Entropy of the FRW cosmology based on the brick wall method

TL;DR

This paper applies the brick wall method to FRW cosmology to compute and bound the statistical entropy, finding the vacuum energy-dominated era yields maximal entropy consistent with covariant bounds.

Contribution

It extends the brick wall method from black hole entropy to cosmology, establishing entropy bounds in different eras of the universe.

Findings

The entropy in FRW cosmology can be bounded using a covariant cutoff.

The vacuum energy-dominated era has the highest entropy among cosmological eras.

The entropy bound aligns with the covariant entropy bound in cosmological settings.

Abstract

The brick wall method in calculations of the entropy of black holes can be applied to the FRW cosmology in order to study the statistical entropy. An appropriate cutoff satisfying the covariant entropy bound can be chosen so that the entropy has a definite bound. Among the entropy for each of cosmological eras, the vacuum energy-dominated era turns out to give the maximal entropy which is in fact compatible with assumptions from the brick wall method.