I've constantly heard professors answer questions about entropy with a statement about how even if the entropy of a system is decreasing the entropy of the universe is increasing. How can we discuss the entropy of the universe if information can't be communicated between all points in space at the same time? Or rather, how does relativity mix with entropy, if at all? edit: I just realized that this might have more to do with relativity than with thermodynamics. Moderators feel free to move this post.