Cosmology Has Some Big Problems

They have. Considerable effort has been expended trying to detect changes in various constants related to light, including speed but also some other things. It is expected that if constants were changing, spectra would change as well. So far as I know, all those results have been negative, but it's not for lack of trying. Similar arguments can be deployed for the nuclear forces as well w.r.t. spectrum, rates of fusion, various things you'd be able to observe in certain types of supernovae, etc.

One of the things I don't like about this genre of articles is that it's typically quite mistaken, if not outright disingenuous, about the current state of cosmology. From what I could see, the idea that cosmologists are all stodgy old fogies brought up in a paradigm of the Big Bang and who won't entertain any other thoughts is diametrically opposed to the truth. To my eyes, the field is a bubbling cauldron of various exotic ideas and attempts to resolve all these issues. There's no lack of theories in cosmology and attempts to resolve these issues, including many quite radical ones (the holographic principle, changing constants over time, heck even "Dark Energy" is quite radical in many ways even if it is also the accepted theory at the moment).

What we lack are theories that explain all the observations. Dark matter is favored not because it's the only idea that anyone has come up with, but because it's still the one that best fits the facts. (As PBS Space Time pointed out last week, ironically, the galaxies recently discovered to not contain dark matter are themselves quite strong evidence dark matter must exist: https://www.youtube.com/watch?v=5t0jaE--l0Y , because almost all other theories to explain galactic rotations are based on characteristics that can not vary by galaxy like matter distributions can. "MOND", for instance, is not "MOND, except in these two galaxies".)

If you can solve all these problems, as near as I can tell, you'll be celebrated, not shut down by the old fogerati. But be prepared for your theory to need to cover a lot of existing observations; we're centuries past "Well, what if gravity just worked differently?" or "What if the constants aren't constant?" You're going to need a great deal more detail than that.

> Big bang was only the accepted paradigm from the 60s (post CMB observations). We have had DE since Einstein in 1917 and DM since Zwicky in the 30s.

Admittedly the DE from Einstein is for very different reasons than the DE today, but we again had the big bang and no DE from the 60s until the 90s (observations from https://en.wikipedia.org/wiki/Supernova_Cosmology_Project) so they don't go hand in hand.

> I have no idea what that means. They literally observe the sky...

They mean you can’t look into the telescope and see the object, eg like going into my backyard and observing Mars or Venus, that you need to do elaborate post processing to resolve the target object from other collected signals and shift it into a visible form.

This is contrasted with early astronomy, where you could literally just look at objects.

I don’t know that this is a deeply significant point, but it’s at least understandable: if it’s not something you can look at, then you might be assuming your theory to interpret the evidence which supports your theory — that you’ve just begged the question.

I think the comment speaks to the breakdown in science education, but it’s a valid observation about failures in complex human endeavors.