of Illinois at Urbana-Champaign as a professor of electrical
engineering and physics. Working there in collaboration
with Cooper and Schrieffer, he agonized over
the theoretical aspects of superconductivity. Working
mostly with little more than paper and pencils and examining
closely all of the most significant theories of superconductivity,
he and his colleagues unlocked the secret
of the phenomenon, which is generally referred to as the
BCS (Bardeen-Cooper-Schrieffer) theory. The method
Bardeen, Cooper, and Schrieffer employed in dealing
with the theoretical problems posed by their investigations
provided a method for dealing with other physical
problems. Their collaboration applied directly, for example,
to understanding elementary particle theory.
From 1959 until his retirement in 1975, Bardeen
taught at the Center for Advanced Study at the University
of Illinois. He died of heart failure in Boston on January
30, 1991.