Matter and forces near physical black holes

We describe general features of formation and disappearance of regular spherically symmetric black holes in semiclassical gravity. The allowed models are critically dependent on the requirement that the resulting objects evolve in finite time according to a distant observer. Violation of the null energy condition is mandatory for this to happen, and we study the properties of the necessary energy-momentum tensor in the vicinity of the apparent horizon. In studies of the kinematics of massive test particles, it is found that the escape from a black hole is possible only on the ingoing trajectories when the particles are overtaken by the contracting outer apparent horizon. Tidal forces experienced by geodesic observers, infalling or escaping, are shown to be finite at the apparent horizon, although this is not true for nongeodesic trajectories.

Automated summary

This article describes the general features of formation and disappearance of regular spherically symmetric black holes in semiclassical gravity. It emphasizes that the escape from a black hole is only possible when the particles are overtaken by the contracting outer apparent horizon. Furthermore, the study also found that the tidal forces experienced by observers at the apparent horizon are finite, but this is not true for non-geodesic trajectories.