>> Why exactly is dark matter unintuitive to the layperson?
For me it's because the explanations don't actually make sense. The classic example to me is the galactic rotation "problem". It gets resolved by suggesting a spherical cloud of dark matter surrounding a galaxy. Great, but why would it affect the galaxy normally but take on such a distribution? The solution raises more questions than the problem. Not to mention it's a whole new kind of matter we can't detect. It's almost magical thinking.
> Great, but why would it affect the galaxy normally but take on such a distribution?
Electromagnetic interactions radiate off energy but not angular momentum, so a spinning sphere of gas will flatten over time. Dark matter doesn't interact electromagnetically and thus sheds energy much more slowly.
Until you have it properly explained it just looks like a kludge. It’s an obvious extrapolation once a number of fundamental concepts have been understood, but these are concepts you won’t be exposed to outside of a physics university education.
That’s all it is I think. Sabine (and probably others) have done a great job of explaining these concepts for the layman audience.
This article, and so many like it, don’t do that. So the physicist is left shaking their head, and the layman comes away still thinking “what a giant kludge that dark matter is”.
Intangible matter that can neither be seen nor interacted with outside of gravity is unintuitive. It can sound like "what if we're all just in a simulation, man?" but coming from the best science apparently has to offer.
That's exactly what neutrinos are in terms of human experience. Ridiculous amounts of neutrinos are flowing trough the whole planet and trough you like we are nothing.
Honestly "Dark matter is also believed to interact with ordinary matter in ways other than gravitational." is wishful thinking. Why? We have no a priori reason to believe that matter must have multimodal interactions, and there is potentially a real ontological crisis. If dark matter only interacts gravitationally - which even people who don't "believe in dm" must accept is a possibility, them dark matter is unfalsifiable, so we have to be ok with the possibility that there is something in the universe that exists but we cannot ever satisfactorily argue that it does. LCDM advocates know that they are on philosophically shakier ground if that's the case, but aren't brave enough to admit it because they are afraid it weakens their main cause by association (to be fair it does, we should probably be exploring other explanations first)
> We have no a priori reason to believe that matter must have multimodal interactions
No, but as a posteriori reasons go "everything else couples to the weak force" is a pretty good one.
> them dark matter is unfalsifiable
Only insofar as all the ontological content of a physical theory are unfalsifiable: you can always shift complexity around between state and dynamics if you're willing to pay the price in elegance. Consider Kaluza-Klein theory, for instance. In some sense this demonstrates that classical electromagnetism is unfalsifiable - but no one actually cares.
I guess I take issue with the vagueness of "intuitive" because that's kinda sorta "just feels"/bias/projection about the state of "lay person" thought. As I said, germ theory is "invisible stuff that interacts with your body" and an interventionist god is intangible entity that can control your fate... And I think a lot of people believe in those.
For me it's because the explanations don't actually make sense. The classic example to me is the galactic rotation "problem". It gets resolved by suggesting a spherical cloud of dark matter surrounding a galaxy. Great, but why would it affect the galaxy normally but take on such a distribution? The solution raises more questions than the problem. Not to mention it's a whole new kind of matter we can't detect. It's almost magical thinking.