[jtmckinley]

I think what VAX wrote echoes what I wrote and is what I was alluding to, at least regarding conservation of angular momentum, though I didn't mention that explicitly. Essentially, I think, feel free to correct me if you think I'm wrong, is that any system of particles has a fundamental angular momentum due to the fact that they're all moving relative to each other, unless they are all heading toward a fixed point of course. Consequently, conservation of angular momentum inevitably results in spinning objects formed from a cloud of individual particles due to the non-uniformity of motion of the particles in the cloud. The point is that if you add gravity into that system, the particles attract one another, and there is an angular momentum of that system that is conserved when they coalesce. Therefore, if angular momentum is conserved (which it is, as far as I know, at least in the case of dust particles and other macroscopic entities) , it is inevitable that condensed clouds of gas or dust will exhibit rotation. VAX rightly points out that the idea of curved space isn't necessary to explain this behaviour, Newtonian mechanics will suffice. I only mentioned curved space because that was easy to make the "marble" model with.