It looks like something out of a magic show, where the magician is able to defy gravity and float or levitate an object in midair with no apparent explanation. Check out this really cool video which is not a Vegas show, but an example of something called quantum levitation:
It’s not magic at all, but a very cool demonstration from the Association of Science-Technology Centers. It’s a demo from Tel-Aviv University on what happens when a superconductor gets trapped in a magnetic field. What you’re witnessing is something similar to the Meissner Effect.
A disk of very thin sapphire, coated by a material called yttrium barium copper oxide (YBa2Cu3O7-x, to be exact) gets thrown into a bath of liquid nitrogen to bring it to negative 300 degrees Fahrenheit. This creates a superconductor, or an object that conducts electricity without resistance and no energy loss. (I wish my air conditioner could have pulled that off this summer).
A row of magnets is added, and the disc seems to float or be trapped by the magnetic field. The combination of magnetism and superconductivity create the levitation. According to the university’s website, the two fields "don’t like each other." The two fields repel each other, much like putting the opposite ends of a magnet together.
In this case, however, some of the magnetic field does penetrate though and creates something called a flux tube. These tubes move, and the superconductor tries to stop that so the conductor looks as if it is locked in midair.
Don't plan on jumping on the "quantum levitation train" to shorten your daily commute any time soon. Until scientists can figure out a way to have a superconductor at a temperature other than negative 300, the idea is not yet practical. Maybe someday... Stay tuned.