John Polkinghorne, who held the Chair of Mathematical Physics in DAMTP from 1968 until 1979, has died.
John made significant contributions to several areas of elementary particle theory, including the analytic structure of the S-matrix in quantum field theory, the covariant parton model and proton scattering at high momentum transfer. His work on the first topic provided the theoretical foundations of the bootstrap approach to the strong interactions. This seeks to constrain the scattering matrix of elementary particles by directly imposing properties such as unitarity, causality and crossing symmetry which in turn follow from the basic principles of quantum mechanics and relativity. Importantly, it does not rely on a specific dynamical model but rather seeks a unique or minimal solution of these consistency conditions.
With Richard Eden, Peter Landshoff and David Olive he authored "The Analytic S-matrix" (1966), which remains a crucial text on this approach and has enjoyed very many citations in recent times. Although the bootstrap fell out of favour in phenomenological particle physics with the advent of the Standard Model, it has remained highly influential in mathematical physics where similar ideas were applied with great success to integrable field theories in two dimensions. The S-matrix bootstrap was instrumental to the development of string theory and, in recent years, has also been revived in the development of new methods for calculating QCD scattering amplitudes and exploring the space of possible S-Matrices in two and higher dimensions.
John was a founding member and head of the DAMTP High Energy Physics group.
During his time in the department he supervised many outstanding PhD students who, along with many other members of the DAMTP group at that time, went on to make significant contributions to particle physics. His PhD students include several DAMTP faculty (emeritus): Ian Drummond, Peter Goddard and Peter Landshoff, as well as James Stirling (Durham, Cavendish, Imperial).
John had a friendly and outgoing personality, and offered encouragement to all the PhD students in the group, not just those working in his own research areas. He also initiated the practice of group members meeting each day for coffee at 11 am in the HEP common room on the first floor of the old DAMTP building in Silver Street. This evolved into the current successful morning coffee gatherings of the HEP and GR groups in the Potter Room at CMS (sadly interrupted by the Covid lockdowns).
John was elected as a Fellow of the Royal Society in 1974. He chose to resign from his professorship in 1979 to train for ordination and became an Anglican priest in 1982. After serving as a parish priest, he became Dean of Trinity Hall in 1986 and then President of Queens' College in 1986 until 1996. He was knighted in 1997 although the title Sir was not used as he was a priest. He wrote many books on science and theology and was awarded the Templeton prize in 2002. He remained active in retirement and continued to be an influential thinker on the relationship between science and religion.