There are some things that are inherently unknowable. One very important instance of this is the position of an electron. One can never know the exact position of an electron, only a probability that an electron exists in a certain area. Sure, if you knew everything about everything (and I mean EVERYTHING), then there is no reason you would not be able to plug numbers (a lot of them) into formulae (very complex formulae) to figure out future events. However, this would require knowing everything, which is quite a task to undertake. (Imagine trying to understand the simple task of enumerating every charge source in existence).