>>11135999Nah, I think you're misunderstanding. The Liouville theorem is in classical mechanics not quantum. Search for it on Wikipedia and you'll see an animation of what I'm talking about.
Nobody does quantum mechanics in phase space (although you can make it work), because position and momentum are conjugate variables in the uncertainty relation. You can't have a well-defined point in phase space in quantum mechanics. In fact the uncertainty relation is the key to a better way to think about the degeneracy pressure. As you confine something to smaller and smaller volume you need to give it higher and higher momentum to do so. This is true for bosons too, since the energy of the lowest excited state should increase as the volume decreases, but it is even worse for fermions because they can't all sit in the lowest state.
