I. I. Rabi was an Austrian-born American physicist whose discovery of new ways of measuring the magnetic properties of atoms and molecules paved the way for the development of the maser and the atomic clock and earned him the 1944 Nobel Prize in Physics.

 

Rabi spent most of his working life at Columbia University (1929–1967), where he performed most of his pioneering research in radar and the magnetic moment associated with electron spin in the 1930s and 1940s. His invention, in 1937, of the atomic and molecular beam magnetic resonance method of measuring magnetic properties of atoms, molecules, and atomic nuclei. He originated the idea for the CERN nuclear research center in Geneva (founded 1954).