Beneath the west stands of the football stadium at the University of Chicago, a team led by the Italian-born physicist Enrico Fermi initiates the first controlled nuclear fission chain reaction in an "atomic pile" containing uranium and graphite.
The American physicists Richard Feynman & Julian Schwinger, and the Japanese physicist Sin-Itiro Tomonaga develop quantum electro-dynamics (QED), the first complete theory of the interaction of photons and electrons.
The American physicists John Bardeen, (counterclockwise from the top) William Shockley & Walter Brattain invent the transistor, an electronic amplifier made from a small piece of semiconducting material. It is the forerunner of integrated circuits and memory chips.
The German-American physicist Maria Goeppert Mayer & Hans Jensen in Germany, describe the atomic nucleus as made of spherical shells of neutrons and protons. This explains the special stability of certain nuclei.