Würzburg Seminar on Quantum Field Theory and Gravity

Black hole formation and evaporation is studied in a four-dimensional model that preserves diffeomorphism invariance and reproduces the one-loop trace anomaly. The quantum corrected Einstein equations are solved numerically for an ingoing null shock wave. An apparent horizon forms and then recedes as the black hole evaporates due to Hawking emission. However, the semiclassical geometry then develops a spacelike “thunderbolt” singularity that extends far from the black hole where the curvature is a priori expected to be 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 the semiclassical effective field theory over macroscopic distances and undermines the formulation of the black hole information paradox.