Draft:Mass inflation

In general relativity, mass inflation is a phenomenon inside spinning or charged black holes in which the interactions of outgoing and ingoing radiation at the Cauchy horizon cause the internal gravitational mass parameter of the black hole to become unbounded at the Cauchy horizon. It also predicts the existence of a weak null singularity at the Cauchy horizon of a spinning or charged black hole.

Mass-inflation singularity

The divergence of the gravitational mass parameter has interesting local consequences for an extended infalling object: since the mass parameter determines the Coulomb component of the local curvature inside a black hole, an increase in the parameter would lead to increased tidal forces felt locally by the object.

Further implications

Non-determinism beyond the Cauchy horizon

After Roger Penrose pointed out in the 1960s that the Cauchy horizon of a black hole is a region of infinite blueshift and a barrier in which causality breaks down, the inherent non-predictability of spacetime beyond the horizon puzzled scientists for decades. This was especially problematic as it violated the classical view of determinism. It became the basis of Roger Penrose's 1979 strong cosmic censorship conjecture, in which he argued that the Cauchy horizon could not exist because any perturbations by passing gravitational waves would cause the horizon to collapse into a strong, spacelike singularity. However, the conjecture was proven false in 2018 by mathematicians Mihalis Dafermos and Jonathan Luk, who mathematically confirmed the existence of the singularity in Kerr spacetime. Despite this, the mathematicians discovered that the existence of a weak null singularity at the Cauchy horizon would prevent the existence of multiple solutions of Einstein's equations beyond the Cauchy horizon, thus saving determinism.They instead theorized that spacetime beyond the Cauchy horizon is not smooth enough to use Einstein's equations at all.