Along with Leon Cooper and Robert Schrieffer, John Bardeen won the Nobel prize for physics in 1972. This was the second time Bardeen had received the award. (Image: Science Photo Library)
Read more: “Instant Expert: Superconductors“
Within 50 years of the discovery of superconductivity, an elegant theory was in place that explained all of its effects. Superconductivity was essentially a solved problem. Then, in 1986, one discovery upset everything. Its implications are still unravelling and we are yet to find a theory to account for it. What we really want, however, is a superconductor that operates at room temperature. Might one be within our grasp?
Bardeen, Cooper, Schrieffer
The most important breakthrough in understanding superconductivity near absolute zero came from the work of John Bardeen, Leon Cooper and Robert Schrieffer in 1957. Bardeen (pictured) already had one Nobel prize in physics for his part in the invention of the transistor, and the work on superconductivity would earn him his second, shared with Cooper and Schrieffer.
The ideas they worked on together are now known as BCS theory and provide a description of the superconducting state in terms of interactions between pairs of electrons. Because they have the same negative charge, electrons tend to repel each other, but this can change in certain materials that have a crystal lattice. The lattice vibrates with more or less energy depending on the temperature. When it is very cold, the gentle vibrations can push electrons together, producing a net attractive force that drives them to pair up. BCS theory shows how this tendency to pair up can result in superconductivity. …