Simon, Franz Eugen (1893–1956)

German-born British physicist who developed methods of achieving extremely low temperatures (nearly as low as one millionth of a degree above absolute zero). He experimentally established the validity of the third law of thermodynamics. He was knighted in 1954.

Simon was born in Berlin and studied at several German universities. He became professor at the Technical University in Breslau 1931, but, with the rise to power of the Nazis, emigrated to the UK 1933 and spent the rest of his career at Oxford, as professor from 1945. During World War II, Simon worked on the atomic bomb.

Simon solidified gases by the use of high pressure, and showed that helium could be solidified at a temperature ten times as high as its liquid/gas critical point. He worked on the properties of fluids at high pressure and low temperature, and in 1932 he worked out a cheap and simple method for generating liquid helium.

In the 1930s, Simon developed magnetic cooling to investigate properties of substances below 1K. He then went on to investigate nuclear cooling, showing that the cooling effect is limited by interaction energies.