This isn't space/time, but it is existence I suppose - I used to think that everything we do was on a fixed track, a form of predestination in which we were always going to make the same choices at any given point. I have since further refined that idea to come as a result of brain chemistry - that it is impossible for us to "will" ourselves to do anything that we weren't already going to do, because all our actions are based on an unpredictable concoction of electrical impulses and hormones pumping through our system. So we can't know ahead of time what we're going to do at any given point, because it depends on those signals and impulses and chemicals, and consciousness is only an awareness of the result, not a motivator of action.

This also a way of saying I don't believe in a mind/body duality, that your brain and your mind are one, so what seems like an instruction your mind is giving to your brain is just one impulse from one part of the brain to another. This is also why I don't think you could be a disembodied brain in a jar, because all of the inputs you're receiving are from chemical reactions in your body, and if you didn't have a body, you would have to be receiving those inputs some other way, and that's just some other sort of "body" (i.e. what's the difference between a sack of carbon and a computer if they're sending the same chemical signals?).