Anderson, Philip Warren (1923-2020), was an American theoretical physicist who studied the physical properties of solid and liquid materials. This field of physics is called solid-state physics, or condensed-matter physics (see Solid-state physics ). Anderson carried out fundamental work on theories of the electronic distribution of magnetic materials. He also studied disordered systems, materials in which the atoms are not arranged in definite patterns. His work improved scientists’ understanding of how electric currents flow in noncrystalline materials (those without a regular atomic structure) as well as in superconductors—materials that lose all resistance to the flow of current at low temperatures (see Crystal ; Electronics ; Superconductivity ). In 1977, Anderson was awarded the Nobel Prize for physics, sharing the prize with Sir Nevill Mott of the United Kingdom and John H. Van Vleck of the United States (see Mott, Sir Nevill ; Van Vleck, John Hasbrouck ).
Anderson was born in Indianapolis on Dec. 13, 1923. In 1949, he obtained his Ph.D. in physics from Harvard University in Cambridge, Massachusetts. During World War II (1939-1945), he undertook work on radio and radar aerials. In 1949, Anderson joined Bell Laboratories (then the research department of the Bell Telephone Company) in New Jersey, becoming part of its brilliant group of theoretical physicists. Until that time, physics could deal only with the simplest states of matter. These states included gases—in which the particles do not strongly interact with each other—and crystalline solids, in which the atoms are arranged in a regular, repetitive order like the patterns on wallpaper. In contrast, Anderson’s work dealt with disordered systems—that is, with liquids and with noncrystalline solids (known technically as glasses) in which the atoms are not arranged in definite patterns. In 1958, he discovered a process called Anderson localization, which describes the migration of impurities within a crystal and can trap an electron in a small region in a noncrystalline solid. In 1961, Anderson also devised a theoretical model that described what happened when an impurity is present in a metal, known now as the Anderson model.
In 1961, Anderson visited Cambridge University in England and, from 1967 to 1975, spent most of each academic year there. He worked on problems of superconductivity (the loss of all electrical resistance in certain materials when their temperature is lowered sufficiently) and superfluidity (the loss of all internal friction in a fluid below a certain temperature, so that it can flow with perfect freedom). From 1975 until near the time of his death, he was a professor at Princeton University in Princeton, New Jersey. In 1982, Anderson was awarded the U.S. National Medal of Science, the nation’s highest science award.
In 1963, he wrote Concepts of Solids and, in 1984, Basic Notions of Condensed Matter Physics. Anderson was associated with a number of political causes, including opposition to American involvement in Vietnam and to a proposed high-technology system of defense against missiles called the Strategic Defense Initiative (see Strategic Defense Initiative ). From the mid-1980’s to 2001, he was involved with the Santa Fe Institute, which is devoted to making new connections between disciplines that have previously been separate. Anderson died on March 29, 2020.
