John F. Allen (physicist)

John "Jack" F. Allen (May 5, 1908 – April 22, 2001) was a Canadian-born physicist. Along with Pyotr Leonidovich Kapitsa and Don Misener, Allen discovered the superfluid phase of matter in 1937 using liquid helium in the Royal Society Mond Laboratory in Cambridge, England. He was also known as Jack Allen. Allen was professor of physics at St Andrews University, Scotland from 1947 to 1978, and then emeritus professor until his death. Allen also used a movie camera to film his experiments, such as the superfluid helium fountain. His was an early use of moving images to documents experiments and inform students and the general public.