KINETIC-ENERGY AND THE EQUIVALENCE PRINCIPLE

According to the general theory of relativity, kinetic energy contribu tes to gravitational mass. Surprisingly, the observational evidence fo r this prediction does not seem to be discussed in the literature. I r eanalyze existing experimental data to test the equivalence principle for the kinetic energy of atomic electrons, and show that fairly stron g limits on possible violations can be obtained. I discuss the relatio nship of this result to the occasional claim that ''light falls with t wice the acceleration of ordinary matter.'' (C) 1998 American Associat ion of Physics Teachers.