Overcharging a Black Hole and Cosmic Censorship

TL;DR

This paper demonstrates that near-extremal Reissner-Nordstrom black holes can be overcharged by a charged particle under negligible backreaction, challenging the cosmic censorship conjecture, unlike the shell scenario which upholds it.

Contribution

It shows that overcharging black holes is possible with particles when backreaction is negligible, raising questions about the validity of cosmic censorship.

Findings

Overcharging black holes with particles is possible under certain conditions.

Backreaction effects can be made arbitrarily small with appropriate parameters.

Overcharging with a charged shell upholds cosmic censorship.

Abstract

We show that, contrary to a widespread belief, one can overcharge a near extremal Reissner-Nordstrom black hole by throwing in a charged particle, as long as the backreaction effects may be considered negligible. Furthermore, we find that we can make the particle's classical radius, mass, and charge, as well as the relative size of the backreaction terms arbitrarily small, by adjusting the parameters corresponding to the particle appropriately. This suggests that the question of cosmic censorship is still not wholly resolved even in this simple scenario. We contrast this with attempting to overcharge a black hole with a charged imploding shell, where we find that cosmic censorship is upheld. We also briefly comment on a number of possible extensions.