  `Ether-drift' experiments have played a crucial role for the origin of
relativity. Though, a recent re-analysis shows that those original measurements
where light was still propagating in gaseous systems, differently from the
modern experiments in vacuum and in solid dielectrics, indicate a small
universal anisotropy which is naturally interpreted in terms of a non-local
thermal gradient. We argue that this could possibly be the effect, on weakly
bound gaseous matter, of the temperature gradient due to the Earth's motion
within the Cosmic Background Radiation (CBR). Therefore, a check with modern
laser interferometers is needed to reproduce the conditions of those early
measurements with today's much greater accuracy. We emphasize that an
unambiguous confirmation of our interpretation would have far reaching
consequences. For instance, it would also imply that all physical systems on
the moving Earth are exposed to a tiny energy flow, an effect that, in
principle, could induce forms of self-organization in matter.
