2 ms·

Magnets can also levitate over other magnets, so it's not only possible with superconductors. But it does happen with superconductors. The magnet will induce a

Magnets can also levitate over other magnets, so it's not only possible with superconductors. But it does happen with superconductors. The magnet will induce a current in the superconductor, which creates a magnetic field, which repels the magnet.

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 ago
  So 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 ago
    I'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... .

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 ago
So 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 ago
  I'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... .