Sorry to disappoint you Lack, but just because we can't accurately describe the physical universe doesn't mean that there's free will. It just means we can't calculate it exactly.
But don't worry, I think there's plenty of empirical evidence for free will, every time a person thinks about what to do next, for example.
Even a game like chess, where you're actively trying to predict what your enemy will do and move your pieces accordingly BEFORE he gets around to do it, which sounds like predestination par excellence, is a demonstration of free will, I've played dozens of game that started with the same moves, and they all developed differently.