Black Holes: Classical Properties, Thermodynamics and Heuristic Quantization

TL;DR

This paper explores classical and quantum properties of black holes, including no hair theorems, superradiance phenomena, and the quantization of horizon area, proposing a discrete mass spectrum and potential observable effects.

Contribution

It introduces a heuristic approach to black hole quantization, linking horizon area invariance to a discrete spectrum and analyzing superradiance in laboratory contexts.

Findings

Horizon area acts as an adiabatic invariant.

Quantum horizon area likely quantized in discrete units.

Black hole mass spectrum predicted to be nearly evenly spaced.

Abstract

I discuss the no hair principle, the recently found hairy solutions, generic properties of nonvacuum spherical static black holes, and the new no scalar hair theorems. I go into the generic phenomenon of superradiance, first uniform linear motion superradiance, then Kerr black hole superradiance, and finally general rotational superradiance and its possible applications in the laboratory. I show that the horizon area of a nearly stationary black hole can be regarded as an adiabatic invariant. This invariance suggests that quantum horizon area is quantized in multiples of a basic unit. Consideration of the quantum version of the Christodoulou reversible processes provides support for this idea. Horizon area quantization dictates a definite discrete black hole mass spectrum, so that Hawking's semiclassical spectrum is predicted to be replaced by a spectrum of nearly uniformly spaced lines whose envelope is roughly Planckian. Line natural broadening seems not enough to wash out the lines. To check on the possibility of line splitting, I present a simple algebra involving, among other operators, the black hole observables. Under simple assumptions it also leads to the uniformly spaced area spectrum.