Charles Townes built the first operational maser at Columbia University in 1953, a device that amplifies microwaves through stimulated emission of radiation. Nikolai Basov and Alexander Prokhorov independently developed the same principle in the USSR. The 1964 Nobel Prize in Physics was jointly awarded to Townes, Basov, and Prokhorov in explicit recognition of the simultaneous independent development. The maser principle is the direct basis of the laser, developed in 1960.