Word: bcs
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Dates: during 1980-1989
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While scientists know the chemical composition of the new class of superconductors, they are less certain about how they work. True, a theory exists that explains low-temperature superconductivity. It is known as BCS, from the initials of Author John Bardeen and his colleagues Leon Cooper and Robert Schrieffer, who shared the 1972 Nobel Prize for Physics for their effort. But BCS may not apply to the strange goings-on at higher temperatures...
...even the best of ordinary conductors have some resistance to the flow of electrical current. The reason: as current passes through, some of the electrons collide with other electrons, thus dissipating their energy in the form of heat. According to the BCS theory, these collisions are avoided in superconductivity. "What causes a material to become superconducting is a phase change,"* explains Bardeen, now a professor emeritus at the University of Illinois. "You can think of it as electrons condensing into a new state." That state involves the pairing of electrons and a kind of group discipline...
While the BCS theory works well near absolute zero, some physicists think it will have to be modified or even scrapped as an explanation for the behavior of higher-temperature superconductors. According to Bardeen, his theory can explain superconductivity up to around 40 K. But at 90 K, he says, "I think it's highly unlikely. We no doubt are going to need a new mechanism." In fact, says Schrieffer, "superconductivity may turn out to have as many causes as the common cold...