Strong Cosmic Censorship in Two Dimensions

TL;DR

This paper investigates the behavior of scalar waves near the Cauchy horizon of an AdS2 black hole, showing that the waves remain smooth, which suggests a potential violation of the strong cosmic censorship conjecture at the classical level.

Contribution

It demonstrates that scalar wave-packets can remain infinitely differentiable at the Cauchy horizon in AdS2 black holes, challenging the classical strong cosmic censorship conjecture.

Findings

Scalar waves become infinitely differentiable near the Cauchy horizon

The result holds regardless of spacetime or scalar parameters

Indicates a classical violation of strong cosmic censorship

Abstract

We study the behaviour of a free massive scalar wave-packet near the Cauchy horizon of an $\mathrm{AdS}_2$ black hole and find that it becomes infinitely differentiable for smooth initial data, independently of the parameters describing the spacetime or the scalar. This indicates a violation of the strong cosmic censorship conjecture at the classical level. We discuss our result in connection with some recent observations of violation of the conjecture for certain nearly extremal black holes.