In the real world of laboratory physics, photons lose momentum as they pass through a dusty plasma. Chen even showed a correlation between the amount of current and charged particles present and the amount of redshift. In the real world of physics, photons interact with a "medium" and transfer energy to it.
Only in the realm of LCDM "magic" do forms of mass (dark matter) not interact with photons. That's one of the key ways they use to try to tap dance around the redshift processes in plasma that the mainstream forgot to include in their models. Because they don't allow for even a *tiny* bit of redshift to be related to momentum loss of the photon, they also need magical forms of energy which nobody can explain, as well as the ever magical, never demonstrated "space expansion" genie. All of that metaphysical nonsense is necessitated by their *outright need* to deny the role of inelastic scattering in space.
The only reason that any of those magical ad hoc gap fillers are necessary is because they can't admit to their very simple, and their very obvious mistake as it relates to scattering. Photons are scattered by mass, and lose momentum to mass. Any missing mass is likely to be ordinary mass, not 'invisible' mass. The reason they grossly underestimated the mass of galaxies in the Bullet cluster fiasco study is because their models were wrong, and they underestimated the amount of loss of light due to scattering in the first place!
Dark matter in particular has been the single most expensively 'tested' theory in the history of physics, and it's been a complete dud in the lab. No other hypothesis has enjoyed so much financial support, and delivered so little tangible evidence, or so few 'successful predictions' related to the outcome of various experiments.
Meanwhile no model other than the standard particle physics model has been as 'tested', nor has been so successful at making useful laboratory predictions as the standard particle physics model.
It's time for the mainstream to wake up and smell the coffee. They've simply been underestimating the amount of scattering going on in space, and it is all caused by ordinary 'missing mass' that's all baryonic in nature.
The moment they wake up from their illusion about a lack of inelastic scattering in a dusty plasma "space", their whole jig is up.
IMO it's quite revealing that the only published paper that ever ruled out any type of inelastic scattering (Compton scattering only) as the full cause of photon redshift was written and published by Fritz Zwicky while he was trying to 'sell' his own 'tired light' theory. No other type of scattering has even been "tested" in published papers.
If you read Zwicky's paper, his argument amounts to 'it can't be Compton scattering because distant galaxies would be "blurry" and they aren't blurry. If however you look at various galaxies, they do of course become "blurrier" with distance.
In order to continue to perpetuate the 'space expansion is the cause of photon redshift' dogma, they have to 'pretend' that "space" is "pristine" with respect to a complete lack of inelastic scattering potential. That's not even a logical premise when you look at Hubble images which show huge 'clouds' of various dust spread throughout the universe.
The mainstream is just emotionally attached to "being right' with respect to the cause of photon redshift, so they basically have to live in pure denial of the lab results which consistently show that photons transfer some of their momentum to the plasma medium.
The tap dancing I hear on that issue over at Reddit is also rather amusing. All 'pseudoskeptics' are reduced to citing themselves as the one and only "sole authority" on all tired light theories, and not one can raise a single objection to Zwicky's own 'tired light' model.
It's a lot like a Mexican tap dance around the physics of inelastic scattering in the "real" world lab experiments.
Yep, it's exotic matter turtles, all the way down.
Two more dark matter tricks, and no treats.