(For example, a spherical cosmic void surrounded by a spherical mass distribution cannot be affected by what the outside mass is doing. As stated by the second law of thermodynamics, the entropy of a given system only increases over time and only. Some regions will likely never collapse at all. Yes, entropy always increases in our universe. Some regions will certainly collapse (and bounce) before others do. A Big Crunch will be a messy affair, not even describable by the same Friedmann equations as the rest of cosmic evolution owing to the complete breakdown of homogeneity. And in fact that is consistent with other lines of evidence, like the increasing inhomogeneity of the universe over time. Rather, we should realize that because of the second law, a Big Crunch will look nothing like the Big Bang. It is highly questionable to suggest that a Big Crunch could reverse entropy. My suggestion is to go slow your first time around and take it all in.

The narrative in Entropy : Zero 2 consists of several deep layers. But if your theory is found to be against the second law of thermodynamics I can give you no hope there is nothing for it but to collapse in deepest humiliation. Step into some new boots (and a new body), and re-enter the Half-Life universe once more, as the pessimistic, wisecracking, door-kicking zealot known as Bad Cop. Indeed, the implication is that the universe must ultimately. If it is found to be contradicted by observation - well, these experimentalists do bungle things sometimes. Similarly, if the universe is an isolated system, then its entropy too must increase with time. If someone points out to you that your pet theory of the universe is in disagreement with Maxwell's equations - then so much the worse for Maxwell's equations. Entropy is a measure of energy dispersal, in units energy over temperature (joule per kelvin (J/K)). The law that entropy always increases holds, I think, the supreme position among the laws of Nature. The Universe has entropy, measurable in principle but not in practice.

Universe entropy