Hawking Radiation and Unitary evolution

TL;DR

This paper presents exact solutions in 2D dilaton gravity showing how Hawking radiation can occur without black hole formation, preserving unitarity and transferring information efficiently.

Contribution

It introduces new exact solutions demonstrating information-preserving Hawking radiation in scenarios without black hole formation.

Findings

Hawking radiation can occur without black hole formation.

Negative energy bursts preserve unitarity.

Information transfer exceeds positive energy bounds.

Abstract

We find a family of exact solutions to the semi-classical equations (including back-reaction) of two-dimensional dilaton gravity, describing infalling null matter that becomes outgoing and returns to infinity without forming a black hole. When a black hole almost forms, the radiation reaching infinity in advance of the original outgoing null matter has the properties of Hawking radiation. The radiation reaching infinity after the null matter consists of a brief burst of negative energy that preserves unitarity and transfers information faster than the theoretical bound for positive energy.