Does a possible laboratory observation of a frequency anisotropy of light result from a non-zero photon mass m?

Abstract

Assuming a priori the existence of a non-zero photon rest-mass m_γ>0 and justifying this assumption, we can predict the existence of an anisotropy in velocity and frequency of light in the direction of the apex of the 3 K background cosmic radiation field. Since this frequency shift can now be tested in the laboratory, it is important to improve the precision of these measurements in order to check our predictions. Its possible confirmation implies indeed the definition of an absolute evolution parameter in the rest frame Σ₀ of this 3 K background microwave radiation.