COMMENT OBITUARY Stephen Hawking (1942–2018) World-renowned physicist who defied the odds. hen Stephen Hawking was speech synthesizer processed his words and diagnosed with motor-neuron generated the androidal accent that became disease at the age of 21, it wasn’t his trademark. In this way, he completed his Wclear that he would finish his PhD. Against best-selling book A Brief History of Time all expectations, he lived on for 55 years, (Bantam, 1988), which propelled him to becoming one of the world’s most celebrated celebrity status. IAN BERRY/MAGNUM scientists. Had Hawking achieved equal distinction Hawking, who died on 14 March 2018, was in any other branch of science besides cos- born in Oxford, UK, in 1942 to a medical- mology, it probably would not have had the researcher father and a philosophy-graduate same resonance with a worldwide public. As mother. After attending St Albans School I put it in The Telegraph newspaper in 2007, near London, he earned a first-class degree “the concept of an imprisoned mind roaming in physics from the University of Oxford. He the cosmos” grabbed people’s imagination. began his research career in 1962, enrolling In 1965, Stephen married Jane Wilde. as a graduate student in a group at the Uni- After 25 years of marriage, and three versity of Cambridge led by one of the fathers children, the strain of Stephen’s illness of modern cosmology, Dennis Sciama. and of sharing their home with a team of The general theory of relativity was at that nurses became too much and they sepa- time undergoing a renaissance, initiated in rated, divorcing in 1995. Jane wrote a book part by Roger Penrose at Birkbeck College, about their life together, Travelling to Infinity London, who had introduced new math- (Alma, 2008), and both she and Stephen ematical techniques. These showed that were happy with the telling of their story generic gravitational collapse would lead to in the 2014 film The Theory of Everything singularities — infinities that signal the need (although it elides and conflates Stephen’s for new physics. was that the radiation would cause black science). After a second, briefer marriage, The implications for black holes and holes to ‘evaporate’. This process would be Stephen was supported by an entourage of the Big Bang were developed by Hawking unobservably slow, except in ‘mini-holes’ assistants, as well as his family. in a series of papers collated in the 1973 the size of atoms — and these are thought Stephen remained remarkably positive monograph The Large Scale Structure not to exist. Yet Hawking radiation — and throughout his life, despite the immense of Space-Time (Cambridge University the related issue of whether information frustration that his condition clearly caused. Press), co-authored with George Ellis, a that falls into a black hole is lost or is some- He enjoyed theatre and opera trips, and he near-contemporary who had also been a how recoverable from the radiation — was a seemed energized rather than exhausted student of Sciama. Especially important profound issue, and one that still engenders by his travels to all parts of the world, as was the realization that the area of black controversy among theoretical physicists. well as by his regular trips to the California holes’ horizons (‘one-way membranes’ that Indeed, theorist Andrew Strominger at Institute of Technology in Pasadena. He shroud the singularities, and from within Harvard University in Cambridge, Massa- retained robust common sense and a sense which nothing can escape) could never chusetts, said in 2016 that one of Hawking’s of humour, expressed forceful opinions, decrease. The analogy with entropy — a papers on the subject (S. W. Hawking supported political causes and was happy to measure of disorder that likewise can Phys. Rev. D 14, 2460–2473; 1976) had engage with the media, despite its insistent never decrease — was developed further caused “more sleepless nights among theo- attention. His comments gained outsized by physicist Jacob Bekenstein. retical physicists than any paper in history”. attention even on subjects in which he was These findings gained Hawking election By the end of the 1970s, Hawking had not a specialist, such as philosophy and the to the Royal Society in London in 1974, at been appointed to the Lucasian Chair dangers of artificial intelligence. the age of 32. By then, he was so frail that of Mathematics at Cambridge (former Stephen’s expectations when he was both movement and speech were difficult, incumbents include Isaac Newton and Paul diagnosed dropped to zero; he said that and most of us suspected that his days in Dirac); he held the post until he retired in every thing that had happened since had front-line research were numbered. But in 2009. During these years, in which his focus been a bonus. And what a bonus — for phys- that same year, he came up with his most shifted to the quantum aspects of the Big ics, for the millions enlightened by his books distinctive contribution to science: Hawking Bang, the issue of information loss in black and for the even larger number inspired by radiation. holes continued to challenge him. his achievement against all the odds. ■ By linking quantum theory and gravity, In 1985, Stephen underwent a Hawking showed that a black hole would not trache otomy, which removed his already Martin Rees is Astronomer Royal of the be completely black, but would radiate with limited powers of speech. He was able United Kingdom. He was a student in a well-defined temperature that depended to control a cursor on a screen and type Dennis Sciama’s research group at the inversely on its mass (S. W. Hawking Nature out sentences — albeit with increasingly University of Cambridge at the same time as 248, 30–31; 1974). Black-hole entropy was painful slowness (first with his hand, and Stephen Hawking. more than just an analogy. The implication eventually only with a cheek muscle). A e-mail: [email protected] 444 | NATURE | VOL 555 | 22 MARCH©20 201818 Mac millan Publishers Li mited, part of Spri nger Nature. All ri ghts reserved. .