The question you are asking isn't a valid question, because it's based on the faulty assertion that "...everything in the universe degrades or rusts or tends towards decreasing complexity". That's just not true. And given you think it's true, the belief that you don't know something basic isn't an assumption.
There isn't a way to answer questions based on faulty assumptions, like "Why did you murder JFK?" People have actually been quite kind in giving you "sort of" answers such as "It came from the energy that the Sun pumps into the system."
I'll also point out that when people make the faulty assertion that everything tends toward decreasing complexity, they usually try to follow up with some intelligent design argument. You haven't done that in this post, but that is probably why you're getting answers that are a bit guarded or combative, because people are prepared for you to take this discussion to a truly ignorant place.