I struggle with the idea that 85% of matter is just missing. This just rings alarm bells for my mind. Danger danger bullshit alert. I am sure there are good thought our reasons, but not being in the field makes me wonder about it all.

On a side note, I saw today that there are giant magnetic fields connecting galaxies. WTF?

This helped a little:

https://astrobites.org/2020/08/...

So is this mass missing from formation or mass missing to even hold the galaxies together?

The missing mass is hiding in npm modules

The matter we see can’t explain the things we see, like gravitational lensing happening between two galaxies instead of around each one, or why the matter in galaxies orbits at a consistent rate, instead of being much faster towards the core and slower at the edges.

The simplest answer that describes all of the observations is a form of matter that only interacts through gravity, and that makes up 85% of everything. … which tells you that the other theories are totally cray.

Source: I get bored and watch science videos a lot.

It isn't "missing". We just can't see it yet. But we can't see a lot of things. The first exoplanet has been confirmed to exist in 1992...

But yeah, that is a pretty stupid name for "stuff that should be somewhere but hasn't been seen yet".

We just need to find a measurable physical "thing" that can both interact with whatever it is and another known measurable physical thing.

I really hope that there is an entire standard model for dark matter. Like, not just the “dark matter particle” but an entire class of them that interact and do things. And, I hope that these interact with matter in some way besides just gravity.

@Root If you look at the comments of the link I provided you will see there was a scientist that wrote some papers that eliminated the need for dark matter. The gist of it is that there is gravitational interaction that was not accounted for in the first place. When taken into account it reduced the required matter.

So dark matter is not "missing", it is matter that does not interact electromagnetically, meaning it does not emit light and therefore cannot be seen on a telescope. We know it is there because we observe the way galaxies spin, and the motion does not make sense based on the amount of matter we see. So what we are looking for is electrically neutral matter, which hopefully interacts through the weak interaction.

This could be neutrinos, for example, though the known kinds of neutrinos are not enough to explain the massive amount of dark matter we expect. If it is not neutrinos it could be black holes (they do not emit light, unless you want to go down the rabbit hole of Hawking radiation), and could explain it. If it is neither of those, it could be a new kind of particle, dubbed as Weakly Interactint Massive Particles (WIMPs). We don't know what hypothesis is correct, which is why research is being done in all directions.

@ess3sq PS. this is not chatgpt, it is my personal knowledge and an likely incomplete picture

I don't think it exists, at all. I think it's far more likely that our current gravitational theories are simply hugely inaccurate at huge scales, and we haven't stumbled across the right theory to explain it yet.

Problem is that dark matter is so well accepted that any physicist working on an alternate gravitational theory is treated like a pseudo scientific loony, so there's very little incentive for brilliant minds to think outside the box.