This photograph illustrates the the Meissner Effect - the expulsion of magnetic flux from superconductors. The three magnets and small metal triangle levitate over a dish filled with ytrium-barium-copper oxide. Superconducting ceramics, discovered in 1986, lose all their electrical resistance when cooled below a certain threshold temperature. Superconductors lose all of their electrical resistance when cooled below a certain threshold temperature. The photograph shows a metal triangle supporting three small magnets floating freely above a nitrogen-cooled bed of numerous pellets of the superconducting ceramic. Photographed in 1987.