3 ms·
Rotation speed, rotation speed, rotation speed ... that's always been the poster child for dark matter. But do we truly understand how galactic rotation speeds
by PhantomGremlin 10y ago
Rotation speed, rotation speed, rotation speed ... that's always been the poster child for dark matter.
But do we truly understand how galactic rotation speeds should vary with distance? A typical galaxy has a hundred billion stars in it. Given such a complex system, can we truly simplify the expected rotation speed to something like "distance squared from the galactic center"?
The "three-body problem" is difficult enough, do we trust our approximations to properly model the "100,000,000,000 solar system problem"?
- EdHominem 10y agoThere's a difference between "complex" and "has no closed-form solution". It's actually a very simple calculation. But fwiw, a lot of thought and tests have gone into showing that gravity works the same way with feather and bowling balls. With big masses and many little ones. If you have a reason to think it doesn't, discuss it and propose tests...