US physicists (from left to right) John Bardeen (1908-1991), William Shockley (1910-1989), Charles Townes (1915-2015) and Walter Houser Brattain (1902-1987). Brattain, Bardeen and Shockley are best known for inventing the transistor and shared the 1956 Nobel Prize in Physics for their invention. Transistors are solid state switches found in nearly every electronic component today. Townes is best known for his investigations into electrical and magnetic interactions within molecules, which led to his design of the maser, an intense source of microwaves and precursor to the laser. This work earned him a share of the 1964 Nobel Prize in Physics. Photographed in February 1967 at a retirement ceremony at Bell Laboratories for Walter Houser Brattain.