Does the entropy of the Universe tend to a maximum?

TL;DR

This paper explores whether the universe's entropy tends to a maximum, suggesting that, based on the Hubble expansion, the universe likely behaves as an ordinary system with entropy approaching a finite limit.

Contribution

It proposes a hypothesis that the universe's entropy may reach a maximum, contrasting with gravity-dominated systems where entropy could increase indefinitely.

Findings

Universe's entropy likely tends to a maximum

Based on Hubble expansion history, universe behaves as an ordinary system

Contrasts with black hole formation scenarios

Abstract

Ordinary, macroscopic systems, naturally tend to a state of maximum entropy compatible with their constraints. However, this might not hold for gravity-dominated systems since their entropy may increase without bound unless this is precluded by the formation of a black hole. In this short note we suggest, based on the Hubble expansion history, that our Universe likely behaves as an ordinary system, i.e., that its entropy seems to tend to some maximum value.