Statistical interpretation of Bekenstein entropy for systems with a stretched horizon

TL;DR

This paper demonstrates that for 2-charge extremal black holes in string theory, the Bekenstein entropy from the stretched horizon can be understood as a coarse-grained statistical entropy, linking geometry to microstates.

Contribution

It provides a statistical interpretation of Bekenstein entropy for extremal black holes using the concept of coarse graining at the stretched horizon.

Findings

Bekenstein entropy corresponds to a coarse graining entropy.

Different microstates lead to geometries that diverge near r=0.

The stretched horizon acts as a cutoff where geometries start to differ.

Abstract

For the 2-charge extremal holes in string theory we show that the Bekenstein entropy obtained from the area of the stretched horizon has a statistical interpretation as a `coarse graining entropy': different microstates give geometries that differ near r=0 and the stretched horizon cuts off the metric at r=b where these geometries start to differ.