In 2384, Captain Brown of the U.S.S. DeLorean travels back to the early 21st century, a time before Nero appears in the past and alters the timeline. Up to this point, we have seen ships in the various series end up in the past, and return to their present, which occurs after Nero. Is there a subjective component to all this? Since Nero had not traveled to the past in their subjective future, his alterations haven't yet occured?
And what if the U.S.S. DeLorean travels back in time from the Prime universe in 2390, after Nero's trip. Would the DeLorean return to the future in the JJverse? And if he did, wouldn't it be Captain Brown's first duty to try and correct the alteration?
If they don't want ships jumping timelines, wouldn't Nero's trip end time travel in the prime novelverse?
Why would it? The Abrams timeline doesn't replace the Prime timeline or supersede it in some kind of hierarchy. It's just a forking of the road, one of millions of coexisting branching histories.
As a rule, if you alter nothing in your past, you return to the timeline branch you started from, regardless of how many independent branchings might have split off between your origin and destination dates. Presumably this is because you're quantum-correlated with that timeline and it's the natural one for you to return to -- or, as per the DS9
Millennium trilogy, because that's the timeline that your "Feynman curve" through spacetime is anchored to. However, if you take action that generates an altered timeline, then naturally you're going to be quantum-correlated with the events you participated in, so from that point on you'll be entangled with the altered timeline, and that's the one you'll find yourself in if you travel forward. It will look to you as if your actions have overwritten your home timeline with a "new" one, but in actuality they coexist side-by-side along with countless others. (Keep in mind that the 285,000 parallel timelines seen in TNG: "Parallels" were only the ones where an
Enterprise-D with a Worf aboard passed by that particular quantum fissure at that particular time. Which makes them a rather narrow subset of the total multiverse.)
So your path into the future is determined by which of those many branching timelines you have a direct correlation with, either because you came from it in the first place or because your actions created it. You won't veer off into a timeline created by a different set of time travelers at a point in history you didn't visit, because you have no correlation with that timeline.
In the universe that Voyager and Enterprise established, there is a time police that prevents any time travel incident, with ships that exist outside linear time and monitor any changes. That means Nero's actions would be prevented and the timeline would be restored. So in the prime universe, nothing ever happened.
No, because even time cops aren't omniscient. As far as anyone in any future extending forward from Primeverse 2387 is aware, Spock and Nero simply fell into a black hole and disappeared, the end. And even if scans of the red-matter black hole did provide enough data to show that they went back in time, that event did not endanger the existence of the Prime timeline, so there is no reason to undo it. It's a simple fact of life that parallel timelines exist by the gazillions. Temporal agents simply don't have the time -- no pun intended -- or the resources to undo the creation of any of the innumerable parallel timelines that coexist harmlessly with their own. Their efforts would be concentrated on undoing alterations that jeopardized their own existence.
