I have been reading the archives of Physics Forums, some threads about the expansion of the universe and also the upcoming Heat Death that people keep talking about. However, there are a few things that keep bugging me: First of all, atoms have not so far shown any tendency not to cluster together, like they do today in galaxies and so forth, so why is there a reason to believe that all matter should be ripped apart? Increasing entropy, they tell me, but that brings me to another question which as that as to howt eh universe is considered a closed system or not. Because as far as I know, Boyle's law only applies to closed systems. I was reading something about this once, about how life came to be, because it shouldn't really have if there is a constant strife for increasing entropy, as cells and all kinds of living organisms are really a very orderly form of being. However, since the earth is not a closed system as such this was possible, and I gather this is because it is in space, and therefore the universe should not be striving towards entropy. But it is? What am I missing out on?