In some sense, time simply exists. There is no universal past to which one can travel. In fact, relativity has no implications regarding determinism vs. uncertainty. In this theory there is no universal present, and the entire past and futue of the universe are regarded as existing as an indivisible whole. Any conflict is, in fact, illusory.
Determinism concernes the question of whether every event is completely determined by a prior cause.
It says nothing about whether the event is there. After all, the future will be what it will be regardless of whether it is determined by prior events or not. The four-dimensional perspective of relativity simply forbids us to slice up spacetime, in any absolute way, into universal instants of time. The notion of two events in different places being 'simultaneous' is relative to one's state of motion. They may be judged to occur at te same moment by on observer, but one moment after the other by another observer.