Penrose–Hawking singularity theorems

The Penrose–Hawking singularity theorems (after Roger Penrose and Stephen Hawking) are a set of results in general relativity that attempt to answer the question of when gravitation produces singularities. The Penrose singularity theorem is a theorem in semi-Riemannian geometry and its general relativistic interpretation predicts a gravitational singularity in black hole formation.

Source: Wikipedia — Penrose–Hawking singularity theorems (CC BY-SA 4.0)