On the electromagnetic waves propagation in the isotropic universe

摘要

We present a critical analysis concerning the electromagnetic waves propagation on a curved space-time and the correct applicability of the equivalence principle to this phenomenon. In particular we discuss this phenomenon with respect to the Universe background, by showing how any physical wavelength (indeed only those much less than the radius of curvature) could, in principle, freely propagate arbitrarily close to the initial Big-Bang. It is followed by a discussion on the real meaning of the horizons paradox solution, based on extending the result of the classical analysis to the wavelengths of photons present in the primordial thermal bath.