Isidor Isaac Rabi was a Galician-born American physicist and Nobel laureate, recognized in 1944 for his discovery of nuclear magnetic resonance, which is used in magnetic resonance imaging. He was also involved in the development of the cavity magnetron, which is used in microwave radar and microwave ovens.
Born into a traditional Jewish family in Rymanów, Galicia, in what was then part of Austria-Hungary, Rabi came to the United States as a baby and was raised in New York's Lower East Side. He entered Cornell University as an electrical engineering student in 1916, but soon switched to chemistry. Later, he became interested in physics. He continued his studies at Columbia University, where he was awarded his doctorate for a thesis on the magnetic susceptibility of certain crystals. In 1927, he headed for Europe, where he met and worked with many of the finest physicists of the time.
In 1929 Rabi returned to the United States, where Columbia offered him a faculty position. In collaboration with Gregory Breit, he developed the Breit-Rabi equation and predicted that the Stern-Gerlach experiment could be modified to confirm the properties of the atomic nucleus. He developed techniques for using nuclear magnetic resonance to discern the magnetic moment and nuclear spin of atoms. This work led to his being awarded the Nobel Prize for Physics in 1944. Nuclear magnetic resonance became an important tool for nuclear physics and chemistry. The subsequent development of magnetic resonance imaging from it has made it important to medicine as well.