This question already has an answer here:
I am nothing but a curious layman so don't go too technical on me.
First of all, I am well aware that a lot of people consider the question of determinism vs indeterminism to be unsolved and others claim it is solved. That is not what this post is about, so let's not digress into heated debates over the validity of the interpretation I am asking about here.
Now if something like the copenhagen interpretation or grw is true then there is inherent randomness in nature. Before measurement, there is no truth about what outcome will be. There is no mechanism deciding that the infamous Cat will die or survive. There is no fact until measurement is made. I.E. the future is 100% open.
But how can that be reconciled with the view we get from special relativity? That there is no difference between past-present-future? If I have understood the consequence of relativity correctly, that means that the "now" we experience is basically just a slice within a huge block of time. So the past is as real as now and the future too. And if that is the case then the future has to be fixed, otherwise what sense would it make to say that it already exists?