Val Logsdon Fitch Biography (1923-)


Val Logsdon Fitch was born to Fred B. and Frances M. (Logsdon) Fitch on March10, 1923, on a cattle ranch near Merriman, Nebraska, a short distance from the South Dakota border. After an injury to the elder Fitch on the ranch, thefamily moved to nearby Gordon, Nebraska, where Fitch attended public primaryand secondary schools. After graduation, he joined the U.S. Army.

In 1943, Fitch was assigned to the Special Engineering Detachment located inLos Alamos, New Mexico, the research center of the Manhattan Project. In thatassignment, he had contact with some of the world's greatest physicists whowere working on the design of the atomic bomb. Originally interested in chemistry, Fitch changed his career plans to physics as a result of his wartime experiences.

After his discharge, Fitch enrolled in Montreal's McGill University and earned his bachelor of science degree in electrical engineering two years later. He then went to Columbia to begin his doctoral research on the study of mu-mesic atoms under Nobel laureate Leo James Rainwater. Discovered in 1935 by CarlAnderson, the mu-meson is now known to be a type of lepton, a particle similar to the ordinary electron, but more than two hundred times as heavy.

At Columbia, Fitch investigated the possibility of an atomic structure consisting of a nucleus and mu-mesons rather than a nucleus and ordinary electrons.It was already known that such atoms could be manufactured when a mu-meson is captured by an atom and incorporated into its structure. Under the right circumstances, the mu-meson falls to the K energy level of the atom, the energylevel nearest the nucleus. There, it travels in an orbital much closer to the nucleus than does the ordinary electron.

In fact, the size of the mu-meson's K orbital is determined by the size of the nucleus itself. In Fitch's research, he found that the meson travels so closely to the nucleus that it actually passes through the nucleus more than half of the time. The orbital diameter calculated by Fitch allowed him to estimate the size of the lead nucleus used in the experiment, a size that turned out to be much smaller than previously had been estimated.

Fitch's mu-mesic atom studies earned him a Ph.D. in physics in 1954. He thenaccepted a position at Princeton University, where he rose to the rank of professor in 1960. He also became chair of the department in 1976 and, in the same year, was appointed Cyrus Fogg Brackett Professor of Physics. Fitch continued his research on particle physics at Princeton and, in the mid-1960s, became involved in another project with revolutionary consequences.

This undertaking involved a study of the phenomenon known as CP symmetry. Thehistory behind the problem dates to 1956 when Tsung-Dao Lee and Chen Ning Yang announced the hypothesis that parity ("left-handedness" vs. "right-handedness") might not be conserved in certain types of nuclear reactions. Confirmation of that hypothesis by Chien-Shiung Wu and her colleagues at Columbia startled the world of physics. It meant that classical laws of conservation (as of mass, energy, charge, momentum, etc.) might not be inviolate after all.

In 1964, Fitch collaborated with Princeton University researcher James Croninin a series of experiments that addressed that question of CP invariance , although rather indirectly. The experiments were an attempt to understand thedecay scheme of a particle known as the neutral K-meson, K0. As anaccidental by-product of this research, Fitch and Cronin observed a number of reactions (about one in five hundred) in which CP symmetry was violated.

Their discovery was significant because it suggested yet another possible level of invariance, one in which parity, charge conjugation, and time (CPT) areconserved in nuclear changes. Consequently, a violation of time symmetry (time-reversal) would be implied, and with it greater insight into the origins of the universe. The possibility of early universe production of common mattersurpassing anti-matter motivates a large field of research in particle physics. In addition to the 1980 Nobel Prize for physics for this research, Fitchhas also been given the 1968 Research Corporation Award, the 1968 Ernest Orlando Lawrence Award, and the 1976 John Price Wetherill Medal of the Franklin Institute.

Fitch is now a professor emeritus in the Princeton University Physics Department. Married to the former Elise Cunningham in 1949, they had two sons, JohnCraig and Alan Peter. After his first wife's death in 1972, Fitch married a second time, to Daisy Harper Sharp, on August 14, 1976.

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