Recent developments in physics and astrophysics lead us to introduce a new tired-light mechanism involving an interaction between a massive photon and Dirac's vacuum particles.
Tired-light mechanisms appeared in the literature as early as the late twenties, when Zwicky (1929), disturbed by the large values of the apparent recession velocities of galaxies, conceived a mechanism whereby photons could lose energy through an interaction with the medium located between the source and the observer. Rather than enter into a detailed historical review of these attempts, we will simply remind the reader that we have suggested other such mechanisms, beginning in 1971. The first idea we put forward (following an original idea by Finlay-Freundlich, 1953-1954, with the approval of Max Born, 1954 a and b) was a photon-photon interaction. This mechanism (Pecker, 1974) was difficult to accept, and we looked instead for possible interactions between the photon and some massive pseudoscalar boson.
