Large entropy production inside black holes: a simple model

TL;DR

This paper presents a simple model demonstrating that high-energy particle collisions inside rotating black holes produce entropy exceeding the horizon entropy increase, consistent with thermodynamic laws and within entropy bounds.

Contribution

Introduces a model where neutrons dropped into a black hole collide near the inner horizon, producing significant entropy without violating entropy bounds or thermodynamic laws.

Findings

Collision entropy exceeds horizon entropy increase by a factor of two.

Entropy produced inside the black hole does not violate Bousso's bound.

The model aligns with the generalized laws of black hole thermodynamics.

Abstract

Particles dropped into a rotating black hole can collide near the inner horizon with enormous energies. The entropy produced by these collisions can be several times larger than the increase in the horizon entropy due to the addition of the particles. In this paper entropy is produced by releasing large numbers of neutrons near the outer horizon of a rotating black hole such that they collide near the inner horizon at energies similar to those achieved at the Relativistic Heavy Ion Collider. The increase in horizon entropy is approximately 80 per dropped neutron pair, while the entropy produced in the collisions is 160 per neutron pair. The collision entropy is produced inside the horizon, so this excess entropy production does not violate Bousso's bound limiting the entropy that can go through the black hole's horizon. The generalized laws of black hole thermodynamics are obeyed. No individual observer inside the black hole sees a violation of the second law of thermodynamics