Is dark matter’s “nightmare scenario” true?

In physics, we have laws, rules, models, equations, theories, theorems, postulates, and maybe more. I can't think of one instance in which something has been "promoted" from one to the other after some data came in and couldn't even rank these in terms of certainty.

We still call it Newton's law even though we know it's wrong. We still call it Born rule even though it's one of the most tested things we have. We still call it the standard model even though it's the thing that works better than everything else. We call particular Lagrangians in Quantum Field Theory "theory" even though we know it's just a toy theory which doesn't describe reality. I mean, "toy theory" or "toy model" is a thing.

Physicists aren't nearly as nit-picky as internet commentators when it comes to this topic.

Probably because it's the only piece of evidence you can understand with just high school physics. Most laypeople have trouble understanding that the universe is not expanding from a single point, so how would they be able to understand what the cosmic background radiation is, much less why its angular power spectrum has peaks at particular positions?

It's a common pattern with crackpots as well, that they focus on "big" but easy to understand things like special relativity, which doesn't involve more math than you learn in high school. No crackpot ever revolutionizes condensed matter physics or statistical mechanics.

Although the bullet cluster should be a clear indicator as well, the rest of the evidence of DM appears much more subtle to a layperson.

Anyway, cosmology is a weird topic which not only HN reveals tons of arrogance over. Lots of misplaced skepticism. (Probably similar to the Covid topic.)

Dark matter is not a “recursive property of gravity” because it’s not consistent like that, as your own initial objection suggests.

The concept of a particle that only interacts via gravity is straightforward. Consider neutrinos, which only interact via gravity and the weak force. Trillions of them pass through your body every second. Take away the weak force interaction and add some mass, and you have a dark matter candidate particle.

> I fail to see how dark matter could ever be falsified.

You’d have to explain what should be done about that. It could nevertheless be a correct theory, and we might one day verify it more directly.

Naive falsificationism is an almost useless principle at the frontiers of modern physics. We’re long past the days when you could run some simple experiments and come up with a clear yea or nay. That’s living in the 19th century, basically - which admittedly, many people still seem to want to do.

You're absolutely right and this is the one thing about dark mayer that doesn't sound like "just keep sprinkling it on your problem till it works."

I don't know enough about the found examples of gravitational lensing to know whether all possible arrangements of black holes that could have the same effect, have been considered and found lacking. But I presume so.