John Van Vleck was one of the United States' first theoretical physicists, specializing in problems of chemical physics, magnetism , quantum theory, and spectroscopy. Some of his work has had important practical applications in such devices as the atomic clock, lasers and transistors. He shared the 1977 Nobel Prize for Physics for his "fundamental theoretical investigations of the electronic structure of magnetic and disordered systems."
John Hasbrouck Van Vleck was born in Middletown, Connecticut, on March 13, 1899, into a prosperous family with a history of notable intellectual accomplishments. His paternal grandfather had been a professor of astronomy at Connecticut's Wesleyan College, and his father, Edward Burr Van Vleck, was professor of mathematics at Wesleyan at the time of his son's birth. Van Vleck's mother was the former Hester Lawrence (also given as Laurence) Raymond. It has been noted that his parents' overbearing manner may have been responsible for their only child's shyness as a youngster. When Van Vleck was seven years old his father accepted an appointment at the University of Wisconsin. John attended public schools in Madison and then entered the University of Wisconsin, graduating in 1920 with a bachelor's degree in physics. For his graduate work, Van Vleck chose to attend Harvard University, where his father was serving as visiting professor of mathematics.
Chooses a Career in Theoretical Physics
At Harvard, Van Vleck decided to concentrate on theoretical physics, a field with little tradition in American science at the time. In fact, when he received his doctorate in 1922, his thesis was one of the first, if not actually the first, in America based on a purely theoretical subject--the ionization energy of a particular model of the heliumatom. Upon completing his degree, Van Vleck was invited to stay on at Harvard as an instructor in physics.
In 1923, based largely on his doctoral work, the University of Minnesota offered Van Vleck a job in its physics department; he accepted and remained at Minnesota until 1928. During his tenure there, Van Vleck worked on problems involving the application of quantum mechanical theory to a variety of physical phenomena. His magnum opus during this period was his first book, Quantum Principles and Line Spectra, published in 1926. Though the book came out just as major modifications in quantum theory were being made, much of what he had written remained valid and the book was an unexpected commercial success.
Begins Work on Magnetism
Van Vleck's years at Minnesota were also marked by his first venture into the field for which he is best known, the quantum explanation of magnetic effects. He tried to find a way in which modern developments in quantum theory could be used to explain the various forms of magnetism--efforts which resulted in the publication of The Theory of Electric and Magnetic Susceptibilities in 1932. The work on magnetism was by no means the only topic Van Vleck researched at Minnesota, but it would prove to be the most important, earning him both a share of the 1977 Nobel Prize for physics and the title "father of modern magnetism."
Van Vleck was married to Abigail June Pearson on June 10, 1927. The following year he moved to the University of Wisconsin, where he accepted a post as professor of physics. He was attracted to Wisconsin, in part, by the university's visiting scholars program. Each semester, an outstanding authority in some field was invited to be in residence on the Madison campus. Van Vleck knew that the program would be an excellent way for him to stay in touch with developments in modern physics, a field in which American scientists were woefully deficient. In 1934, Van Vleck was offered an opportunity to return to Harvard, one that he accepted. He remained at Harvard until his retirement in 1969, serving the last eighteen years of his tenure there as Hollis Professor of Mathematical and Natural Philosophy, the oldest endowed science chair in North America.
One of Van Vleck's areas of interest at Harvard was crystal field theory. He again used quantum theory to evaluate the relationship between electron and ion energy levels in bound systems such as crystals. Understanding these relationships is critical in solid-state theories and in their applications in devices such as lasers and semiconducting devices.
At the beginning of World War II, Van Vleck was asked to serve on a committee evaluating the feasibility of building an atomic bomb. That committee's favorable decision eventually led to the creation of the Manhattan Project, under which the world's first nuclear weapons were designed and built. For the majority of the war years, however, Van Vleck worked on the development of radar at the Radio Research Laboratory in Cambridge, Massachusetts.
Van Vleck worked on a host of other problems on his return to Harvard after the war, including nuclear magnetic resonance, molecular spectra, and the cohesive energy of metals. In addition to the Nobel Prize, he was awarded the title of Chevalier in the French Legion of Honor, and was the recipient of the Irving Langmuir Award of the General Electric Foundation in 1965, the National Medal of Science in 1966, and the Lorentz Medal of the Royal Netherlands Academy of Science in 1974, among others. Van Vleck died in Cambridge on October 27, 1980.
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