Discrete Black-Hole Radiation and the Information Loss Paradox

TL;DR

This paper explores how quantum gravity effects could cause black holes to emit discrete spectral lines, potentially allowing information to escape and addressing the black hole information paradox.

Contribution

It proposes that black holes have a discrete mass spectrum leading to line emission, which could carry information and resolve the paradox.

Findings

Black-hole radiation may be discrete rather than continuous.

Spectral lines can encode and release information.

Black-hole entropy may be lower than previously thought.

Abstract

Hawking's black hole information puzzle highlights the incompatibility between our present understanding of gravity and quantum physics. However, Hawking's prediction of black-hole evaporation is at a semiclassical level. One therefore suspects some modifications of the character of the radiation when quantum properties of the {\it black hole itself} are properly taken into account. In fact, during the last three decades evidence has been mounting that, in a quantum theory of gravity black holes may have a discrete mass spectrum, with concomitant {\it discrete} line emission. A direct consequence of this intriguing prediction is that, compared with blackbody radiation, black-hole radiance is {\it less} entropic, and may therefore carry a significant amount of {\it information}. Using standard ideas from quantum information theory, we calculate the rate at which information can be recovered from the black-hole spectral lines. We conclude that the information that was suspected to be lost may gradually leak back, encoded into the black-hole spectral lines.