Black Hole Interiors

Kerr or Reissner-Nordström black holes have inner horizons which delineate the domain of predictability of solutions of wave equation type. Often, though not e.g. for certain (A)deSitter black holes, these inner horizons are classically dynamically unstable, and get turned into some sort of singularity by perturbations, and thus drastically changing the nature of the inner horizons relative to the underlying exact solutions, and relegating the problem of predictability to the real of quantum gravity ("strong cosmic censorship"). Recent work has shown that semi-classical quantum effects dominate classical ones very near the inner horizons, and are expected lead to singularity in cases where the inner horizon is stable classically. I review recent progress surrounding these issues.