Thermodynamics in Kaluza-Klein Universe

TL;DR

This paper examines the validity of thermodynamic laws in a Kaluza-Klein universe with dark energy models, confirming their validity on the apparent horizon but not on a fixed-radius horizon for certain parameters.

Contribution

It analyzes the thermodynamic laws in Kaluza-Klein universe with generalized holographic and Ricci dark energy models, highlighting conditions for their validity.

Findings

Thermodynamic laws hold on the apparent horizon for both models.

Laws do not hold on fixed-radius horizons for certain parameters.

First and second laws are validated in specific conditions.

Abstract

This paper is devoted to check the validity of laws of thermodynamics for Kaluza-Klein universe in the state of thermal equilibrium, composed of dark matter and dark energy. The generalized holographic dark energy and generalized Ricci dark energy models are considered here. It is proved that the first and generalized second law of thermodynamics are valid on the apparent horizon for both of these models. Further, we take a horizon of radius $L$ with modified holographic or Ricci dark energy. We conclude that these models do not obey the first and generalized second law of thermodynamics on the horizon of fixed radius $L$ for a specific range of model parameters.