Thermodynamics and Lemaitre-Tolman-Bondi void models

TL;DR

This paper investigates whether inhomogeneous Lemaitre-Tolman-Bondi void models can be thermodynamically justified, finding that Weyl curvature entropy shows promising behavior despite issues with apparent horizon entropy.

Contribution

It introduces the concept of using Weyl curvature entropy to assess the thermodynamic viability of inhomogeneous cosmological models.

Findings

Apparent horizon entropy is not thermodynamically well-behaved.

Weyl curvature entropy exhibits satisfactory thermodynamic behavior.

Weyl curvature entropy could be a useful criterion for evaluating inhomogeneous cosmologies.

Abstract

It has been argued in the literature that in order to make a matter dominated Friedmann-Lemaitre-Robertson-Walker universe compatible with the generalized second law of thermodynamics, one must invoke dark energy, or modified gravity. In the present article we investigate if in a similar spirit, inhomogeneous cosmological models can be motivated on thermodynamic grounds. We examine a particular minimal void Lemaitre-Tolman-Bondi inhomogeneous model which agrees well with observations. While on the one hand we find that the entropy associated with the apparent horizon is not well-behaved thermodynamically, on the other hand the canonical Weyl curvature entropy shows satisfactory thermodynamic behavior. We suggest that evolution of canonical Weyl curvature entropy might be a useful way to evaluate the thermodynamic viability of inhomogeneous cosmologies.