Indeed, it is an absolutely terrible fit. Note how the line is below almost all of the data points.Looks like a terrible fit. At z=1, the least-action predicted bightness is ~2/5 of a mag low, which is 1.4x too bright. If I remember right, the observed brightness deviation (cf a matter-dominated Universe) is only ~1.5x at z=1.
Just FYI for why tired light models have problems.
1) If you have light change speed, it's like going through a lens. If you go through a lens then there are a ton of effects that we don't see. In particular, if you are moving through a lens then things that are far away get blurry.
2) More to the point if there is something that causes supernova light to go funny on the way to the earth, that whatever causes the light to go funny will also affect anything beyond the supernova. Which will result in all sorts of lensing effects.
Well, we know that the speed of light doesn't change to a high degree of accuracy. This doesn't necessarily mean it can't, but it certainly doesn't (at least not by any significant amount).How do (1) and (2) prove that light can't change speed?
Because when you have a change in the speed of light it impacts everything we see whose light was en-route to us before the change in speed. So, if there were changes that started to be detectable at, say, 1 billion light years, they would be even more apparent at 2 billion light years, and so on. But the speed of light is highly uniform all the way out to the CMB.How do we know "anything beyond the supernova" is not affected?
Looks like a terrible fit. At z=1, the least-action predicted bightness is ~2/5 of a mag low, which is 1.4x too bright. If I remember right, the observed brightness deviation (cf a matter-dominated Universe) is only ~1.5x at z=1.