John F. Allen

Who was John F. Allen?

John Frank 'Jack' Allen, FRS 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 elected as a fellow of the Royal Society in 1949.

Born in Winnipeg, he was also known as Jack Allen. Allen was professor of physics at the University of St Andrews, 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 which Allen discovered in 1938 with the help of a pocket flashlight. Over a ten-year period Allen made a movie of the various two-fluid phenomena exhibited by liquid helium-4. The photography of these effects was a real challenge, because liquid helium-4 is essentially transparent. This unique colour movie is one of Allen's great legacies to physics. His was an early use of moving images to documents experiments and inform students and the general public.