#428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens

4595.164 - 4616.177 Sean Carroll

And there is a phenomenological fact about galaxies that in the interior of galaxies, you don't need dark matter. That's not so surprising because the density of stars and gas is very high there and the dark matter is just subdominant. But there's generally a radius inside of which you don't need dark matter to fit the data, outside of which you do need dark matter to fit the data.