In one minute

Martin Tajmar and Clovis de Matos quantise an extended canonical momentum that includes gravitational drag, and apply it to rotating ring-shaped superconductors and superfluids. The starting point is the Barnett effect, in which rotation magnetises a material, together with its gravitational analogue in weak-field general relativity. Measurements of magnetic flux in rotating superconductors disagree with predictions made without a gravitomagnetic term, and the authors ask how much of that gap the gravitomagnetic term explains. For rotating neutral superfluids, the drag effects implied by the superconductor data would still sit within current experimental noise. They propose measuring the torque such a field would exert on a spinning gyroscope, an experiment not yet done.

Gravitomagnetic field of a rotating superconductor and of a rotating superfluid