Thermodynamics in Loop Quantum Cosmology

TL;DR

This paper explores the thermodynamics of the universe within loop quantum cosmology, showing that the effective density and pressure act as thermodynamic quantities and that classical thermodynamic laws hold in this quantum gravity framework.

Contribution

It demonstrates that the thermodynamic description remains valid in LQC and identifies effective density and pressure as thermodynamic variables in the semiclassical regime.

Findings

Effective density and pressure serve as thermodynamic quantities.

Thermodynamic laws are consistent within LQC.

Equilibrium thermodynamics remains valid in the LQC framework.

Abstract

Loop quantum cosmology (LQC) is very powerful to deal with the behavior of early universe. And the effective loop quantum cosmology gives a successful description of the universe in the semiclassical region. We consider the apparent horizon of the Friedmann-Robertson-Walker universe as a thermodynamical system and investigate the thermodynamics of LQC in the semiclassical region. The effective density and effective pressure in the modified Friedmann equation from LQC not only determine the evolution of the universe in LQC scenario but are actually also found to be the thermodynamic quantities. This result comes from the energy definition in cosmology (the Misner-Sharp gravitational energy) and is consistent with thermodynamic laws. We prove that within the framework of loop quantum cosmology, the elementary equation of equilibrium thermodynamics is still valid.