Black Hole Entropy and the Problem of Universality

TL;DR

This paper proposes a conformal field theory approach to derive black hole entropy, explaining its universality through horizon constraints and symmetry breaking, and suggests a Goldstone-boson-like picture of the degrees of freedom.

Contribution

It introduces a nearly model-independent method using horizon constraints and conformal symmetry to compute black hole entropy, shedding light on its universal nature.

Findings

Reproduces Bekenstein-Hawking entropy across various black holes.

Provides a symmetry-breaking perspective on black hole microstates.

Suggests a Goldstone-boson-like interpretation of horizon degrees of freedom.

Abstract

To derive black hole thermodynamics in any quantum theory of gravity, one must introduce constraints that ensure that a black hole is actually present. For a large class of black holes, the imposition of such ``horizon constraints'' allows the use of conformal field theory methods to compute the density of states, reproducing the correct Bekenstein-Hawking entropy in a nearly model-independent manner. This approach may explain the ``universality'' of black hole entropy, the fact that many inequivalent descriptions of quantum states all seem to give the same thermodynamic predictions. It also suggests an elegant picture of the relevant degrees of freedom, as Goldstone-boson-like excitations arising from symmetry breaking by a conformal anomaly induced by the horizon constraints.