My understanding of physics is this:
Continue on with this thought.Who or what predetermined the future.
Newtonian physics gives us a model of a clockwork universe where everything is predetermined. If only we knew the current state of the universe in sufficient detail we could predict the future with complete certainty.
Only trouble is, it doesn't work like that.
Quantum mechanics is something I'm presently trying to get my head round (more the philosophical implications than the detail - I'll leave that to the physicists). Particularly the idea of decoherence interests me. In simple terms, this is when a particle stops acting like a wave and starts acting like a particle. It's triggered by interaction with other particles (ie. measurement or detection). A wave spreads out in all directions, is in many places at once. A particle has a particular location. The wave aspect (which is very real, in the sense that it has interference patterns for example) describes the probability of the particle being at any given place, and decoherence is when the particle "chooses" to be in one place based on that probability wave. That's a gross oversimplification but I think it's a pretty good model for a non-physicist to work with. The point I'm getting at is that it seems to be a really random event. The probability is predictable, the actual outcome is not. This sort of non-deterministic behaviour is what Einstein was railing against when he said "God does not play dice".
I personally find a lack of determinism troubling. A random event leaves more to be explained in some sense - what decides that the random outcome will be this and not that? Some people might be happy to give God the job, but this is no explanation in my opinion. The most elegant model, in my mind, is one in which all possible outcomes occur in an equally real sense. We cannot experience all these realities interactively (ie. one reality cannot be aware of another). Effectively we have infinitely many parallel universes branching into infinitely many more at every instant of time. Looking at one branch it seems that the course that branch took was random, but in fact all available courses were taken. On some level that may be mind-boggling, but it's also very simple.
The implications are interesting, for example time travel paradoxes are no longer paradoxes, since they invariably assume one course of events. Every possible course our lives could take is taken, by ourselves, in a very real sense. Any bad decision you ever made, which could have been done better, was done better, by you. Not in this branch of reality but another equally real one. It's reassuring to think that. But this does not give us Free Will, since your actions remain predetermined. But what is also predetermined is that you will live out every possible course of action you could do. Who needs Free Will when you can have every possible future, and not be stuck with just choosing one. Now that's having your cake and eating it (and not having it, and having it but not eating it).
Enough. Time for someone else's thoughts.