The death of Sir William McCrea, at the age of 94, marks the end of an era in British astrophysics. His research spanned many areas, including stellar atmospheres, accretion of gas by single and binary stars, and the formation of stars and of the solar system.
But his most significant work was in the area of relativity and cosmology. He had immense insight into Einstein's theories of relativity, and a deep philosophical interest in cosmology and its problems.
Sir William McCrea was born in Dublin but brought up in Chesterfield, Derbyshire, where his parents moved in 1907.
After studying mathematics at Cambridge, he started research with R.H. Fowler in 1926. In 1928 and 1929 he wrote a series of papers on the atmosphere of the sun. These were the first accurate models of the atmosphere of a star.
In 1930 he moved to a lectureship at Edinburgh, and in 1932 to a readership at Imperial College, London, where he stayed until 1936. His most famous paper of this period was his 1934 work, with E.A. Milne, on Newtonian cosmology, showing that the expanding universe models of general relativity could equally well be derived within a Newtonian framework.
In 1934 Sir William moved to a chair at Queen's University Belfast, where he stayed until 1944. For the last three years of the war he was part of an operational research group in the Admiralty. In 1944 he took over as professor of mathematics and head of department at Royal Holloway College, where he stayed until 1966.
Sir William McCrea was knighted in 1985. His wife, Marian, died in 1995; they had two daughters and a son.