Breakdown of Semiclassical Gravity in Four-Dimensional Black Hole Evaporation
David A. Lowe, Larus Thorlacius
TLDR
Semiclassical black hole evaporation models develop a "thunderbolt" singularity, signaling a breakdown of effective field theory and challenging the information paradox.
Key contributions
- Analyzes 4D semiclassical black hole evaporation with anomaly-induced quantum corrections.
- Identifies a "thunderbolt" singularity emerging after the horizon recedes, extending macroscopically.
- This thunderbolt signals a breakdown of semiclassical effective field theory at large distances.
- Challenges the standard formulation of the black hole information paradox.
Why it matters
This paper reveals a fundamental instability in semiclassical gravity, showing its limits in describing black hole evaporation. The discovery of the "thunderbolt" singularity suggests that the theory breaks down far from the black hole, which has profound implications for understanding quantum gravity and the black hole information paradox.
Original Abstract
We study black hole formation and evaporation in a four-dimensional semiclassical model that preserves diffeomorphism invariance and reproduces the one-loop trace anomaly. Solving the quantum-corrected Einstein equations for the collapse of a spherically symmetric null shell, we follow the formation and evaporation of a black hole with back-reaction included. The semiclassical solutions develop a spacelike thunderbolt singularity that emerges after the apparent horizon has receded and extends far from the black hole where the semiclassical curvature is a priori expected to be parametrically small. This behavior arises from a nonlinear instability of the higher-derivative semiclassical equations and is generic in models with anomaly-induced quantum corrections. The thunderbolt signals a breakdown of semiclassical effective field theory over macroscopic distances and undermines the standard formulation of the black hole information paradox.
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