Huh.
I thought that there was a solid theoretical basis for the density wave hypothesis. But TFA implies that the main constraint was consistency with the Hubble tuning fork diagram.
That would be funny, because I've never really understood the density wave hypothesis.
The Hubble fork isn't "wrong". It's just a classification scheme. The fork has nothing to do with how spiral structures form or how long they last, it's just a way to quickly describe them.
Given that most cosmology relies on a huge percentage of dark matter, which cannot be detected, and a huge amount of dark energy, with enormous conflicting calculations, I think it's fair to say that astronomers are wrong about a lot of things.
the site is such a crap on mobile, low contrast letters, and that header that pops up and takes 30% of the screen every time you scroll up a pixel
I think that [1] is the paper that this is based on. I don't work on dynamics and I found it pretty readable. Most of what is in the article is in sections 3.2, section 4 (discussion) and section 5 (conclusions).
[1] https://arxiv.org/pdf/1904.11436.pdf