Roger Penrose

Sir Roger Penrose, born in 1931, is a British mathematician and theoretical physicist and the single most important scientific collaborator of Hawking's career. A figure of extraordinary range, he has made fundamental contributions to mathematics, physics and the study of the mind.

His own work

Penrose is celebrated for an unusually wide body of work. In pure mathematics he devised the famous Penrose tilings, patterns that cover a surface without ever repeating. In physics he developed twistor theory, an ambitious attempt to rebuild the foundations of spacetime, and the Penrose process, a way of extracting energy from a rotating black hole. He is also known to the wider public for books such as The Emperor's New Mind, in which he argued, controversially, that human consciousness cannot be explained by computation alone.

In 2020 Penrose was awarded a share of the Nobel Prize in Physics for showing that the formation of black holes is a robust prediction of general relativity, the very line of work he had begun in the 1960s.

His connection to Hawking

It was Penrose who, in 1965, first proved that a collapsing star must form a singularity, using powerful new geometric and topological methods rather than tracking the messy details of the collapse. The young Hawking seized on these techniques and, crucially, ran the argument in reverse, applying it to the whole expanding universe to show that it too must have begun from a singularity.

The two went on to develop and strengthen these results together, culminating in the joint Penrose-Hawking singularity theorems around 1970, among the most influential results in twentieth-century physics. Penrose's geometric way of thinking, reasoning about the global shape of spacetime rather than grinding through equations, profoundly shaped how Hawking approached physics for the rest of his life. Their collaboration is the clearest example of how far from solitary Hawking's greatest work really was.