Narlikar, J. V.Pecker, J. C.Vigier, J. P.2012-03-082012-03-081991-04-08http://hdl.handle.net/11007/915Assuming a priori the existence of a non-zero photon rest-mass m1>0 and justifying this assumption, we can predict the exisence of an anisotropy in velocity and frequency of light in the direction ofthe apex ofthe 3 K background cosmic radiation field. Since this frequency shift can now be tested in the laboratory, it is important to improve the precision ofthese 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.enNon-zero photonCosmic radiation fieldMicrowave radiationGeneral relativityIsotropy of light velocityRest-mass of photonsArticle