What the electromagnetic vector potential describes

An explicit physical interpretation of the electromagnetic vector potential is here pointed out—as field momentum available for exchange with kinetic momenta of charged matter. It is shown that the vector potential can be quite as directly measurable, without recourse to only quantum-mechanical effects, as are scalar potential differences and the force fields E, B. This suggests, in keeping with quantum electrodynamics, that the equations for potentials may be regarded as more ’’basic’’ than the Maxwell equations—but only because the potentials most directly represent interaction energy-momenta through which fields and charges become observable.