Supertube domain-walls and elimination of closed time-like curves in string theory

TL;DR

This paper demonstrates that supertubes form domain-walls in string theory, which naturally eliminate closed time-like curves in supersymmetric spaces by creating non-differentiable boundaries, thus preventing causality violations behind black hole horizons.

Contribution

The study introduces a novel mechanism where supertubes form domain-walls that remove closed time-like curves in supersymmetric geometries, linking supertube physics with causality preservation.

Findings

Supertubes form domain-walls that eliminate closed time-like curves.

Inside the domain-wall, the metric is of G"odel type; outside, it resembles a rotating black hole.

This mechanism prevents closed time-like curves behind black hole horizons.

Abstract

We show that some novel physics of supertubes removes closed time-like curves from many supersymmetric spaces which naively suffer from this problem. The main claim is that supertubes naturally form domain-walls, so while analytical continuation of the metric would lead to closed time-like curves, across the domain-wall the metric is non-differentiable, and the closed time-like curves are eliminated. In the examples we study the metric inside the domain-wall is always of the G\"odel type, while outside the shell it looks like a localized rotating object, often a rotating black hole. Thus this mechanism prevents the appearance of closed time-like curves behind the horizons of certain rotating black holes.