Interacting Three Fluid System and Thermodynamics of the Universe Bounded by the Event Horizon

TL;DR

This paper investigates the thermodynamics of a universe with three interacting fluids—dark energy, dark matter, and radiation—bounded by the event horizon, analyzing entropy variations and the validity of the generalized second law.

Contribution

It introduces a model of universe thermodynamics considering three interacting fluids and examines entropy changes and the generalized second law at the event horizon.

Findings

Entropy variation of the horizon is derived from the unified first law.

Matter entropy variation is calculated using Gibbs' law.

The generalized second law of thermodynamics is found to be valid under certain conditions.

Abstract

The work deals with the thermodynamics of the universe bounded by the event horizon. The matter in the universe has three constituents namely dark energy, dark matter and radiation in nature and interaction between then is assumed. The variation of entropy of the surface of the horizon is obtained from unified first law while matter entropy variation is calculated from the Gibbss' law. Finally, validity of the generalized second law of thermodynamics is examined and conclusions are written point wise.