Hello! I was thinking the other day, of the earth's rotation around its axis. If one spins a boiled egg, it maintains spin longer than does an unboiled. Eventually both stops because of the friction against the floor, but not at the same time. The earth has different levels of viscosity and is exposed to alot of internal friction, just like the unboiled egg. Well the egg seems to violate the principle of conservation of angular momentum. So why don't the egg act like the earth? I looked into it and found out that the conservation of angular momentum only applies to angular momentum of what's referred to as an isolated system; this is what's said about an isolated system: "An isolated system implies a collection of matter which does not interact with the rest of the universe at all - and as far as we know there are really no such systems. There is no shield against gravity, and the electromagnetic force is infinite in range. But in order to focus on basic principles, it is useful to postulate such a system to clarify the nature of physical laws. In particular, the conservation laws can be presumed to be exact when referring to an isolated system" http://hyperphysics.phy-astr.gsu.edu/Hbase/conser.html#isosys After reading this my question changed to: What keeps the earth spinning? Seems like it depends on whether or not you attach the point of reference to the rotating metric, when doing calculations. If you attach the point of reference to the rotating metric, which we do(it's a flexible way to get rid of things like torque and coriolis force etc.) the friction becomes really nasty to deal with. I then came across an interesting solution to this. What it did was basically that it addressed the nature of torque and the Coriolis forces as dynamic properties of the spacetime metric and the stress-energy tensor, detaching the frame of reference from the rotating metric. Making the spacetime not only curve, but curl. Any thoughts or corrections to this idea? I found it quite interesting. I'm not sure I posted this in the right place, bare with a fragile newcomer in case i didn't.