Caricature of Professor Roger Penrose (born 1931), British mathematician. Roger Penrose's career began in 1965, when he mathematically proved that gravitational singularities (places, such as black holes, where gravity becomes infinite according to measurements) could be formed from the collapse of immense dying stars. In 1971, he invented graphs (spin networks) to explain the geometric structure of spacetime in the universe, for which he became a Fellow of the Royal Society in 1972. Penrose is also well known for his impossible diagrams, such as the Penrose stairway, seen in artist M. C. Escher's illustration Ascending and Descending. He has published several books and been awarded many prizes for his work.