Which scientist did Hawking collaborate with on black hole singularities?

Stephen Hawking collaborated with Roger Penrose on the singularities predicted by general relativity, including those associated with black holes and the beginning of the universe.

Penrose had previously shown that gravitational collapse could produce a singularity under physically realistic conditions. Hawking extended and adapted these ideas to cosmology, helping demonstrate that singularities were not merely mathematical oddities arising from overly simple models. Their combined results became known as the Penrose–Hawking singularity theorems.

The theorems use the geometry of spacetime and assumptions about gravity and matter to show that certain conditions lead to geodesic incompleteness—a technical sign that classical general relativity reaches a boundary where its description breaks down. In black-hole formation, the result supports the prediction that a singularity forms inside the event horizon. Related reasoning points backward toward a singular beginning of the universe.

Hawking and Penrose shared the 1988 Wolf Prize in Physics for this work. Penrose later received half of the 2020 Nobel Prize in Physics for discovering that black-hole formation is a robust prediction of general relativity. The collaboration is why Roger Penrose is the canonical answer.