Superconductivity Superconductivity Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic flux fields occurring in certain materials, called superconductors, when cooled below a characteristic critical temperature. It was discovered by Dutch physicist Heike Kamerlingh Onnes on April 8, 1911, in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum mechanical phenomenon. It is characterized by the Meissner effect, the complete ejection of magnetic field lines from the interior of the superconductor during its transitions into the superconducting state. The occurrence of the Meissner effect indicates that superconductivity cannot be understood simply as the idealization of
Heike John Aachen and earned a doctorate in 1987. In the same year she was selected as one of five West German astronaut candidates for the Spacelab D-2 mission, along with Hans Schlegel, Ulrich Walter, Gerhard Thiele and Renate Brümmer. She served as Cap com during the D-2 mission in 1993, but was never assigned to a spaceflight herself. After retiring as an astronaut, she became a professional pilot for Lufthansa. She is married to astronaut Hans Schlegel. Heike John Heike John (now Heike Walpot; born 19 June 1960) is a retired German swimmer and former astronaut candidate. She won a bronze