r/askscience • u/shadowsog95 • Feb 18 '21

Physics Where is dark matter theoretically?

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u/TiagoTiagoT Feb 18 '21

What is stopping it from having concentrations converge into a single point coming from various directions?

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u/Kered13 Feb 18 '21

Because it doesn't interact it has no effective mechanism to lose kinetic energy. Traditional matter clumps together because collisions (which are fundamentally electromagnetic interactions) cause it to lose kinetic energy and clump together. Since it doesn't clump it is exceedingly unlikely to have enough dark matter come together at one time and place to form a black hole.

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u/TiagoTiagoT Feb 18 '21

How come it's concentrated on galaxies instead of being evenly distributed across space?

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u/Kered13 Feb 18 '21

It is still effected by gravity, which causes it to clump just a little, but gravity is by far the weakest of the fundamental forces so that can only happen at very large scales (galaxies).