Willis Eugene Lamb Jr.
Lamb, Willis Eugene, Jr. (1913-) is an American atomic physicist whose research into the atomic structure of hydrogen led to his discovery that energy levels of hydrogen fluctuated slightly. For his discovery, called the Lamb shift, he was awarded the 1955 Nobel Prize in physics, shared with German-born American physicist Polykarp Kusch.
A native Californian, Lamb received his B.S. degree in chemistry in 1934 from the University of California at Berkeley (UCB). He continued his graduate studies in physics there under physicist J. Robert Oppenheimer, focusing on the electromagnetic properties of nuclear particles, and received his Ph.D. degree in 1938. From 1938 through 1951, he was a faculty member at Columbia University and, from 1943 on, a research scientist at Columbia's Radiation Laboratory. After leaving Columbia, Lamb taught at Stanford, Harvard, Oxford, and Yale universities and the University of Arizona.
Lamb's most important discovery upset theories of atomic structure that had been accepted since the 1920's. British physicist Paul Adrien Maurice Dirac had described energy levels of the hydrogen atom. Dirac predicted that two levels of hydrogen, one stable and one metastable —halfway between stable and excited—were distinct states but had the same level of energy. Lamb was able to analyze the hyperfine structure of the hydrogen atom spectrum. He exposed a beam of metastable hydrogen to microwave radiation in a magnetic field. Some of the atoms absorbed radiation and some did not. His experiments established that the energy of the two levels was slightly different, a change called the Lamb shift. This discovery led to new discoveries in the area of particle interactions and radiation and to an entirely new way of viewing the relationship between energy and matter.