Black hole information, unitarity, and nonlocality

TL;DR

This paper explores the black hole information paradox, examining nonlocality as a potential solution and arguing that strong gravitational dynamics, inherently nonlocal, are crucial for understanding information retention or loss.

Contribution

It investigates mechanisms of nonlocality in black hole physics, dismisses ultra-planckian modes as relevant, and emphasizes the importance of strong gravitational dynamics in resolving the paradox.

Findings

Ultra-planckian modes are not relevant to nonlocality mechanisms.

A reliable argument for information loss has not been established.

Strong gravitational dynamics are fundamentally nonlocal in extreme conditions.

Abstract

The black hole information paradox apparently indicates the need for a fundamentally new ingredient in physics. The leading contender is nonlocality. Possible mechanisms for the nonlocality needed to restore unitarity to black hole evolution are investigated. Suggestions that such dynamics arises from ultra-planckian modes in Hawking's derivation are investigated and found not to be relevant, in a picture using smooth slices spanning the exterior and interior of the horizon. However, no simultaneous description of modes that have fallen into the black hole and outgoing Hawking modes can be given without appearance of a large kinematic invariant, or other dependence on ultra-planckian physics; a reliable argument for information loss thus has not been constructed. This suggests that strong gravitational dynamics is important. Such dynamics has been argued to be fundamentally nonlocal in extreme situations, such as those required to investigate the fate of information.