Smoot, George Fitzgerald, 3d (smōt) [key], 1945–, American astrophysicist, b. Jacksonville, Fl., Ph.D. Massachusetts Institute of Technology 1970. Smoot has been a professor at the Univ. of California, Berkeley since 1971. He and John Mather shared the 2006 Nobel Prize in Physics for their discovery and characterization of small temperature variations in the cosmic microwave background radiation that fills space. Made with the assistance of NASA's Cosmic Background Explorer (COBE) satellite, their measurements provided support for the big-bang theory of the birth of the universe (see cosmology), shedding new light on the origin of galaxies and stars. Smoot, who oversaw one of COBE's instruments, had the main responsibility for measuring the variations. Since COBE, he has continued to work on the microwave background radiation.