BCS theory

BCS Theory is an attempt to explain superconductivity, the ability of certain materials to conduct electricity without resistance. It proposes that electrons with opposite spin can become paired, forming [Cooper pairs]?. In this process they have slightly less energy than the two electrons would have separately, and this energy gap acts like an insulating layer that stops the interactions at the electron level that lead to what we see as resistance.

It is difficult to make an analogy, as electrons don't behave like objects we see every day. Here is one attempt:

Imagine you have a piece of sponge that you want to push through a pipe, but the sponge is just a little too big. Even if you get the sponge into the pipe it drags on the sides of the pipe too much to move. The sponge is an electron, and the pipe is a piece of wire. Now imagine you could add a substance (an electon) to the sponge that would make it shrink just enough to fit in the pipe, and that this substance coated the sponge with a non-stick coating (the energy gap). Now the sponge will run through the pipe with no resistance.

BCS theory was developed by John Bardeen, [Leon Cooper]?, and [Robert Schrieffer]?, who received the Nobel Prize for Physics in 1972 as a result.