Third law of repetitive electric Penrose processes

TL;DR

This paper proposes a third-law-like principle for the repetitive electric Penrose process, showing that a Reissner-Nordström black hole's charge cannot be reduced to zero through finite iterative steps, revealing fundamental thermodynamic limits.

Contribution

It introduces a new third-law analog for the electric Penrose process, demonstrating fundamental limits on charge extraction from Reissner-Nordström black holes.

Findings

Reissner-Nordström black hole charge cannot reach zero via finite steps.

Repetitive electric Penrose process has a thermodynamic third-law analog.

Charge extraction is fundamentally limited by this third-law.

Abstract

Recently, Ruffini et al. [Phys. Rev. Lett. 134 (2025) 8, 081403] pointed out that the repetitive Penrose process cannot drain the entire extractable energy of a Kerr black hole. In this Letter, we alternatively point out the charge of a Reissner-Nordstr\"{o}m black hole cannot drop down to exactly zero via the repetitive electric Penrose process that is terminated after a finite number of iterative steps, indicating a new thermodynamical third-law analog for the repetitive electric Penrose process.