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Jan11-12, 09:30 AM
P: 15,202
Quote Quote by DaveC426913 View Post
A large volume of gas and dust will not have a net zero angular momentum. It would be fabulously unlikely that the momentum of each of uncountably large number of molecules would add up to zero.

So any cloud that is condensing will have some. By the time it's condensed a hundredfold, and the angular momentum is preserved, the proto-system will certainly have a net rotation, no external torque required.
Per the dominant hypothesis (the Solar Nebular Disk Model), it would be unlikely for the cloud to have a sizable angular momentum without some external torque. There's the angular momentum problem to consider. Our sun comprises over 99.8% of the total mass but less than 4% of the total angular momentum of the solar system. The nebular model solves this problem: Stars selectively attract those particles in the cloud that have very little angular momentum. In solving this problem, it introduces a new problem. Where does the angular momentum in the nebular cloud come from?