reboucas, M. J.; Oliveira, T. B. R. F.

Published

2010

Language

EN