undefined | Better HN

0 pointsnaasking3y ago0 comments

> However, while I'm only a cosmologist and not a particle physicist, I find the implied assertion by proponents of MoND, that the existence of non-interacting particles is impossible, questionable.

I think this is a strawman. MOND proponents don't discount that some observations are better suited to a particle, they just assert that the particle dark matter sledgehammer is vastly overused, and that modified gravity has been unusually successful in cases where it had no right to be if gravity acts as it does under GR.

For instance, this review [1] of the astrophysical evidence by a MOND proponent makes a good case for MOND + sterile neutrinos. This review also covers numerous falsifications of DM, so if you're correct that DM can be falsified, why did these falsifications fail to convince the majority?

[1] From Galactic Bars to the Hubble Tension: Weighing Up the Astrophysical Evidence for Milgromian Gravity, https://www.mdpi.com/2073-8994/14/7/1331/htm

0 comments

2 comments · 1 top-level

sigmoid103y ago· 1 in thread

>why did these falsifications fail to convince the majority?

Because they are cherry picked. In the big picture, for every area where particle DM struggles, you will find a dozen datapoints where MOND struggles. Physicists are also wary of approaches like MOND+particle DM, because it just introduces more parameters which you can arbitrarily tune to explain data. It feels like every week someone comes with a new model that fits certain edge cases better, but doesn't actually tell us anything new or could act as a reasonable guide for future work. You can imagine it like fitting a polynomial of degree N to N data points. Yes it will fit perfectly, but that doesn't mean it's a good model. This is just sophisticated curve fitting to generate papers and not good science.

naaskingOP3y ago

> Because they are cherry picked.

Sure, as are the objections to MOND.

> Physicists are also wary of approaches like MOND+particle DM, because it just introduces more [...] You can imagine it like fitting a polynomial of degree N to N data points. Yes it will fit perfectly, but that doesn't mean it's a good model. This is just sophisticated curve fitting to generate papers and not good science.

That's exactly what's happening with cold dark matter models. I agree the state of things is unsatisfactory for either theory, we need bolder ideas. Superfluid dark matter was promising but doesn't currently match some observations. We need more of that.

j / k navigate · click thread line to collapse