Statistical physics of black holes as quantum-mechanical systems

TL;DR

This paper explores the quantum statistical mechanics of black holes, examining how interactions affect entropy and equilibrium properties, and discusses the implications for models of black hole evolution.

Contribution

It analyzes the relationship between black hole entropy and quantum interactions, proposing that interactions may reduce entropy below the Bekenstein-Hawking value and affect equilibrium.

Findings

Interactions can produce extra energy flux beyond Hawking radiation

Black hole entropy may be smaller than Bekenstein-Hawking entropy due to interactions

Constraints on quantum black hole models from entropy inequalities

Abstract

Some basic features of black-hole statistical mechanics are investigated, assuming that black holes respect the principles of quantum mechanics. Care is needed in defining an entropy S_bh corresponding to the number of microstates of a black hole, given that the black hole interacts with its surroundings. An open question is then the relationship between this entropy and the Bekenstein-Hawking entropy S_BH. For a wide class of models with interactions needed to ensure unitary quantum evolution, these interactions produce extra energy flux beyond that predicted by Hawking. Arguments are then presented that this results in an entropy S_bh that is smaller than S_BH. Correspondingly, in such scenarios equilibrium properties of black holes are modified. We examine questions of consistency of such an inequality; if it is not consistent, that provides significant constraints on models for quantum-mechanical black hole evolution.