2003–2004
This paper exposes an unjustified hidden assumption in a Letter in Physics Letters A which purports to show that feasible increases in precisions of certain gravitational experiments can settle the question whether leptons generate gravity, specifically that if the experimental outcomes persist under these increases, then the possibility that leptons do not generate gravity is made less likely. I show that increased precision in those experiments with the same outcomes is consistent with the possibility that leptons do not generate gravity, thus that, contrary to an assumption Einstein made in his 1916 paper setting out the general theory of relativity, inertial–passive mass (and by extension energy) is not equivalent to active gravitational mass. (My assertion in Footnote 3 that any gravity produced by an electromagnetic field interior to a material body would not be detectable externally probably needs qualifying, but not to a degree that would mandate a substantial alteration of the conclusion of my argument.)