A pessimist might posit that David Pines' 1955 career move cost him a share of the 1972 Nobel Prize in Physics. But, looking back on a career that spans almost 60 years studying the theory of superconductivity, Pines has no regrets.

Superconductivity is the mysterious quantum state through which certain materials exhibit zero electrical resistance at very low temperatures. Such materials were first discovered in 1911, but the theory describing the phenomenon was not devised until 1957. In the meantime, all the giants of theoretical physics, from Albert Einstein to Werner Heisenberg, tried to come up with a theory. “Everyone wanted to understand this fascinating phenomenon that signalled the emergence of a new quantum state,” says Pines, now a theoretical physicist at Los Alamos National Laboratory in New Mexico and the University of California, Davis.

By 1952, when Pines became a postdoc with John Bardeen at the University of Illinois at Urbana-Champaign, there were hints that superconductivity might result from phonons — discrete quanta, or packets, of vibrational energy in a crystal lattice — generating an attractive force between electrons. Leading physicists scoffed at the idea, believing that such a force would be overwhelmed by Coulomb repulsion — which occurs between two like charges — between electrons. But in 1954, Pines and Bardeen showed that, despite strong Coulomb repulsion, it is possible for phonons to generate an attractive force for some electrons.

This laid the groundwork for Leon Cooper, who replaced Pines as Bardeen's postdoc in 1955, when Pines moved to Princeton University in New Jersey. Cooper, Bardeen and Bardeen's graduate student Bob Schrieffer went on to find a bound state for electrons of opposite spin that attract one another, and discovered the wave function for the superconducting state that results from this attraction. They published the Bardeen-Cooper-Schreiffer (BCS) theory of superconductivity in 1957, which earned them the 1972 Nobel prize.

Although his contribution did not net him a share of the Nobel, Pines relishes the part he played in establishing the theory's foundations. “The BCS paper had a major role in the development of nuclear physics, astrophysics and particle physics,” he says. “It had the same role in the physical sciences that Watson and Crick's DNA paper had in the biological sciences.”

In the mid-1980s, many theorists turned to considering whether superconductivity could occur in the absence of phonons. Superconductivity had been discovered in heavy electron materials such as uranium–platinum 3 (UPt3), and high-temperature superconductivity identified in copper-oxide-based materials. Following these discoveries, Pines, along with other theorists, proposed that the mechanism in these almost antiferromagnetic materials was a magnetic interaction between electrons of opposite spins that could be highly attractive. Pines and his colleagues subsequently explored this mechanism in detail (see page 1177).

A consensus on a theory of high-temperature superconductivity is proving difficult to reach, says Pines, because the explosion in experimental work means that “some theorists view high-temperature superconductivity as a kind of Chinese menu from which you pick favourite experiments to support your theory”. But, he points out, “Science is not like that — you have to explain all the key facts.”