Comment on Counting Black Hole Microstates Using String Dualities

TL;DR

This paper critiques a string duality approach to counting black hole microstates, clarifying the conditions under which the dualities are valid and highlighting limitations related to spacetime asymptotics.

Contribution

It provides a justification for the dualities used in microstate counting and discusses the limitations when applying these methods to asymptotically flat spacetimes.

Findings

Dualities are justified in a near horizon limit.

Resulting spacetime is not asymptotically flat.

Clarifies conditions for microstate counting methods.

Abstract

We discuss a previous attempt at a microscopic counting of the entropy of asymptotically flat non-extremal black-holes. This method used string dualities to relate 4 and 5 dimensional black holes to the BTZ black hole. We show how the dualities can be justified in a certain limit, equivalent to a near horizon limit, but the resulting spacetime is no longer asymptotically flat.