Interaction of a photon with a gravitational field

IT is usual to analyse the behaviour of photons in gravitational fields as if they were point particles which travel along geodesics. But by taking into account the finite spatial extent of the photon I show that it could interact with the transverse gradient of the gravitational field to give a deflection additional to the well known gravitational deflection of General Relativity. I postulate that this deflection, even though it is extremely small, could be the basis for a much more important effect in which the photon can decay into three photons (or possibly (E. H. Derrick, personal communication) several photons with one or more gravitons). If such a mechanism is possible it would appear as a decrease in photon energy and could be of astrophysical importance in explaining many of the anomalous redshifts that have been observed 1,2 .