Entropy and anisotropy

TL;DR

This paper explores the concept of entropy in anisotropic cosmological models, analyzing thermodynamic laws and the Cardy-Verlinde entropy construction, highlighting differences and limitations in their applicability.

Contribution

It introduces a detailed analysis of entropy definitions in Bianchi I and V models and compares thermodynamic and Cardy-Verlinde approaches, revealing their incompatibility.

Findings

Thermodynamic entropy for anisotropic models is derived from standard laws.

Cardy-Verlinde entropy cannot be directly associated with thermodynamic entropy in these models.

The study highlights limitations of the Cardy-Verlinde construction in anisotropic cosmologies.

Abstract

We address the problem of defining the concept of entropy for anisotropic cosmological models. In particular, we analyze for the Bianchi I and V models the entropy which follows from postulating the validity of the laws of standard thermodynamics in cosmology. Moreover, we analyze the Cardy-Verlinde construction of entropy and show that it cannot be associated with the one following from relativistic thermodynamics.