Tunneling into Microstate Geometries: Quantum Effects Stop Gravitational Collapse

TL;DR

This paper demonstrates that quantum tunneling can cause collapsing shells to form horizonless microstate geometries, suggesting classical general relativity may break down earlier than expected during gravitational collapse.

Contribution

It provides explicit calculations showing quantum tunneling into microstate geometries occurs more readily than previously thought, challenging classical collapse assumptions.

Findings

Quantum tunneling amplitude into microstate geometries is significantly large.

Shells can tunnel into horizonless configurations before horizon formation.

Quantum effects can prevent classical gravitational collapse.

Abstract

Collapsing shells form horizons, and when the curvature is small classical general relativity is believed to describe this process arbitrarily well. On the other hand, quantum information theory based (fuzzball/firewall) arguments suggest the existence of some structure at the black hole horizon. This structure can only form if classical general relativity stops being the correct description of the collapsing shell before it reaches the horizon size. We present strong evidence that classical general relativity can indeed break down prematurely, by explicitly computing the quantum tunneling amplitude of a collapsing shell of branes into smooth horizonless microstate geometries. We show that the amplitude for tunneling into microstate geometries with a large number of topologically non-trivial cycles is parametrically larger than exp(-S), which indicates that the shell can tunnel into a horizonless configuration long before the horizon has any chance to form. We also use this technology to investigate the tunneling of M2 branes into LLM bubbling geometries.