Re: Dark matter believers
"The reason you need dark matter"
To be clear, there is no the reason you need dark matter. This is the big problem all the crackpots complaining about it miss - there are multiple different, entirely independent observations all saying that there is a lot more mass out there than we can see in stars and other baryonic matter. Galactic rotation curves was one of the first lines of evidence and remains one of the best known, but it's far from the only one. And since the different bits of evidence come from many different places at very different scales, no single issue like an argument over the distances to a couple of galaxies can ever be a reason to just throw the whole thing out. Whatever turns out to be the answer for this particular galaxy, it will have no bearing whatsoever on measurements of galactic cluster masses, measurements of the cosmic microwave background, direct observations of gravitational lensing, or a wide variety of other observations.
This is why dark matter remains the overwhelmingly favoured theory among the people who actually know what they're talking about. Plenty of alternative theories have been proposed, and some of them even do a decent job of explaining one specific set of observations (most are just mindless crackpottery and conspiracy theories that don't even manage that). But I'm not aware of a single one that manages to cover even just two separate lines of evidence.
So no, dark matter definitely can't be explained away that easily. Even if you come up with a brilliant explanation that fits galactic rotation curves perfectly, if it doesn't also explain galactic clusters, the CMB, the Lyman-alpha forest, the shape of the universe, the large scale structure of the universe, and a bunch of other stuff, you have done basically nothing in terms of explaining away dark matter.
Biting the hand that feeds IT
