
%0 Journal Article
%A F Crawford, David 
%T Photons in Curved Space?Time
%J Australian Journal of Physics
%D 1987/06/01
%V 40
%N 3
%P 449-458
%K 
%R https://doi.org/10.1071/PH870449
%U https://www.publish.csiro.au/paper/PH870449 
%X Because photons are described by quantum mechanical wavefunctions that have a nonzero spatial extent it follows that they can be influenced by curved space-time. It is generally assumed that this tidal interaction is far too small to have a significant effect. This paper argues that there is a significant effect that results in an interaction between the photon and the material causing the curved space-time in which the photon loses energy to low energy secondary photons. The energy loss is a function of the space-time curvature and is proportional to distance. The only situation fully considered is that of a photon in curved space-time due to a uniform distribution of matter. Because the energy loss rate is very small it is difficult to observe in the laboratory and therefore its major applications are in astronomy. If the intergalactic density of matter is n hydrogen atoms m - 3, then the predicted value for the 'Hubble' constant (assuming no universal expansion) is 51·68 n1 /2 km s - 1 Mpc - 1. The theory can solve the virial mass discrepancy observed in clusters of galaxies and it makes a definite prediction about their relative magnitudes. Other astronomical applications are considered. 
