Cooper, Leon (1930-…), an American theoretical physicist, contributed to the development of the theory of superconductivity (the loss of all electrical resistance by some materials when cooled below a certain temperature). He shared the 1972 Nobel Prize for physics with his American colleagues John Bardeen and John Robert Schrieffer (see Bardeen, John ; Schrieffer, John Robert ).
In the 1950’s, Cooper and his two collaborators developed a theory to explain superconductivity. This theory is usually called the BCS theory from the initials of the three scientists who worked on it–_B_ardeen, _C_ooper, and _S_chrieffer. Cooper later made the unusual move of taking up research in theoretical biology, studying the behavior of the nervous system and developing special types of computer circuits that mimic animal nervous systems.
In an ordinary electrical conductor, the atoms are arranged in a regular pattern called a lattice. Cooper made an important step in understanding superconductivity when he discovered that, at low temperatures, electrons (tiny particles carrying one unit of negative electric charge) could affect each other via the lattice. An electron moving through the lattice distorts it slightly, and the distorted lattice affects other electrons. Cooper found that this interaction could cause an electron, in effect, to attract another, so that the two electrons move together as Cooper pairs through the lattice. Schrieffer made a further advance when he found that at low temperatures all the Cooper pairs in a conductor could move together.
Cooper was born in New York City on Feb. 28, 1930, and received his university education there, gaining his Ph.D. at Columbia University in 1954. After a period at the Institute for Advanced Study, Princeton, New Jersey, he moved to the University of Illinois in Urbana, where he worked with Bardeen and Schrieffer on the theory of superconductivity.
In 1958, he moved to Brown University in Providence, Rhode Island, where he held a succession of professorships. In 1991, he served as the first director of Brown University’s Institute for Brain and Neural Systems Mathematicians, physicists, linguists, and biologists collaborate at the institute to understand the workings of the brains and nervous systems of the higher animals, including human beings. In 1975, he helped found Nestor, Inc., a private company that develops computer software and hardware systems called neural networks, which attempt to mimic the networks of nerve cells in the brain. A neural network is not programmed in the same way as a conventional computer. Instead, it “learns” by example to recognize complex patterns, such as the expression on a face, trends in a stock market, or medical symptoms requiring diagnosis.
