Some “tired light” theorists have suggested that the reason light redshifts over distance is due, not to expansion, but to light slowing down as it travels from a distant source to an observer on earth. Although I have previously agreed in this blog with the non expanding model of the universe, unfortunately I have to find fault with the suggested cause of the observed Hubble redshift being due to light losing speed over distance.
The problem with a reducing speed of c over distance is that it would result in no observed redshifting of light! Contrary to the misconceptions made by authors in Various published papers. The reason for this is simple. If light waves reduced speed over distance then they would have to be be travelling at a slower speed then any light waves later emitted by the same source. The obvious conclusion of this model is that: Any wavefronts emitted by a source would always be slowly “catching up” with those wavefronts already emitted by the source at an earlier time. And the distance between successive wavefronts emitted would always have to decrease to accommodate the different speeds between each successive wavefront.
Taking this into account it becomes clear that even though if the speed of the wave slows, because the distance between wavefronts also diminishes...the observed frequency would still remain the same over any distance. In other words the observed frequency of light would not decay over great cosmological distances in any model where light speed is asssumed to decrease over distance. And as we know this conclusion is ruled out by the observed Hubble redshift
So my conclusion is that although yes I agree with the non expanding model of a universe, I don’t believe a slowing of light speed over distance can explain the observed decay of frequency over distance as observed in cosmological redshift.
And here is another interesting piece from the historical record quoted below. Looks like in 1929 Hubble knew “expansion” was not real. He just couldn’t attribute it to a failure of Einsteins photon model. Because Albert was just too famous to challenge. Seeing as Albert had just won the Nobel prize for saying that light does *not* lose energy/frequency over distance!
“Hubble concluded that his observed log N(m) distribution showed a large departure from Euclidean geometry, provided that the effect of redshifts on the apparent magnitudes was calculated as if the redshifts were due to a real expansion. A different correction is required if no motion exists, the redshifts then being due to an unknown cause. Hubble believed that his count data gave a more reasonable result concerning spatial curvature if the redshift correction was made assuming no recession. To the very end of his writings he maintained this position, favouring (or at the very least keeping open) the model where no true expansion exists, and therefore that the redshift "represents a hitherto unrecognized principle of nature". This viewpoint is emphasized (a) in The Realm of the Nebulae, (b) in his reply (Hubble 1937a) to the criticisms of the 1936 papers by Eddington and by McVittie, and (c) in his 1937 Rhodes Lectures published as The Observational Approach to Cosmology (Hubble 1937b). It also persists in his last published scientific paper which is an account of his Darwin Lecture (Hubble 1953).”
https://apod.nasa.gov/diamond_jubilee/1996/sandage_hubble.html
