Cosmological entropy and generalized second law of thermodynamics in $F(R,G)$ theory of gravity

TL;DR

This paper investigates the validity of the second law and generalized second law of thermodynamics at the apparent horizon in $F(R,G)$ gravity, analyzing conditions for thermodynamic consistency in specific cosmological models.

Contribution

It derives conditions for the second law to hold in $F(R,G)$ gravity and applies them to quasi-de Sitter and power-law expanding universes.

Findings

Conditions for thermodynamic laws in $F(R,G)$ gravity are established.

Thermodynamic laws are shown to hold under specific conditions in the models considered.

The study links modified gravity theories with thermodynamic principles in cosmology.

Abstract

We consider a spatially flat Friedmann-Lemaitre-Robertson-Walker space time and investigate the second law and the generalized second law of thermodynamics for apparent horizon in generalized modified Gauss Bonnet theory of gravity (whose action contains a general function of Gauss Bonnet invariant and the Ricci scalar: $F(R,G)$). By assuming that the apparent horizon is in thermal equilibrium with the matter inside it, conditions which must be satisfied by $F(R,G)$ are derived and elucidated through two examples: a quasi-de Sitter space-time and a universe with power law expansion.