Superconductors are an incredible scientific discovery and not just because they have the oh-so-nice property of having 0 electrical resistance. They also have the peculiar property of ejecting all magnetic fields from within them, an interesting phenomena considering the duality of electromagnetism. Unfortunately traditional superconductors required extremely low temperatures to exist, usually not far off absolute zero. This made them impractical for the many uses we could think of for them as whilst the lack of resistance would prove a boon for power transmission the ongoing maintenance would prove to be far too costly. However recent materials advancements have given rise to what we call high temperature superconductors which has opened up many new avenues of research.
Don’t let their moniker fool you though, the temperatures that most of these operate at are still well below freezing, however they do become superconducting at temperatures that are achievable using coolants like liquid nitrogen rather than exotic solutions relying on cryogenic fluids like liquid helium. This has lead to a lot of research with these particular kinds of superconductors and interestingly some demonstrations that almost appear like magic when you first see them:
As I mentioned earlier superconductors expel all magnetic fields from within them, however when the superconductor is thin there will be little areas of weakness where the magnetic field can get through. Since the superconductor is trying its darnedest to expel those fields it locks them in those small areas allowing the superconductor to levitate on the field. The locking happens in the direction of the magnetic field which actually allows you to do some very interesting things (as demonstrated in this video). The effect only lasts as long as the cooling however and once that’s gone the levitation effect disappears instantly.
Really hammers home Arthur C. Clarke’s quote: “Any sufficiently advanced technology is indistinguishable from magic.” doesn’t it?