Horizon thermodynamics and composite metrics

TL;DR

This paper explores how gravity's thermodynamic properties can be understood through emergent scenarios where the metric is composite, emphasizing boundary principles and equilibration processes involving decoherence and entanglement.

Contribution

It demonstrates that Clausius-like relations are always constructible in emergent gravity models with composite metrics, linking thermodynamics to equilibration and decoherence mechanisms.

Findings

Clausius-like relations can be derived from boundary principles.

Thermodynamic behavior relates to equilibration and decoherence processes.

Entanglement influences the emergent thermodynamic properties of gravity.

Abstract

We examine the conditions under which the thermodynamic behaviour of gravity can be explained within an emergent gravity scenario, where the metric is defined as a composite operator. We show that due to the availability of a boundary of a boundary principle for the quantum effective action, Clausius-like relations can always be constructed. Hence, any true explanation of the thermodynamic nature of the metric tensor has to be referred to an equilibration process, associated to the presence of an H-theorem, possibly driven by decoherence induced by the pregeometric degrees of freedom, and their entanglement with the geometric ones.