Remarks about Static Back-Reaction on Black Hole Spacetimes

TL;DR

This paper critically examines claims that vacuum polarization back reaction regularizes black hole entropy infinities, finding no such regularization and confirming breakdown of perturbation near the horizon.

Contribution

It provides a detailed analysis showing the absence of a short-distance cutoff and confirms the divergence of surface gravity at the stretched horizon.

Findings

No short-distance regularization of entropy infinities

Perturbative calculations break down near the horizon

Surface gravity diverges at the stretched horizon

Abstract

Recently, it has been claimed that the back reaction of vacuum polarization on a black hole spacetime naturally regularizes infinities in the black hole entropy. We examine the back reaction calculation and find no such short-distance cut-off,in contradiction with these recent claims. Moreover, the intuitive expectation that the perturbative calculation breaks down near the event horizon is confirmed. The new surface gravity diverges and the metric is degenerate at the stretched horizon.