Instability of Flat Space Enclosed in a Cavity

TL;DR

This paper demonstrates through numerical evidence that a massless scalar field confined within a spherical cavity can evolve from arbitrarily small initial disturbances into a black hole, highlighting the inherent instability of such a system.

Contribution

It provides the first numerical evidence that small generic initial data in a cavity lead to black hole formation, revealing the instability of flat space in this setting.

Findings

Small initial data can evolve into black holes.

The system exhibits instability under generic conditions.

Numerical simulations confirm black hole formation from minimal perturbations.

Abstract

We consider a spherically symmetric self-gravitating massless scalar field enclosed inside a timelike worldtube $R\times S^3$ with a perfectly reflecting wall. Numerical evidence is given that arbitrarily small generic initial data evolve into a black hole.