Roger Penrose's Andromeda paradox offers some insight into the issue:
|[P]eople pass each other on the street [on Earth]; and according to one of the two people, an Andromedean space fleet has already set off on its journey, while to the other, the decision as to whether or not the journey will actually take place has not yet been made. How can there still be some uncertainty as to the outcome of that decision? If to either person the decision has already been made, then surely there cannot be any uncertainty. The launching of the space fleet is an inevitability. In fact neither of the people can yet know of the launching of the space fleet. They can know only later, when telescopic observations from earth reveal that the fleet is indeed on its way. Then they can hark back to that chance encounter, and come to the conclusion that at that time, according to one of them, the decision lay in the uncertain future, while to the other, it lay in the certain past. Was there then any uncertainty about that future? Or was the future of both people already ‘fixed’?|
Coupled with the fact that the mathematics of relativity does not single out any events over any others, it would seem to suggest the locus of all events that make up our history, or that of an object, is extend through spacetime as a world line. This would mean that, at every moment in time, it can be said that the Universe comprises all events along an objects world line. That is, past events persist in the structure of the Universe, while future events are "already there".
Wouldn't such a picture of the Universe have implications for Bell tests? Essentially, in a Block Universe there can only ever be one outcome in a Bell test because the outcome event (the exposure event of a Stern Gerlach plate) is on the world line of the SG plate, which extends through spacetime.