Gravity modification by high-temperature superconductors

Abstract

Claims that the weight of test masses can be changed in non-relativistic experiments have been investigated. Amongst the most prominent reports has been a paper by Podkletnov & Nieminen (Physica C 203 441, 1992); more recently, Rounds (Proc. NASA Breakthrough Propulsion Phys. Workshop, Cleveland, 297, 1998) used a simpler experimental arrangement. Both of these experiments measure the gravitational field above YBa2Cu3O7_£ (superconducting below Tc * 93K). Podkletnov & Nieminen specify that the superconductor must be cooled below 70K, magnetically rotated at -5000 rpm, and simultaneously levitated magnetically using two separate frequency excitations; weight changes of ~1% were reported. Rounds specifies less stringent conditions, mainly that the YBCO is cooled to 77K whilst stationary. The Rounds experiment has been repeated virtually exactly, and the Podkletnov experiment has been investigated by reproducing some of the conditions specified. No measurable gravity modification (within ±0.03%) was observed using the subset of the Podkletnov conditions, (but this does not preclude gravity modification arising from the foil specified conditions). The Rounds configuration also has not shown any effects reliably ascribable to gravity modification, although there was unusual thermal behaviour.