The scattering matrix approach for the quantum black hole, an overview

TL;DR

This paper reviews a scattering matrix approach to quantum black holes, emphasizing horizon states and unitarity, offering new models and insights into black hole quantum dynamics beyond traditional quantum field theory assumptions.

Contribution

It introduces an alternative scattering matrix framework focusing on horizon states, providing novel models and understanding of quantum black hole dynamics.

Findings

Supports a unitary, pure quantum description of black holes.

Develops models that incorporate horizon degrees of freedom.

Provides insights into quantum dynamics in flat space-time.

Abstract

If one assumes the validity of conventional quantum field theory in the vicinity of the horizon of a black hole, one does not find a quantum mechanical description of the entire black hole that even remotely resembles that of conventional forms of matter; in contrast with matter made out of ordinary particles one finds that, even if embedded in a finite volume, a black hole would be predicted to have a strictly continuous spectrum. Dissatisfied with such a result, which indeed hinges on assumptions concerning the horizon that may well be wrong, various investigators have now tried to formulate alternative approaches to the problem of ``quantizing" the black hole. We here review the approach based on the assumption of quantum mechanical purity and unitarity as a starting point, as has been advocated by the present author for some time, concentrating on the physics of the states that should live on a black hole horizon. The approach is shown to be powerful in not only producing promising models for the quantum black hole, but also new insights concerning the dynamics of physical degrees of freedom in ordinary flat space-time.