Hawking and black holes. Illustration of British theoretical physicist and cosmologist Stephen Hawking (born 1942), with black holes and equations describing his work. Hawking has worked on topics such as gravitational singularity theorems (the Penrose-Hawking singularity theorems) and Hawking radiation. A black hole (centre) is formed when the core of a star collapses under its own weight, increasing the strength of its gravitational field to the point where usually nothing, not even light, can escape. Hawking radiation consists of particle-antiparticle pairs formed from the quantum vacuum, with one particle falling into the black hole and the other escaping by quantum tunnelling.