Long time scales and eternal black holes

TL;DR

This paper examines the temporal behavior of correlation functions in eternal black holes, highlighting the limitations of semiclassical gravity and exploring how quantum effects influence unitarity and Poincare recurrences.

Contribution

It identifies the failure of semiclassical gravity to uphold unitarity bounds and shows that quantum corrections via a master field partially restore this, suggesting the need for additional configurations.

Findings

Semiclassical gravity fails to respect unitarity bounds.

Quantum corrections via a master field improve unitarity compliance.

Additional configurations are necessary to fully explain Poincare recurrences.

Abstract

We discuss the various scales determining the temporal behaviour of correlation functions in the presence of eternal black holes. We point out the origins of the failure of the semiclassical gravity approximation to respect a unitarity-based bound suggested by Maldacena. We find that the presence of a subleading (in the large-N approximation involved) master field does restore the compliance with one bound but additional configurations are needed to explain the more detailed expected time dependence of the Poincare recurrences and their magnitude.