Photon mass and Heaviside force

Some new observable consequences of the introduction into Maxwell's theory of light of a non-zero photon mass and associated O(3) gauge invariance are discussed, which apparently contradict its Copenhaguen interpretation. In this model light, in free space, is built with real fields and photons whic h both carry real energy momentum distributions. This implies that physical 'vacuum' can contribute to an action equal reaction real process, mediated by the Heaviside force, and opens new ways to interpret recently observed phenomena, such as new terms in the Lorentz Force, now predicted by the Cau sal Interpretation of Quantum Mechanics. (C) 2000 Published by Elsevier Sci ence B.V.