The chunky-style video lends a homespun appearance to the relatively high tech phenomenon of a persistent electric current flowing on the surface of a superconductor, acting to exclude the magnetic field of the magnet floating above it.
Superconductivity is an electrical resistance of exactly zero, which occurs in certain materials below their normal temperature. Unlike the more familiar conductivity of copper, the resistance of superconductors drops to zero abruptly when the material is cooled below its critical temperature.
It’s called “super” because an electric current flowing in a loop of superconducting wire can persist indefinitely with no power source, whereas the conductivity of everyday metal wiring requires a power source. This sounds like a great way to transmit energy until we realize that this effect occurs at extremely low temperatures that are expensive and impractical to implement in normal Earth environments.
In the 1980s, so-called “high-temperature superconductors,” like the substance in this clip were discovered that produced this effect at a relatively “high” temperature of roughly -300ï¿½F. Till them, most superconducting materials and to be chilled at much lower temperatures in order to behave like superconductors.
Several copper-ion ceramics have since been discovered with this superconductive property, which remains one of the major outstanding challenges of theoretical condensed matter physics to fully explain. Although mysterious, what is known about superconductors has several commercial applications, such as in the nanotechnology-based detectors of chemical substances in the air that are in the machines that your baggage has to go through at airports…