I’ve thought about this too, if dark matter is affected by gravity but not other forces, wouldn’t that mean if we were able to drill to the center of any substantial gravity well (say the moon rather than the earth), would we be able to detect a big clump of dark matter? Does that mean there’s a bunch of dark matter at the center of all the stars?
If we assume dark matter is a particle that only reacts via gravity, well, I'm not so sure you will.
The question here is how your particle that only reacts via gravity loses energy. First it will have whatever momentum it has from the galaxy relative to the speed of our solar system and planet. Then as it falls into our gravity well it picks up even more speed. When it reaches the center of our planet it's hauling ass with no brakes so no reason to stop, so it goes screeching out the other side. Even if you somehow had a dark matter particle at 0 relative motion to your gravity well before it fell in, how long is it going to take to bleed off its gravitational energy?
I find the description of dark matter confusing. I hear statements like "dark matter has negligible interaction with ordinary matter". So, how do scientists know that dark matter exists?
"The answer is that our galaxies spin too fast for the visible matter alone to hold them together. Dark matter, which makes up 27% of the universe, provides the additional gravitational force needed. In contrast, visible matter only makes up 5%."
However, I'm left wondering whether dark matter does or doesn't interact significantly with visible matter.
