On low-energy quantum gravity induced effects on the propagation of light

Present models describing the interaction of quantum Maxwell and gravitational fields predict a breakdown of Lorentz invariance and a nonstandard dispersion relation in the semiclassical approximation. Comparison with observational data, however, does not support their predictions. In this work we introduce a different set of ab initio assumptions in the canonical approach, namely that the homogeneous Maxwell equations are valid in the semiclassical approximation, and find that the resulting field equations are Lorentz invariant in the semiclassical limit. We also include a phenomenological analysis of possible effects on the propagation of light, and their dependence on energy, in a cosmological context.