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> Magnets can also levitate over other magnets Earnshaw's theorem describes why a free-floating (paramagnetic) magnet cannot levitate over another such magnet.
by eesmith 3y ago
> Magnets can also levitate over other magnets
Earnshaw's theorem describes why a free-floating (paramagnetic) magnet cannot levitate over another such magnet. There must be at least one stable axis which is not from a magnet. See https://en.wikipedia.org/wiki/Earnshaw%27s_theorem https://en.wikipedia.org/wiki/Earnshaw%27s_theorem
> The magnet will induce a current in the superconductor
That's a different sort of levitation. See https://en.wikipedia.org/wiki/Electrodynamic_suspension https://en.wikipedia.org/wiki/Electrodynamic_suspension . We know it's not the same because you can see a magnet floating above a superconductor even though there's no motion.
The relevant reason is https://en.wikipedia.org/wiki/Superdiamagnetism https://en.wikipedia.org/wiki/Superdiamagnetism .
] Superconducting magnetic levitation is due to superdiamagnetism, which repels a permanent magnet which approaches the superconductor, and flux pinning, which prevents the magnet floating away.
] Superdiamagnetism is a feature of superconductivity.
- it_citizen 3y agoSo does that mean the video would exclude honest mistakes from the researchers? Either it is indeed a superconductor at room temperature or the makers of video actively faked the result.
- eesmith 3y agoI'll quote from the linked-to page: > In both of these magnetic repulsion videos, keep in mind that magnetic repulsion and/or levitation are not, by themselves, probative of superconductivity: a diamagnetic material such as pyrolytic graphite [16], can be made to levitate [19] in a magnetic field without being superconductive. See https://en.wikipedia.org/wiki/Magnetic_levitation#Diamagnetic_levitation https://en.wikipedia.org/wiki/Magnetic_levitation#Diamagneti... .