Applying the 2nd law of thermodynamics to the whole universe is tricky, since if the whole universe would always increase entropy it would be like running down, and would imply some kind of begin and end state. That can't be the case. So in my point of view the total entropy of the whole universe is constant. Nevertheless for all finite subsystems, entropy most likely increases, but at the same time it decreases the entropy of the rest of the universe by the same amount. Yet, I have never heard of a physics law that states that. Interestingly, the idea emerged that gravity ain't a fundamental force but is a resulting entropic effect. It could explain why it never fits into the grand unification theory. In a small system a gas definately would tend to a higher entropy state, yet on very large scales the opposites occurs, since matter tends to cluster due to gravitational interaction like in large stellar gas clouds forming star systems, etc. If we were given photographs of such a system at different times, without knowing the scale and or the temporal order, what would we conclude? If the systems happened to be at a large scale system and we see the system becoming more clustered, we would know the order was forward in time, but is the scale was small we would have to conclude the order was backward in time. A theory that would have gravity emerge as a result of entropy also probably could get rid of "dark matter" and "dark energy", and that is one more puzzle solved. Could it be that the universe, which at scales we can observe is expanding and accelerating at still higher scales is at the same time contracting?