Sir William Hunter McCrea, mathematician, physicist and astronomer, 1904-1999

William Hunter McCrea was born on 13 December 1904 in Dublin but moved to Chesterfield, Derbyshire before he was three. Here he was educated at the Central (elementary) School and the Grammar School, from which he won an entrance scholarship in Mathematics to Trinity College, Cambridge. He read for the Mathematical Tripos, becoming a Wrangler 1926, and after graduating began research with R.H. Fowler.

Recognition came early with a Cambridge University Rayleigh Prize, a Trinity College Rouse Ball Senior Studentship, a Sheepshanks Exhibition and an Isaac Newton Studentship. After spending the year 1928-1929 at Göttingen University he moved to a succession of academic appointments: Lecturer in the Mathematics Department at Edinburgh University (headed by E.T. Whittaker) in 1930, Reader at Imperial College London in 1932 and Professor of Mathematics at Queen's University Belfast in 1936. In 1943 he was given leave from Belfast to undertake Operational Research in the Admiralty in the team led by P.M.S. Blackett and in 1944 he was appointed Professor of Mathematics at Royal Holloway University of London, an appointment he took up at the end of the war. McCrea remained at Royal Holloway until 1966 when he took up his last appointment as Science Research Council supported Research Professor of Theoretical Astronomy at the recently established Sussex University. McCrea and University Professor R.J. Tayler, with the support of the Astronomer Royal R.v.d.R. Woolley and other senior Royal Greenwich Observatory staff, effectively put Sussex on the world astronomy map.

McCrea's research covered many areas of mathematics, physics and astronomy, but he is probably best known for his work on relativity and cosmology. The following brief account of some of his principal interests draws on the obituary by Robert Smith and Leon Mestel in The Observatory Magazine. McCrea was an advocate, along with E.A. Milne, of the use of a Newtonian framework to provide simple derivations of the expanding universe models of general relativity. In the 1950s his interest in relativity led to a contentious dispute with Herbert Dingle on the famous 'twin paradox'. During the same period he was one of the few people to take seriously the steady-state theory developed by H. Bondi, T. Gold and F. Hoyle, showing how to treat the theory within the mathematical framework of general relativity, though he later accepted that the theory was ruled out by observational evidence. He had a particular interest in star formation and developed an innovative (though not widely supported) model for the origin of the solar system. He was the first to make a quantitative study of the rate of formation of hydrogen molecules on the surfaces of dust grains in space, a process crucial to many reactions in interstellar chemistry. He was quick to realise in the 1960s that the newly postulated phenomenon of mass transfer in close binaries could be used to explain the presence of 'blue stragglers' which occupied the extended main sequence of some globular clusters. McCrea wrote some 280 scientific papers and a number of books including Relativity Physics (1935), Analytical Geometry of Three Dimensions (1942) and the less technical Physics of the Sun and Stars (1950). McCrea played a major role in British astronomy.

From 1944 he spent many years on the Admiralty's Board of Visitors of the Royal Greenwich Observatory and on its Science Research Council successor. He was very actively involved in the RGO's Tercentenary celebrations (1675-1975), writing an historical review for the occasion which was published by the HMSO. In 1985 he served on a Science and Engineering Research Council (SERC) Astronomy Working Group (chairman J.F.C. Kingman) which reviewed arrangements for ground-based astronomy. McCrea strongly dissented from the subsequent decision of the SERC (announced March 1986) to move the RGO from Herstmonceux in Sussex. His work for scientific societies was extensive, including, for example, serving on key Royal Society committees with respect to astronomy and space science. However, it was his contribution to the Royal Astronomical Society that was unique, having held all four offices (President, Secretary, Treasurer and Foreign Correspondent), and serving on its Council almost continuously from 1936 to 1980. He was frequently asked to be visiting professor for long or short periods, for example at the University of California, Berkeley in 1956 and 1967 and at the Case Institute of Technology, Cleveland in 1964, and often travelled as an exchange visitor under Royal Society auspices, for example to the USSR in 1960 and 1968, India in 1976 and Egypt in 1981. He was the first British scientist to make an official visit, also under the Royal Society auspices, to Argentina after the Falklands War.

As a great admirer of Georges Lemaitre, he was particularly pleased to be the first occupant of the Georges Lemaitre Chair at the University of Louvain in 1969. In his extensive overseas commitments over many years he was almost an ambassador for British astronomy. His distinction in research and services to astronomy were recognised by many honours and awards including election to the Fellowship of the Royal Society in 1952, the award of the Gold Medal of the Royal Astronomical Society in 1976 and a knighthood in 1985. In 1933 he married Marian Nicol Core who died in 1995. They had one son and two daughters. He died in Lewes, Sussex on 25 April 1999 aged 94.

From the guide to the Papers and correspondence of William Hunter McCrea, Knight, mathematician, physicist and astronomer, 1904-1999, 1890-2004, (Royal Holloway, University of London)