Return of the quantum cosmic censor

TL;DR

This paper reexamines the cosmic censorship hypothesis in the context of quantum effects, demonstrating that quantum considerations prevent black holes from being over-spun and exposing singularities, thus supporting the principle.

Contribution

It shows that quantum effects uphold the cosmic censorship hypothesis in scenarios where classical physics suggests violations.

Findings

Quantum effects prevent black holes from being over-spun.

The integrity of the event horizon is maintained when quantum effects are included.

Supports the idea that cosmic censorship is fundamentally a quantum phenomenon.

Abstract

The influential theorems of Hawking and Penrose demonstrate that spacetime singularities are ubiquitous features of general relativity, Einstein's theory of gravity. The utility of classical general relativity in describing gravitational phenomena is maintained by the cosmic censorship principle. This conjecture, whose validity is still one of the most important open questions in general relativity, asserts that the undesirable spacetime singularities are always hidden inside of black holes. In this Letter we reanalyze extreme situations which have been considered as counterexamples to the cosmic censorship hypothesis. In particular, we consider the absorption of fermion particles by a spinning black hole. Ignoring quantum effects may lead one to conclude that an incident fermion wave may over spin the black hole, thereby exposing its inner singularity to distant observers. However, we show that when quantum effects are properly taken into account, the integrity of the black-hole event horizon is irrefutable. This observation suggests that the cosmic censorship principle is intrinsically a quantum phenomena.