Ultra-high energy collision with neither black hole nor naked singularity

TL;DR

This paper demonstrates that ultra-high energy particle collisions can occur without forming black holes or naked singularities, using a model of colliding charged and neutral shells in overcharged Reissner-Nordstrom spacetime.

Contribution

It introduces a shell collision model showing that extremely high-energy particle interactions are possible without black hole or naked singularity formation.

Findings

Collision energy can exceed the Planck scale due to high relative velocities.

Black holes or naked singularities are not required for ultra-high energy collisions.

Shell dynamics produce conditions for arbitrarily high particle energies.

Abstract

We explore the collision between two concentric spherical thin shells. The inner shell is charged, whereas the outer one is either neutral or charged. In the situation we consider, the charge of the inner shell is larger than its gravitational mass, and the inside of it is empty and regular. Hence the domain just outside it is described by the overcharged Reissner-Nordstrom geometry whereas the inside of it is Minkowski. First, the inner shell starts to shrink form infinity with finite kinetic energy, and then the outer shell starts to shrink from infinity with vanishing kinetic energy. The inner shell bounces on the potential wall and collides with the ingoing outer shell. The energy of collision between these shells at "their center of mass frame" does not exceed the total energy of the system. By contrast, by virtue of the very large gamma factor of the relative velocity of the shells, the energy of collision between two of the constituent particles of these shells at their center of mass frame can be much larger than the Planck scale. This result suggests that the black hole or naked singularity is not necessary for ultra-high energy collision of particles.