The generalized second law of thermodynamics in generalized gravity theories

Abstract

We investigate the generalized second law of thermodynamics (GSL) in generalized theories of gravity. We examine the total entropy evolution with time including the horizon entropy, the non-equilibrium entropy production, and the entropy of all matter, field and energy components. We derive a universal condition to protect the generalized second law and study its validity in different gravity theories. In Einstein gravity, (even in the phantom-dominated universe with a Schwarzschild black hole), Lovelock gravity, and braneworld gravity, we show that the condition to keep the GSL can always be satisfied. In $f(R)$ gravity and scalar-tensor gravity, the condition to protect the GSL can also hold because the gravity is always attractive and the effective Newton constant should be approximate constant satisfying the experimental bounds.

19 pages, no figure, mistakes corrected, references added, to appear in Class. Quantum Grav

References in corpus (6)

• A Note on Thermodynamics of Black Holes in Lovelock Gravity
• Thermodynamical Properties of Apparent Horizon in Warped DGP Braneworld
• Friedmann Equations and Thermodynamics of Apparent Horizons
• Deep Connection Between Thermodynamics and Gravity in Gauss-Bonnet Braneworld
• Generalized second law in modified theory of gravity
• Schwarzschild black hole and the generalized second law in phantom-dominated universe

Cited by in corpus (4)

• Hawking Radiation of Apparent Horizon in a FRW Universe
• Corrected Entropy-Area Relation and Modified Friedmann Equations
• Thermodynamics in $F(R)$ gravity with phantom crossing
• Generalized Second Law of Thermodynamics in Extended Theories of Gravity