Have you seen this? https://t.co/ZkfoNH3LMY— Ian Robinson (@IanRobinson) August 1, 2022
Topics in the video:
0:23 What is dark matter?
2:22 Evidence for dark matter
5:11 Evidence against dark matter
7:25 If not dark matter, then what?
9:43 Why we haven't made progress
At 9:32 in the video:
The difference is the behavior of these fields or particles. It's the behavior that changes from the scales of galaxies to clusters to filaments and to the early universe. So what we need is a kind of phase transition that explains why and under which circumstances the behavior of these additional fields, or particles, changes, so that we need two different sets of equations. And once you look at it this way, it's obvious why we have not made progress on the question of what dark matter is for such a long time.
There're just the wrong people working on it. It's not a problem you can solve with particle physics and general relativity. It's a problem for condensed matter physics. That's the physics of gases, fluids, and solids and so on.
So, the conclusion that I have arrived at is the distinction between dark matter and modified gravity is a false dichotomy. The answer isn't either – or, it's both. The question is just how to combine them.