2 ms·
>Dark matter is assumed to exist from the excessively quick rotation of stars around the cores of galaxies. That's what initiated Zwicky's notion in the '30s.
by stan_rogers 7y ago
>Dark matter is assumed to exist from the excessively quick rotation of stars around the cores of galaxies.
That's what initiated Zwicky's notion in the '30s. It is far from being the only, or even the main, evidence for dark matter (which can be read as "mass effects we can detect not associated with matter we can currently detect").
- ncmncm 7y agoMore accurately: motion dynamics not compatible with both General Relativity and the mass we can see and reasonably infer. There is of course a stupendously huge amount of mostly invisible "interstellar medium", and even more "intergalactic medium", mostly ions of loose atoms and small molecules, and we use estimates of how much of that there must be. If its motion has anything to do with plasma fluid dynamics, all bets are off, because those equations are what mathematicians call intractable, and physicists would call career-limiting. They will happily declare 3x more unknowable Dark Matter than normal stuff before allowing plasma dynamics to have any effect on anything. Can hardly blame them.