Chronology Protection in anti-de Sitter

TL;DR

This paper links causality violations in certain AdS geometries to violations of the Pauli exclusion principle in their fermionic phase space, showing that unphysical fermion densities lead to closed timelike curves.

Contribution

It demonstrates a direct connection between fermionic probability density violations and causality issues in dual AdS geometries, providing insight into chronology protection.

Findings

Fermionic densities exceeding one or negative cause closed timelike curves.

Causality violations are linked to phase space violations of the Pauli principle.

The study clarifies conditions for physical, causality-preserving geometries.

Abstract

We consider 1/2 BPS excitations of AdS(5)xS(5) geometries in type IIB string theory that can be mapped into free fermion configurations according to the prescription of Lin, Lunin and Maldacena (LLM). It is shown that whenever the fermionic probability density exceeds one or is negative, closed timelike curves appear in the bulk. A violation of the Pauli exclusion principle in the phase space of the fermions is thus intimately related to causality violation in the dual geometries.