Okay I have some thoughts. I'm going to be taking a more computational approach.

So we have no free will. Everything we do is determined, i.e. given the current state of your brain, as well as extraordinary advanced technology, you can "calculate" what your next behavior will be. An issue arises: you are not a brain, but a brain in a body. We are not goop floating in a void, but a sensing and acting entity.

I'm not much of a Cognitive Psychology kind of guy, but one of the more interesting theories that has emerged in recent years is embodied cognition. This theory is a reaction against the traditional "brain in a jar" approach where cognition occurs only in the brain, and instead posits that cognition is a process of the brain and the body. The body's sensors structure incoming information before it sends it to the brain. This "re-structuring" of information is so complex that these sensors, as argued by proponents of embodied cognition, perform a computation on information before it reaches the brain.

Okay, so we can't just take our brain's state in order to calculate our next behavior, we need our body's state as well. We put that into our Human Predictor 9000.

But another problem arises: we are not just a brain in a body, but a brain in a body in an environment. That is to say, we are not just a body floating in space but are a body forever grounded in an environment. This environment acts on us in so many ways. We're talking background radiation, oxygen levels, amount of green things we can see in an immediate moment, how much stuff is touching our skin, voices and other sounds of events happening in our environment. We've established that our body is just as integral to cognition as our brain, but our body, like our brain, is exposed to all these happenings in our environment. You know what that means.

Time to simulate the universe.

Maybe it's a big step to go from our local environment to the entire universe, but if we don't then we will have to draw a line somewhere. Drawing a line, however, is going to create a computational model which, at some point, deviates from the modeled reality. At this point I'm reminded of the beginning of the Baudrillard book where a map that accurately depicts the territory would have to completely cover it. In this case we need to simulate an entire universe so as to understand our own. But don't we already have access to a simulation of our Universe? Isn't our own Universe the calculation of itself? Why bother creating a simulation? I suppose you could argue that a simulation would allow you to calculate the Universe at a rate faster than it actually proceeds, though I'll let other nerds think about that possibility.

If we take our Universe to be the calculation of itself, then we can extrapolate that to ourselves. What will I be doing in 60 seconds? We can calculate that, but it's going to take 60 seconds to run. If you want a better calculation than that then I'm afraid you're going to have to go and muck about in the nonsense world of thought and will.