Comparison of near and Far Field Double-slit Interferometry for Dispersion of the Photon Wavepacket

Extending EM and Quantum Theory suggests the possibility of photon mass, additional terms for Maxwell‘s equations, reality of de Broglie-Bohm causality and the Vigier model of extended charged particles. Experimental tests indicative of these hypotheses can be performed with double-slit interferometry of single visible wavelengths comparing near and far field sources over laboratory and various cosmological distances to observe the possibility of spreading of the photon wavepacket during propagation. These observations could determine whether nonlinearities causing non-dispersivity are associated with Maxwell’s equations. If so, this may be an indirect determination of non-zero restmass photon anisotropy, de Broglie photon piloting and vacuum permittivity reincarnating the Michelson-Morley experiment in terms of a Dirac covariant ether.