Thermodynamics of the universe bounded by the cosmological event horizon and dominated by the tachyon fluid

TL;DR

This paper explores the thermodynamic behavior of a universe with a cosmological event horizon dominated by tachyon fluid, demonstrating the validity of thermodynamic laws and their relation to cosmic evolution.

Contribution

It introduces two evolution laws for such a universe and shows the first and generalized second laws hold, revealing their independence from tachyon fluid parameters.

Findings

Both thermodynamic laws are satisfied in the models.

Thermodynamic equilibrium properties differ between cases.

Thermodynamics provides insight into universe's dynamic evolution.

Abstract

Our aim is to investigate the thermodynamic properties of the universe bounded by the cosmological event horizon and dominated by the tachyon fluid. We give two different laws of evolution of our universe. Further, we show the first law and the generalized second law of thermodynamics (GSLT) are both satisfied in two cases, but their properties of the thermodynamic equilibrium are totally different. Besides, under our solutions, we find the validity of the laws of thermodynamics is irrelevant with the parameters of the tachyon fluid. Finally, we conclude that the universe bounded by the cosmological event horizon and dominated by the tachyon fluid has a good thermodynamic description. In turn, the thermodynamic description can provide a good physical interpretation for the dynamic evolution of our universe due to the equivalence between the first law of thermodynamics and the Friedmann equation to some extent.