Superconductivity

This very nice lady was giving an excellent demonstration of magnetic levitation, at the Toshiba Science Museum, Kawasaki. Here's what Wikipedia has to say about the subject:

Superconductors may be considered perfect diamagnets, completely expelling magnetic fields due to the Meissner effect. The levitation of the magnet is stabilized due to flux pinning within the superconductor. This principle is exploited by　electrodynamic suspension magnetic levitation trains.　In trains where the weight of the large electromagnet is a major design issue (a very strong magnetic field is required to levitate a massive train) superconductors are sometimes proposed for use for the electromagnet, since they can produce a stronger magnetic field for the same weight.