On the viability of regular black holes

Understand

The evaporation of black holes raises a number of conceptual issues, most of them related to the final stages of evaporation, where the interplay between the central singularity and Hawking radiation cannot be ignored.

• Regular models of black holes replace the central singularity with a nonsingular spacetime region, in which an effective classical geometric description is available.
• It has been argued that these models provide an effective, but complete, description of the evaporation of black holes at all times up to their eventual disappearance.
• However, here we point out that known models fail to be self-consistent: the regular core is exponentially unstable against perturbations with a finite timescale, while the evaporation time is infinite, therefore making the instability impossible to prevent.