Counting Schwarzschild and Charged Black Holes

TL;DR

This paper reviews the correspondence between string states and black hole states, demonstrating that black hole entropy can be derived from string theory, especially for non-extreme black holes, with some limitations on the exact numerical match.

Contribution

It introduces a method applicable to Schwarzschild and highly non-extreme charged black holes to derive their entropy from string theory, extending beyond D-brane approaches.

Findings

Black hole entropy proportional to horizon area

Numerical coefficient matches Bekenstein-Hawking only with central charge six

Method applicable to non-extreme and Schwarzschild black holes

Abstract

We review the arguments that fundamental string states are in one to one correspondence with black hole states. We demonstrate the power of the assumption by showing that it implies that the statistical entropy of a wide class of nonextreme black holes occurring in string theory is proportional to the horizon area. However, the numerical coefficient relating the area and entropy only agrees with the Bekenstein--Hawking formula if the central charge of the string is six which does not correspond to any known string theory. Unlike the current D-brane methods the method used in this paper is applicable for the case of Schwarzschild and highly non-extreme charged black holes.