Stretched Horizon Dissipation and the Fate of Echoes

TL;DR

This paper explores how breaking the equivalence principle at the stretched horizon of black holes causes partial reflection of infalling particles, potentially allowing gravitational wave echoes to persist despite quantum effects.

Contribution

It introduces a universal model where horizon dissipation and echoes can survive without detailed microphysics, challenging traditional views on black hole information.

Findings

Moderate dissipation occurs when particle energy is near Hawking temperature.

Echoes may survive quantum gravitational effects due to partial reflection.

Decay rate is independent of the Planck mass.

Abstract

We examine the dissipation of infalling particles near black holes under the assumption that the equivalence principle breaks down at the stretched horizon. This violation allows partial reflection of particles just outside the event horizon, as suggested by models such as the fuzzball and firewall proposals. We show that scattering with blue-shifted Hawking radiation leads to moderate dissipation when the particle energy is comparable to the Hawking temperature. The decay rate is independent of the Planck mass, and therefore gravitational wave echoes-arising from such partial reflection-may survive despite the presence of quantum gravitational effects. Our result is universal and does not rely on the detailed microphysics of the horizon.