Sir Tom Kibble
Brilliant physicist whose researches contributed to the discovery of the Higgs boson particle
SIR TOM KIBBLE, who has died aged 83, was a leading British particle physicist whose work helped lead to the discovery of the Higgs boson, a sub-atomic particle named after Peter Higgs, the Edinburgh University physicist who in 1964 proposed its existence; when Higgs was awarded the Nobel Prize in Physics (with François Englert) in 2013, he said that Kibble should have been the third person on the podium.
The search for the elusive particle began in the 1960s when three groups of scientists, working separately, were trying to build up quantum field theory, a mathematical description of the ways in which electromagnetic and nuclear forces interact at subatomic levels, in particular to solve the mystery of why some particles and objects are heavier than others – and why some have no mass at all.
Without some mechanism to account for this phenomenon, particles would never have coalesced into the complex structures that we see today, and everything from gorillas to galaxies would not exist. The Higgs boson, or “God Particle” as it also became known, explains how mass was imparted to elementary particles just after the Big Bang. Its discovery would put the final pieces into place for what is known as the Standard Model of particle physics.
There were six people involved in publishing scientific papers in this field – Peter Higgs (working alone), the Belgian theoretical physicists François Englert and Robert Brout, working in collaboration, and Kibble, a physicist at Imperial College, London, working with the Americans Gerald Gulanik and Carl Hagen.
Englert and Brout published first, in 1964, devising the equations of a mass-giving field that would pervade the cosmos and be consistent with relativity. Shortly afterwards Higgs made the same proposal, and pointed out that ripples in this field would take the form of a new particle. Later that same year, Kibble and his collaborators came to the same conclusion in a paper considered to be the most thorough and complete of the three.
Under the rules of the Nobel Prize no more than three living scientists can be given the award. Higgs and Englert were selected because they were the first two to publish (Brout’s death in 2011 meant he was ineligible). Higgs, however, pointed out that Kibble had gone on to perform further valuable independent work, notably publishing a key paper in 1967 in which he showed that the Higgs mechanism can be extended to explain how elementary particles known as the W and Z bosons have mass, whereas photons, which make up light, have none – in other words how the mass-giving mechanism works in the real world.
But the modest Kibble was always dubious about the idea of awards for his work. His son Robert recalled in an interview that his father had seemed excited about only one award he had received – the Nesta award for creative mentoring in science, which he won in 2005. “Our paper was unquestionably the last of the three,” Kibble said, after hearing about the Nobel, “and it is therefore no surprise that the Swedish Academy felt unable to include us, constrained as they are by a selfimposed rule that the prize cannot be shared by more than three people.”
Thomas Walter Bannerman Kibble was born on December 23 1932 in Madras, where his father, Professor Walter Kibble, taught Mathematics and Statistics at the Madras Christian College in Tambaram. His maternal grandparents were Helen Bannerman, best known as the author of Little
Black Sambo, and William Bannerman, an officer in the Indian Medical Service.
Tom Kibble was educated at Doveton Corrie School in Madras, India, then at Melville College, Edinburgh and Edinburgh University, where he read Mathematics and Mathematical Physics. He arrived at Imperial College in 1959, joining the research group founded by Professor Abdus Salam.
Over the course of his career Kibble made many other important contributions to theoretical physics, including how features known as “cosmic strings” might have formed in the early universe. Although these “strings” have not yet been observed by physicists, similar effects have been recreated in laboratories, where their formation is explained by an effect known as “Kibble-Zurek scaling”, named after Kibble and Wojciech Zurek.
In 1970 Kibble became Professor of Theoretical Physics at Imperial, and held the position of head of the Department of Physics from 1983 to 1991. In 2008 the paper he wrote with his two colleagues in 1964 was selected as one of the most important papers of the last 50 years by the journal Physical Review Letters. In 2009 he was jointly awarded the 2010 JJ Sakurai Prize for Theoretical Particle Physics – one of the most important international prizes in physics. In 2013 he was appointed one of four new honorary fellows of the Institute of Physics, and received the Dirac Medal, which is given to scientists who have made significant contributions to theoretical physics.
Kibble, who listed “destructive gardening” among his recreations, was in Central Hall Westminster in July 2012, when scientists at Cern announced the Large Hadron Collider had discovered a particle commensurate with the long-awaited Higgs boson. “It felt quite surreal, actually,” he said later.
Kibble was elected a Fellow of the Royal Society in 1980, served as its vice-president in 1988-89 and won its Royal Medal in 2012. He was appointed CBE in 1998 and knighted in 2014.
In 1957 he married Anne Allan, who died in 2005. He is survived by their son and two daughters. Sir Tom Kibble, born December 23 1932, died June 2 2016