Paul Adrien Maurice Dirac
1902-1984
British Physicist and Mathematician
Paul Dirac applied Albert Einstein's (1879-19555) theory of special relativity to quantum mechanics, the mathematical framework describing the motion of atomic particles. In doing this he represented the behavior of the electron by means of wave functions. Dirac's wave mechanics predicted the electron spin and the existence of the positron, an "anti-electron" with the same mass but a positive rather than negative charge. In 1933 he shared the Nobel Prize in Physics with the Austrian physicist Erwin Schrödinger (1887-1961).
Dirac was born in Bristol, England, on August 8, 1902. Although his mother was English, his Swiss father, a teacher at his son's school, refused to speak to the boy unless he was addressed in French. Perhaps as a result, Dirac was known for speaking as little as possible. He was good at mathematics, so he decided to studyelectrical engineering, and received his B.Sc. from the University of Bristol in 1921.
Paul Dirac. (Library of Congress. Reproduced with permission.)Dirac never found employment as an engineer. Instead he entered St. John's College of Cambridge University, where he received his Ph.D. in mathematics in 1926. By this time he had already made important contributions to quantum mechanics. He traveled extensively over the next few years, serving as a visiting lecturer at the University of Wisconsin, the University of Michigan, and Princeton University. In 1929 he took a trip around the world, visiting Japan with the German physicist Werner Heisenberg (1901-1976) and traveling through Siberia on his way back to Europe.
In his book The Principles of Quantum Mechanics, published in 1930, Dirac elucidated his transformation theory, a means of understanding the properties of atomic particles using statistical probability distributions. His presentation was solely mathematical, because he believed that to create a mental or visual picture was to "introduce irrelevancies." It was this work for which he was awarded the Nobel Prize.
In 1932, Dirac joined the Cambridge faculty as Lucasian Professor of Mathematics, the prestigious chair once held by Isaac Newton (1642-1727). The same year, Carl D. Anderson (1905-1991) first observed the positron by bombarding aluminum and lead with gamma rays and photographing its tracks in a cloud chamber. This provided experimental confirmation of Dirac's theory. The validation might not have excited Dirac as much as one would expect. He later wrote, "[I]t is more important to have beauty in one's equations than to have them fit experiment."
Dirac married Margit Wigner of Budapest in 1937. When he was 64 years old, he moved to the United States and became professor emeritus at Florida State University in Tallahassee. He died there on October 20, 1984.
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