John Charlton Polkinghorne, 1930-2021

John Charlton Polkinghorne was very successful in two careers: as a theoretical physicist and as a theologian. As a physicist at Cambridge, he was one of the pioneers of applying complex variable theory to the study of properties of scattering amplitudes and contributed to the theory of strong (nuclear) interactions. In addition, he was a successful teacher, with many of his students gaining senior academic positions in universities. A postmaster's son from Weston-super-Mare, he married Ruth Martin, also a mathematics student at Cambridge. They had three children. John surprised many, apart from those who knew him closely, by resigning from his Chair at Cambridge to study for ordination in the Anglican Church. He became an influential theologian devoting much study to the interaction of science and religion. His position might be summed up in a phrase he was fond of, "God holds the Universe in being", which was John's solution to what is called the fine-tuning problem in physics: that the parameters of Nature turn out to be exquisitely adjusted to allow our universe to exist in its richness. John was a formidable administrator, became President of Queens' College, Cambridge, and chaired UK government committees on research ethics.