Evan James Williams

Evan James Williams FRS (8 June 1903 – 29 September 1945) was a Welsh experimental physicist who worked in a number of fields with some of the most notable physicists of his day, including Patrick Blackett, Lawrence Bragg, Ernest Rutherford and Niels Bohr.

Williams earned a degree at Swansea University, doctorates at Manchester and Cambridge universities and a professorship at Aberystwyth University. He was highly regarded by his colleagues, and made a Fellow of the Royal Society in 1939.

During World War 2 he worked with Blackett to devise ways of countering the devastation of shipping by German submarines.

He died of cancer in 1945 at the age of 42. Blackett broadcast a talk on Williams on BBC radio in 1949.

Early life Williams was born in the Ceredigion village of Cwmsychbant to stonemason James and Elizabeth (née Lloyd) Williams. He attended Llanwenog Primary School, then Llandysul School, where he was a close friend of Evan Tom Davies and, like Davies, excelled in mathematics. From there Williams, at the age of 16, won a £55 scholarship to Swansea University where he studied physics and attained a first-class honours degree in 1923.

Character Williams was stocky and strong, with blue eyes, brown hair and a broad grin; he was gregarious, passionate about cricket, and enjoyed practical jokes. He was a volatile but stimulating companion, and could "argue a case of sheer unreason with devastating logic"; he was a "wild driver with a complete disregard of the laws of dynamics" according to Blackett. "His love for his native Wales was profound."

In 1934 and 1935 he collaborated with W.L. Bragg on a theory of the effect of thermal agitation on the atomic arrangement in alloys. The resulting mean-field theory is called the Bragg-Williams approximation and is useful for solving many problems in statistical physics.

In 1938 Williams was appointed Chair of Physics at the University College of Wales in Aberystwyth and continued his experiments with sub-atomic particles using a cloud chamber. He was elected a Fellow of the Royal Society in March 1939. In the same month he gave a talk on BBC Radio: "The Atomic World".

Williams was the first person who experimentally detected muon decay and managed to photograph it. Williams was director of research from 1941 to 1942, scientific adviser to the Navy on methods of combating submarines from 1943 to 1944, then assistant director of research in the Navy from 1944 to 1945.

Williams was diagnosed with bowel cancer who also broadcast a radio appreciation of Williams in 1949, in which he said:

In 1971 John Tysul Jones published a collection of articles about Williams.

Legacy In his 1949 BBC radio broadcast, Patrick Blackett said: