John Bardeen (May 23, 1908 – January 30, 1991) was an American physicist and electrical engineer, who won the Nobel Prize in Physics twice: first in 1956 with William Shockley and Walter Brattain for the invention of the transistor; and again in 1972 with Leon Neil Cooper and John Robert Schrieffer for a fundamental theory of conventional superconductivity known as the BCS theory. In 1990, John Bardeen appeared on LIFE Magazine 's list of "100 Most Influential Americans of the Century Image:Cscr-featured.png