Boundary States and Black Hole Entropy

TL;DR

This paper derives black hole entropy by summing over boundary states characterized by energy, momentum, and boundary metrics, using functional integrals applicable to various black hole solutions.

Contribution

It introduces a universal framework for calculating black hole entropy through boundary state sums and functional integrals in any stationary, nonextreme black hole scenario.

Findings

Boundary states are labeled by energy and momentum densities.

Entropy is expressed as a sum over boundary states and metrics.

The approach applies universally to stationary, nonextreme black holes.

Abstract

Black hole entropy is derived from a sum over boundary states. The boundary states are labeled by energy and momentum surface densities, and parametrized by the boundary metric. The sum over state labels is expressed as a functional integral with measure determined by the density of states. The sum over metrics is expressed as a functional integral with measure determined by the universal expression for the inverse temperature gradient at the horizon. The analysis applies to any stationary, nonextreme black hole in any theory of gravitational and matter fields.