The Absence of Horizon in Black-Hole Formation

TL;DR

This paper demonstrates that when considering Hawking radiation back-reaction, a collapsing body with spherical symmetry does not form an event horizon, which could resolve the black hole information paradox.

Contribution

It relaxes previous assumptions to show that collapsing matter remains outside the Schwarzschild radius, preventing horizon formation and addressing the information loss paradox.

Findings

No event horizon forms during collapse with Hawking radiation back-reaction.

The exterior geometry approximates that of a white-hole horizon.

Collapse evaporation occurs within finite time, avoiding horizon formation.

Abstract

With the back-reaction of Hawking radiation taken into consideration, the work of Kawai, Matsuo and Yokokura has shown that, under a few assumptions, the collapse of matter does not lead to event horizon nor apparent horizon. In this paper, we relax their assumptions and elaborate on the space-time geometry of a generic collapsing body with spherical symmetry. The geometry outside the collapsing sphere is found to be approximated by the geometry outside the white-hole horizon, hence the collapsing matter remains outside the Schwarzschild radius. As particles in Hawking radiation are created in the vicinity of the collapsing matter, the information loss paradox is alleviated. Assuming that the collapsing body evaporates within finite time, there is no event horizon.