Re:Dark Matter Doesn't Exist
by naasking on Thursday August 11, 2022 @08:58AM
(#32424943)
If DM has to have a very specific initial distribution to reproduce what we see, for example, that too is a constraint but it's also fine-tuning. Another theory that is free of such parameters should be preferred. Some types of constraints really should decrease a theory's plausibility.
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MOND needs some pretty crazy arguing to explain decoupling of gravity from baryonic matter distributions. And it also needs a varying length scale parameter to account for different galaxy types. Particle DM can explain all of these things at the same time without re-tuning the model every time.
> MOND needs some pretty crazy arguing to explain decoupling of gravity from baryonic matter distributions. And it also needs a varying length scale parameter to account for different galaxy types.
You mean the theory that has received 2-3 orders of magnitude less attention than DM has some conceptual holes to patch up? Colour me shocked. The fact that DM still fails despite all of that investment should worry you more.
> Particle DM can explain all of these things at the same time without re-tuning the model every time.
DM has already been tweaked and fine-tuned to patch up its own endless list of holes, many of which were recently reviewed by McGaugh [1]. Many more remain despite that, like the dynamical friction discussed in this article.
Here's an explanation why McGaugh's work is highly dubious: https://www.preposterousuniverse.com/blog/2011/02/26/dark-ma... It also talks about the general problems with alternatives to particle DM.
Sean's breakdown is ironic, because every point he makes against MOND also applies to DM theories, particularly given new evidence. I have no problem acknowledging that MOND is inadequate given the data, but apparently it's difficult for DM supporters to similarly acknowledge that DM has been refuted. The core argument for DM rests on a theory (GR) that we already know must be incorrect due to its singularities.
Finally, I'll just note that literally nothing in Sean's post suggests McGaugh's work is "dubious" in the least, so I have no idea where you got that notion.