# What was the historical importance of the discovery of high-$T_c$ superconductors?

I remember very well from my (only) class in solid state physics how enthusiastically the professor recounted the discovery of high-$T_c$ superconductors. In one particularly vivid anecdote, he recounted how several hundreds of physicists were trying to jam into some giant lecture hall to be able to witness the announcement (bonus points if someone can recall which event this was!). It really sounded like this was an enormously big deal!

As a stereotypical 'high energy theorist', I never quite understood his excitement. Sure, high $T_c$-superconductors are a very cool thing to discover, but why would they be that big a deal? My best guess is that there used to be very strong reasons to believe such things could not exist (which would make for an interesting story of an accepted theory being proven wrong). If this is the case, an answer would ideally give an in-depth explanation why this result was deemed surprising (i.e. including the physics). In any case, I would love to hear an account of why high-$T_c$ superconductors were such a major breakthrough.

• There seems to be a decent paragraph here (from the start of "Technological applications. . . "), but there's not much there. And I'm guessing you already saw that. – HDE 226868 Dec 9 '14 at 0:46

## 1 Answer

This is what I recall... (I was a high school kid at the time)

There are two aspects. First the new ceramic high Tc superconductors could be cooled with liquid nitrogen - this is much cheaper and easier to obtain (and handle) than liquid helium. This should make superconductor applications more practical. It did, but not as much as many people hoped. A flippant upshot is that you are much more likely to have seen a live demo of the Meissner Effect!

The second - and this was really pushed by the science TV programs - was the hope that these were just a stepping stone, and by adjusting the formula room temperature superconductors were around the corner. This did not happen.

The relative lack of practical applications of N2-cooled superconductors? I'm only an outside observer so someone else probably has more information, but my understanding was that it proved difficult to get reliable high current flows - eg. for long distance power lines. Also creating continuous ceramic power lines is "non-trivial".

• I'll focus point 2 a bit more. The hope was that a theoretical understanding of the higher temperature superconductors would lead to an overall breakthrough in superconductor theory. With a "better" theory we'd then be able to design even more practical superconductors. So the possibility of the development of grand new theories was a big part of the excitement, not just the willy-nilly mixing new formulas to try. – MaxW Jan 26 '17 at 7:26