Thermodynamical properties of dark energy with the equation of state $% \omega =\omega_{0}+\omega_{1}z$

TL;DR

This paper investigates the thermodynamical properties of dark energy with a specific equation of state, analyzing the validity of thermodynamic laws on apparent and event horizons across different redshifts.

Contribution

It demonstrates that the first and second laws of thermodynamics hold on the apparent horizon but not on the event horizon, suggesting the apparent horizon as the thermodynamic boundary of the universe.

Findings

Thermodynamic laws are satisfied on the apparent horizon at all redshifts.

Thermodynamic laws break down on the event horizon at some redshifts.

The apparent horizon may serve as the thermodynamic boundary of the universe.

Abstract

The thermodynamical properties of dark energy are usually investigated with the equation of state $\omega =\omega_{0}+\omega_{1}z$. Recent observations show that our universe is accelerating, and the apparent horizon and the event horizon vary with redshift $z$. When definitions of the temperature and entropy of a black hole are used to the two horizons of the universe, we examine the thermodynamical properties of the universe which is enveloped by the apparent horizon and the event horizon respectively. We show that the first and the second laws of thermodynamics inside the apparent horizon in any redshift are satisfied, while they are broken down inside the event horizon in some redshift. Therefore, the apparent horizon for the universe may be the boundary of thermodynamical equilibrium for the universe like the event horizon for a black hole.