Actually I might have done goofed with that one; now that I think of it, if you assume some jackoff amount of computing power then a human brain (assuming nothing uncomputable happens there, so sad Penrose noises) could be simulated from first principles for a limited amount of time, no actual proof of possible future outcomes needed. This still leaves the problem of how exactly do you get all the data for that (and I think any uncertainity would require an exponential increase in paths you have to simulate), especially without killing the human in question.