- #1
fbs7
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If I take a big, uniform blob of gas that is not spinning, and mark its limit as the limit of a system, then even if that big blob of gas coalesces to make a galaxy, it will not start spinning by itself: its own gravity is an internal force, and conservation of angular momentum says I need an external force to add angular momentum to the system.
As galaxies spin, either:
(a) my big blob of gas was already spinning before it started to become a galaxy, or
(b) there was some external torque applied to my system
So, what's the best explanation as to why galaxies spin?
As galaxies spin, either:
(a) my big blob of gas was already spinning before it started to become a galaxy, or
(b) there was some external torque applied to my system
So, what's the best explanation as to why galaxies spin?