Test for relativistic gravitational effects on charged particlesp

Experimental results are presented which provide the first measurement of the effects of a gravitational field on charged particles, equivalent to the red shift for photons. Two Josephson-effect batteries (V≃300 μV) having a vertical separation of 7.2 cm are connected in opposition by superconducting wires. A voltage difference of 2.35×${10}^{\mathrm{-}21}$ V is maintained between these batteries by means of the gravitational red shift. The emf around this loop is, however, measured to be less than 1×${10}^{\mathrm{-}22}$ V, consistent with the predicted invariance of the gravito-electrochemical potential along the wires.