The launch in the 1950s of Sputnik, the world’s first artificial satellite, played an unexpected but important role in propelling Anthony Leggett towards his 2003 Nobel prize for physics. Leggett, who was to become a world-leading researcher in the field of low-temperature physics, had, in 1959, just graduated in greats, a combination of classical literature, ancient history and philosophy, at Balliol College, Oxford. A career in classical academia or the civil service beckoned.
Leggett wanted neither. His academic aspirations had changed and his desire now was to become a physicist in order “to make meaningful conjectures about the way the world works”. However he would have had little chance, financially, of pursuing a second undergraduate degree straight after graduating had it not been for the launch by the Soviet Union of Sputnik 18 months earlier.
It turned out to be “the most serendipitous event”, he later recalled. The west had been caught out technologically because “we had encouraged all our best brains to study useless subjects, such as classics, rather than useful ones, such as science and engineering and particularly physics”.
To correct this failing, scholarships were quickly made available to encourage arts students to transfer to science, and one of these was given to Leggett so he could study physics at Merton College, Oxford, where he gained a first in two years.
Leggett, who has died aged 87, put his new expertise to good use, quickly building up a strong reputation for his work in showing how our everyday world is influenced by quantum mechanics, the branch of physics which describes the probabilistic – sometimes bizarre – behaviour of matter and light at atomic and subatomic levels.
These interests led him to carry out low-temperature studies of superfluids, liquids that can flow without friction or energy loss and that exhibit various odd behaviours, including the ability to flow up the side and over the tops of containers. He also worked on superconductors, materials that conduct electricity without resistance and that are critical to the construction of MRI scanners, particle accelerators and maglev trains.
This pioneering work, undertaken in the 1970s at Sussex University, culminated in his theory that explained how certain atoms, in particular those of the rare, light isotope of helium known as helium-3, interacted in the superfluid state and behaved in their frictionless fashion. To do this, Leggett showed that electrons in helium-3 form pairs in a highly complicated but predictable manner, a discovery that found wide application in many other areas of science, ranging from cosmology to the study of subatomic particles and liquid crystals.
It also led directly to his award, in 2003, of the Nobel prize for physics, which he shared with the Russians Alexei Abrikosov and Vitaly Ginzburg, for “pioneering contributions to the theory of superconductors and superfluids”. In its citation, the Nobel committee specifically stressed the importance of Leggett’s work in helping to opening up research in other fields, such as cosmology.
“Tony was always way ahead of the rest of us, owing not simply to his being smarter, but also to his boundless energy,” said the physicist Gordon Baym, of the University of Illinois Urbana-Champaign, where Leggett held the post of professor of physics from 1983 until his retirement in 2019. “His enthusiasm for physics and people continued to the end.”
As Leggett put it himself: “Remember that no piece of honestly conducted research is ever wasted, even if it seems so at the time. Put it away in a drawer, and 10, 20 or 30 years down the road, it will come back and help you in ways you never anticipated.”
Leggett was born in Camberwell, south London. His father, Richard, and his mother Winifred (nee Regan), were each the first in their families to receive a university education. Both became teachers and both were Catholics, a faith that turned their five children – Leggett later claimed – into “members of a small embattled minority in England”, a factor that also helped to produce his intense sense of iconoclasm, he believed.
Tony, as he was widely known, attended Beaumont college, a Jesuit school near Windsor in Berkshire, where his father taught physics and chemistry, and which had an unspoken tradition for all academically gifted pupils to be channelled into classics; hence his later arrival at Balliol to read greats. However, one teacher had provided Leggett with private mathematics lessons and these provided the spark that turned him away from classics to the world of science – with a little help from Sputnik.
After Oxford, Leggett worked as a postdoctoral research assistant in 1964-65 at the University of Illinois before spending a year at Kyoto University, where he lived with typical intensity and fervour, sharing dormitories with Japanese undergraduates, learning their language and avoiding other foreign students. This behaviour – he later learned – triggered the widely held belief he was a trainee CIA agent.
He returned to Britain in 1967 as a lecturer in physics (subsequently reader and, in 1978, professor) at Sussex University, and began the work that would earn him the Nobel prize. He moved to Illinois in 1983 while also holding subsequent positions at the Institute for Quantum Computing in Waterloo, Canada, and the Shanghai Center for Complex Physics at Shanghai Jiao Tong University.
His awards included the Wolf prize in physics (2002-03), the Paul Dirac medal and prize (1992) and the James Clerk Maxwell medal and prize (1975). He was elected a fellow of the Royal Society in 1980, and in 2004 was knighted for services to physics.
Leggett is survived by his wife, Haruko Kinase-Leggett, who he met at Sussex University and married in 1973, their daughter, Asako, and his sisters, Judith and Clare. His younger brothers, Terence and Paul, predeceased him.
• Anthony James Leggett, theoretical physicist, born 26 March 1938; died 8 March 2026
