Study: Dark matter does not exist and the universe is 27B years old

Another analogy: we find a person, shot, in his home. There's a bullet inside the body, calibre and rifling marks point to a particular type of firearm, powder burn marks indicate a point-blank shot, all the CSI stuff. But the murder weapon is nowhere to be found. Do we assume that the weapon – and the perp – does indeed exist, or should we "tweak the model" to include a way for bullets to spontaneously materialize out of thin air and kill people?

> Chalk it up to ignorance, if you'd like, but I still feel like asking "are you sure you can't fix the model instead of plugging it with some unobservable feature?"

I don't understand how people think there's a distinction between "introducing a particle" and "fixing the model". Doing the former is doing the latter! Anyway, yes I do chalk it up to ignorance, because that's still a strawman, assuming some kind of a Scientific Orthodoxy that has decided that Dark Matter It Is, Claiming Otherwise Is Heresy.

It's tiring to repeat this in every thread about DM, but – everybody and their dog has been testing the dark matter hypothesis for several decades now, obviously, because finding definitive evidence against it could be worth a Nobel, and so would figuring out a way to detect dark matter particles in laboratorio. And thus far they've found zero contradictory evidence, but instead in several other subdisciplines of astronomy, observations have been made that just happen to fit exactly the same sort of dark matter model that was originally only devised to explain the galactic rotation curves, without any fiddling. All the new evidence has simply tightened some parameters of the model that used to be less well known.

Meanwhile, no competing hypothesis has been able to explain all the different observations that the the single unified dark matter model does explain. Different non-dark-matter models may be finetuned to explain some pieces of evidence, but that makes them unable to match other evidence.

Nobody is claiming that there couldn't be a nice elegant dark-matter-less model that explains everything neatly. Most astrophycisists and cosmologists would be elated if one were found, and people do keep on looking. But as long as no such thing exists, we must assume that something that walks like a duck and quacks like a duck is, indeed, a duck.