The principle behind quantum levitation is called the Meissner effect: a material will expel magnetic fields from its interior if it becomes a superconductor. Almog takes advantage of this effect by coating ultra-thin sapphire wafers with yttrium barium copper oxide, a material that becomes superconductive when cooled to -301°F (thus the liquid nitrogen dunk tanks). He then places the cooled discs over a magnet, allowing everyone to see just how deep the animosity between superconductors and magnetic fields runs. The discs do a valiant job of expelling most of the field, though tiny gaps in the coating allow some magnetism to seep in. These leaks act like pins, trapping the disc about an inch above the surface, hovering until it warms up enough to lose its superconductivity. The disc hovers at a standstill or, if lightly pushed, will assume a circular orbit, liquid nitrogen trailing it like tail of a comet.