Wednesday, August 11, 2010

BCS as Foundation and Inspiration: The Transmutation of Symmetry

This is Frank Wilczek's contribution to a volume on the 50th Anniversary of the BCS theory. It shows clearly the connection and influence of this amazing theory to the rest of theoretical physics.

The influence of BCS theory on the broader discipline of theoretical physics has been no less profound. Two key ideas abstracted from BCS theory, that have been widely transplanted and borne abundant fruit, are pairing and dynamical symmetry breaking. Pairing was an essentially new idea, introduced by Cooper and brought to fruition by BCS. The symmetry breaking aspect was mostly implicit in the original BCS work, and in earlier ideas of Fritz London and Landau-Ginzburg; but the depth and success of the BCS theory seized the imagination the theoretical physics community, and catalyzed an intellectual ferment. The concept of spontaneous symmetry breaking was promptly made explicit, generalized, and put to use by several physicists including Anderson, Josephson, Nambu, and Goldstone. The flexibility and transformative power of these ideas revealed itself gradually, in applications to phenomena that at first sight appear to have little or nothing in common with superconductivity.


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