Do leptons generate gravity? First laboratory constraints obtained from some /G experiments and possibility of a new decisive constraint

Abstract

The equivalence of the active and passive gravitational masses has been tested in the laboratory to an accuracy of about 5 parts in 105. However, this level of sensitivity is not enough to answer the important question whether leptons generate gravity. We point out that some of the contemporary experiments aimed at re-determining the Newtonian gravitational constant, G, have reached the level of sensitivity required to provide the first meaningful result from a direct experiment on this important issue. Stronger constraints on the hypothesis that leptons do not generate gravity could be more decisively provided by still other G experiments if their aimed sensitivities are maintained in experiments with different sets of source masses.