Gerald Guralnik (1936–2014) Physicist Who Helped to Conceive the Higgs Boson

COMMENT OBITUARY Gerald Guralnik (1936–2014) Physicist who helped to conceive the Higgs boson.

erald Guralnik is best known for François Englert and Robert Brout at the which explains both the electromagnetic his work on the Higgs mechanism, Université Libre de Bruxelles in Belgium, and weak interactions. Steven Weinberg which confers mass on particles. and the other by Peter Higgs at the Uni- and Salam married this mechanism with a GAlong with particle physicist Carl Hagen versity of Edinburgh, UK) that addressed preliminary unified model proposed ear- and myself, he wrote one of three key the problem of giving mass to bosons from lier by Sheldon Glashow, thus resolving its papers published in 1964 that each took inconsistencies. For this work, the three of different routes to solving a conundrum of them shared the 1979 Nobel Prize in Physics. how particles interact. The validity of the Higgs mechanism Guralnik died of a heart attack on 26 April, was finally demonstrated in 2012, with the aged 77, shortly after finishing a lecture at experimental discovery of the Higgs boson, Brown University in Providence, Rhode which last year led to another Nobel Prize, Island, where he had been a faculty mem- for Englert and Higgs, the surviving authors ber since 1967. He was born in Cedar Falls, of the first two papers putting forth the UNIV. MIKE COHEA/BROWN Iowa, where his parents ran an accountancy mechanism. firm. Guralnik attended the Massachusetts The 1979 prizewinners carefully cited Institute of Technology (MIT) in Cam- all three of the 1964 papers on an equal bridge. He then went on to Harvard Univer- footing, but others have not always done sity, also in Cambridge, to study for a PhD so. Guralnik came to feel that our early under Walter Gilbert, who was working on paper was often unfairly neglected. He the theory of elementary particles before gave talks and wrote papers pointing out embarking on his Nobel-prizewinning our distinctive contribution, of which he experiments for DNA sequencing. was justifiably proud, and in which he was In 1964, Guralnik completed his doctor- unquestionably the prime mover. ate in quantum field theory, which models In the meantime, Guralnik had gone on subatomic particles as physical fields that to contribute much to the development of extend throughout space. That same year, computational approaches to quantum field he won a US National Science Foundation theory. From 1985 to 1987, as a staff mem- fellowship to a theoretical physics research different perspectives. All three papers ber at Los Alamos National Laboratory in group, founded by Gilbert’s former adviser showed that the mechanism could success- New Mexico, he used such approaches to Abdus Salam, at Imperial College London. fully use spontaneous symmetry breaking, make important contributions to quantum In the years after the Second World War, in which the underlying physics is symmet- chromodynamics, the theory of strong the success of quantum electrodynamics, ric but its realization is not. For example, interactions, which explains that quarks which describes the electromagnetic force a bowl of water is rotationally symmetric, interact through a ‘colour force’. Later, that drives interactions between matter and until it freezes and the ice crystals break the he worked on how chaos theory could light, had spurred work on similar theories symmetry. A particular contribution of our be applied to particle physics. He also of other interactions. A key goal was a uni- paper was to show how spontaneous sym- made significant contributions to string fied theory of the electromagnetic force and metry breaking could occur consistently theory, some in collaboration with his son, the weak force, which is observed in radio- within the formal structure of the theory. Zachary Guralnik. active β-decay and the Sun’s core. The big The three papers reached essentially the Gerry was always good company and problem was that to explain the short range same conclusions, and were later selected had a great sense of humour. As well as of the weak forces, the bosons transmitting by Physical Review Letters (the journal in being passionate about physics, he was them had to have large masses. By contrast, which they were published) as among the enthusiastic about many things: fast cars, the electromagnetic force is carried over most significant of 1964. photography and state-of-the-art comput- vast distances by the massless photon. The publications attracted few citations ers. Gerry was a member of Brown’s Ersatz When I met Guralnik in 1964 at Impe- in their first three years. Guralnik toured Brain Project, which aims to design a brain- rial, I was interested to learn that he, too, Europe and gave talks to sceptical audi- like computer. He could be combative when was concerned with the problem of boson ences. Werner Heisenberg, known for others failed to live up to his exacting stand- mass. Hagen, his friend and former MIT formulating the eponymous uncertainty ards, but he was warm and generous. classmate, also came to Imperial, and the principle, told him that he was talking Gerry once wrote that being able to work three of us worked together to find a solu- nonsense. When Guralnik won a postdoc as a theoretical physicist was a privilege; his tion. We were constant lunch companions. position at the University of Rochester in colleagues felt the privilege was theirs. ■ Guralnik enjoyed the work but often com- New York, the head of the group urged him plained about the food — especially Scotch to switch to a different field (later admitting Tom Kibble is emeritus professor of eggs (hard-boiled eggs baked into a grainy that the advice was misguided). theoretical physics at Imperial College coating of sausage meat and breadcrumbs). Our proposal, now generally known as the London. He worked there with Gerald Just as our paper was in its final draft, Higgs mechanism, is the cornerstone of the Guralnik in the 1960s. we discovered two earlier papers (one by well-established unified electroweak theory, e-mail: [email protected]