Stephen Hawking

Stephen William Hawking was born in Oxford on 8 January 1942 — by his own telling, exactly three hundred years after the death of Galileo. He read physics at University College, Oxford, then moved to the University of Cambridge for graduate work in cosmology in 1962. The following year, at twenty-one, he was diagnosed with amyotrophic lateral sclerosis (motor neurone disease) and given roughly two years to live. He lived another fifty-five, doing his most important work from a wheelchair and, after a 1985 tracheotomy, communicating through a speech synthesizer that gave him his famous mechanical voice.

Hawking's early work, much of it with Roger Penrose, applied global differential-geometry techniques to general relativity and produced the singularity theorems: under broad and physically reasonable conditions, gravitational collapse must end in a spacetime singularity, and the universe must have begun in one. This recast the Big Bang and the centers of black holes as unavoidable consequences of Einstein's equations rather than artifacts of idealized symmetry. In 1971 he proved the area theorem — that the total area of black-hole horizons can never decrease — which seeded the thermodynamic analogy that Jacob Bekenstein soon pushed further.

His landmark result came in 1974. Attempting to refute Bekenstein's claim that black holes carry entropy, Hawking instead found that quantum fields in the spacetime of a collapsing star produce a steady thermal flux of particles: a black hole radiates as a blackbody at the temperature T_H = ℏc³/8πGMk_B and slowly evaporates. The discovery united, for the first time, gravity, quantum mechanics, and thermodynamics in a single equation, and immediately raised the information paradox that occupied physicists — and Hawking himself — for the rest of his life.

From 1979 to 2009 Hawking held the Lucasian Professorship of Mathematics at Cambridge, the chair once occupied by Isaac Newton. His 1988 popular book A Brief History of Time sold over ten million copies and made him the most recognizable scientist of his era. He continued working on quantum cosmology, the no-boundary proposal with James Hartle, and the information paradox until his death in Cambridge on 14 March 2018. His ashes were interred in Westminster Abbey between Newton and Darwin.