Abstract
A review is presented of the theoretical and experimental work on rotating superconductors. By measuring the determination London field, BL=-(2m*c/e*)ω, with respect to the flux quantum, hc/e*, a precise of h/me is possible. Using this method, several experiments have obtained ever more with the most recent Stanford data at an accuracy of 20 ppm. There are no relativistic corrections to e* which is exactly 2e, but m*=2me only in the non-relativistic limit. Various relativistic corrections to m* lead to an observable mass m' which is smaller than 2me by about 10 ppm. Currently there is not satisfactory agreement between theory and experiment.