How Not to Extract Information From Black Holes: Cosmic Censorship as a Guiding Principle

TL;DR

This paper investigates whether quantum effects in Hawking evaporation can lead to violations of cosmic censorship by analyzing simplified models of charged black hole evaporation, highlighting the importance of model assumptions.

Contribution

It demonstrates that limiting the spectrum of emitted particles to a finite set can worsen the tendency towards naked singularities, challenging cosmic censorship.

Findings

Finite particle species can lead to naked singularities.

Simplistic models may underestimate the risk of cosmic censorship violation.

The need for realistic models in black hole evaporation studies.

Abstract

Black holes in general relativity are commonly believed to evolve towards a Schwarzschild state as they gradually lose angular momentum and electrical charge under Hawking evaporation. However, when Kim and Wen applied quantum information theory to Hawking evaporation and argued that Hawking particles with maximum mutual information could dominate the emission process, they found that charged black holes tend towards extremality. In view of some evidence pointing towards extremal black holes being effectively singular, this would violate the cosmic censorship conjecture. Nevertheless, since the Kim-Wen model is too simplistic (e.g. it assumes a continuous spectrum of particles with arbitrary charge-to-mass ratio), one might hope that a more realistic model could avoid this problem. In this work, we show that having only a finite species of charged particles would actually worsen the situation, with some end states becoming a naked singularity. With this model as an example, we emphasize the need to study whether charged black holes can violate cosmic censorship under a given model of Hawking evaporation.