Particle Accelerators inside Spinning Black Holes

TL;DR

This paper demonstrates that particle collisions inside spinning black holes can reach infinite energy at the inner horizon, indicating classical instability and potential Planck-scale physics at macroscopic scales.

Contribution

It reveals that the divergence of collision energy occurs specifically in rotating black holes, highlighting a new form of internal instability distinct from known Cauchy horizon issues.

Findings

Divergent center-of-mass energy at the inner horizon of Kerr black holes

Instability of classical black holes with rotation

Potential for Planck-scale physics inside black holes

Abstract

On the basis of the Kerr metric as a model for a spinning black hole accreting test particles from rest at infinity, I show that the center-of-mass energy for a pair of colliding particles is generically divergent at the inner horizon. This shows that not only are classical black holes internally unstable, but also that Planck-scale physics is a characteristic feature within black holes at scales much larger that the Planck length. The novel feature of the divergence discussed here is that the phenomenon is present only for black holes with rotation and in this sense it is distinct from the well known Cauchy horizon instability.