[Zamicol]

It doesn't, and the problems have only become more problematic over time, but it's the least bad hypothesis that's broadly accepted. I suspect a generational succession is required for new paradigms to be contemplated.

There are many researchers proposing simpler, novel, and testable solutions that seem to go unnoticed. For example, I'm a fan of Alexandre Deur's work. He has some simple and elegant solutions that I've never seen discussed even though they appear "obvious". For example, from 21 years ago: https://arxiv.org/pdf/2004.05905

That paper is suggesting that one of the reasons why galaxies are spinning faster than some calculations expect is because they're failing to account for the gravitational lensing of gravity itself, which bends gravity down towards the disk.

[mr_mitm]

That paper focuses on rotation curves, like all DM skeptics. I can only assume because this problem is understandable with high school level math. But that's neither the only nor the best evidence for DM. If your new hypothesis doesn't even mention the CMB power spectrum, it's not really worth listening, sorry. And to be taken seriously, it has to explain at least most of the data. DM does that, everything else does not.

[magicalhippo]

I'm just a layman, but in this[1] paper from 2023 Deur and his collaborators took his model[2] and applied it to the Hubble Tension problem. This paper does mention fitting the CMB well (as I understand it), and the model having no Hubble Tension.

I know his work has been contentious in the past, and that his past work has used multiple models that are not entirely compatible for different problems, weakening his claims.

That said, at least from my armchair it seems like a worthwhile direction to pursue.

[1]: https://arxiv.org/abs/2301.10861

[2]: https://arxiv.org/abs/1709.02481

[naasking]

> If your new hypothesis doesn't even mention the CMB power spectrum

MOND successfully predicted the first peak of the power spectrum. I wonder why everyone focuses so much on LCDM predicting the second peak.

> DM does that, everything else does not.

Whenever someone says DM "does that", it's often after its initial prediction was falsified and the calculation was modified in some way to account for the new observations [1,2]. This has been going on for decades, so that's hardly a ringing endorsement.

I'm not surprised mind you, this is the hallmark of the confirmation bias that's been characteristic of LCDM for decades now.

[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

[2] Not that MOND is a suitable replacement because it too has its problems. My only point is that this tendency to sweep these inconveniences under the rug as if DM is a compelling and successful theory and saying "nothing else does the job" is disingenuous at best. What you should say is that "nothing does, period, not even our best DM theory", because that's the truth.

[sfifs]

The phrase "Dark Matter" literally means we don't know and therefore until something testable is postulated and tested (to be fair i believe some candidates have fallen by the wayside over the years as measurement has improved), it's principally equivalent to plugging in a giant X and giving it properties not unlike Fermi's famous elephant curve fitting comment.

[mr_mitm]

Just FYI I have a PhD in cosmology, so no need to explain to me what "Dark Matter" does or doesn't mean, but thanks anyway. It sounds like you saw that video by Angela Collier about how Dark Matter is a set of observations, and while I think it's a good video, it's a bit disingenuous to pretend that working scientists put theories of dark matter and theories of modified gravity in the same category. I know Collier literally says that MOND is a DM theory, but I respectfully disagree, as this does not reflect the reality of the language researchers use. Even if you didn't see that video, my point still stands.

Basically, our equation isn't working, and roughly speaking the equation has gravity on the left hand side and matter content on the right hand side. Matter tells spacetime how to curve and spacetime tells matter how to move, is the old motto. Because the equation isn't working, we have two options: modifying the left hand side or modifying the right hand side (or both). In my perception, researchers refer to the first option as theories of modified gravity, and the other option as theories of dark matter.

Putting both options into one category is over simplifying the situation and isn't helpful.

[andrewflnr]

She's done some interesting stuff, but I really hate that Collier video. It seems to have badly muddied the water.

[tekla]

Hey I'm sure a bunch of Youtube videos from Collier and Sabine makes you an expert in the field of physics because they make you feel smart.

[flqn]

"Just FYI I have a PhD in cosmology" is the credentials for the poster being an expert.

[teamonkey]

> I suspect a generational succession is required for new paradigms to be contemplated.

There are a constant stream of new paradigms contemplated (including this one!)

The problem is that they’re contemplated, tested and found wanting.

The notion of dark matter (and dark energy, which is a completely different animal) isn’t hanging around because of stubborn professors or a lack of imagination, it’s because nothing better has come along yet.

The good thing about this theory is that it seems easily testable. Maybe it’ll be different.

[mnky9800n]

Change happens in physics one funeral at a time.

[DrNosferatu]

Very true - but the CMB has outlived quite some funerals.