I agree that QM explains the start of the universe, and the first fluctuations that eventually evolved into galaxies. But the actual evolution of galaxies is explained much more clearly by GR. QM does not have a good grasp on gravity, which is the major force accounting for the formation of galaxies. One of the goals of theorists who are working on the Grand Unification Theories (GUTs) is to combine all 4 fundamental forces into a coherent whole.
As I said, both QM and GR are powerful theories that taken together explain almost everything in the universe. However they do not play well together at intermediate, and very small, sizes. So there does need to be a better theory that will provide the same results as QM in areas dominated by particle interactions and the same results as GR in areas dominated by gravity. Right now trying to scale QM up to galaxy sized interactions is not possible, and scaling GR down to atomic sized interactions is also not possible. Heck I don't think it is feasible to scale QM up to baseball sized objects.
Bill Gill
