Arp has found differential redshifts associated with over 260 galaxies, and has published a catalog of hundreds of discordant redshifts. But his work has been ignored. Getting rid of the opposition. According to evolutionary theory, the bluest stars are the youngest, and, therefore, the most distant stars should be the bluest. This totally defies the speed theory.
Photons slow down.
Only one stellar distance measurement is reliable. Keep in mind that only one method of ascertaining stellar distances is accurate. It is the parallax method, which can only be used on a few of the closest stars. Quasars are a great headache to evolutionists, for they clearly disprove the speed theory. And without the speed theory there can be no expanding universe.