In the 2009 Star Trek movie, why was the new timeline considered acceptable?
In episodes of TOS and the movies, the crew would always go to great lengths not to alter the timeline and to restore any changed timeline to the original.
In the movie Spock seems to have no issue with the altered timeline and simply shows interest in the differences. Is that out of character? Why did he not do everything in his power to undo the damage done by Nero?
There were a number of different issues at play here. Let's get the two out-of-universe answers out of the way so we can see the real reasons in the universe.
Out of Universe:
In Universe (Looking at all the factors):
In other Trek situations, the timeline change had an immediacy to it. Either the characters in the story made the change (usually accidentally), or they were there when the change was made.
Also, in other situations, those taking on the responsibility to reset the timeline had more to gain than lose by resetting it. They would lose their lives, memories, and everything in their lives if the timeline were not reset.
Other than Spock, everyone involved had more to gain than lose by not resetting it. They would lose their lives, memories, and everything in their lives if the timeline were reset. (The mirror image of the reason above.)
The event that changed it (Nero destroying the Kelvin) was 20 years before anyone knew they were in an alternate timeline. This wasn't a case where anyone from the original timeline could change it back because they're at the point (in time and space) where the change happened.
The "incursion" was from someone else, in the future, not something done by anyone who has learned about the issue and could do anything (other than Spock).
Since the timeline had been altered, the only way to fix it would be to stop Nero. That can't be done by going to the future, since the changes in the timeline would not produce the same Nero that came back in time.
Not being able to stop Nero in the future would mean stopping him in the past, but even though the Narada was only a mining ship, it was so large and its weapons were so advanced, it would have taken many starships to stop it, which would have resulted in many more casualties than just the Kelvin being destroyed. The timeline would have been even more changed than it already is.
In other words, all those (other than Spock) who know about the incursion and change have every reason to want to keep the changes in place. Beyond that, even if they wanted to change it, Nero's future would no longer exist, so they'd have to stop him in the past, and they don't have the armament to do that without even worse losses than they've already suffered, which would mean more damage to the timeline.
As to why the Time Cops (Captain Braxton and the USS Relativity as seen in Voyager) didn't show up, that's anyone's call, but it might also have something to do with changes that happened during the Temporal Cold War that was covered in Enterprise. (Maybe everyone got lucky and Nero's incursion and creation of a new timeline resulted in no more Starfleet Time Cops!)
If anyone had a problem with the new timeline going the way it did, it was Spock. Nero destroyed his home planet. The simple answer is that there was nothing he could do. He and Nero were cast into the past by a force (black hole) over which they had no control and from which they could not return. Nero returned well before Spock (20 year, is it?), and so the damage was done well before he could intervene. Spock did all he could, and to worry about what was out of his control would be illogical.
And he did insist that Kirk find a way to become Captain of the Enterprise, keeping the timeline as in-tact as he could in that respect.
A point not considered by the submitter: In TOS etc, it is always persons from the original timeline who are making the supreme effort to restore their own timeline. In the reboot film, nearly all of the people who are even aware that there has been a change to the timeline are from the revised timeline. They naturally consider it their own timeline - why would they ever want to change it to someone else's, or even think it needed to be changed?
There wasn't a lot Spock could do about it. The timeline was changed as soon as the USS Kelvin was destroyed. The only way to fix it would be to go back in time and prevent the Narada from traveling back in time. And if Spock could do that he could've more easily prevented the destruction of Romulus.
It is also unknown whether the Temporal Prime Directive requires that Starfleet personnel fix changes to the timeline or simply do everything to preserve it. I think it is unlikely given the Federation's policies of non-interference.
Time travel and consistency are like oil and water: you can try to mix them all the way you want but at the end, they always end up separating themselves. This is true for science-fiction as well as for real physics and you can't do nothing with that. If you think that you had achieved a consistent view of time travel in a science-fiction serie, then it's because you have made a serious error somewhere but you haven't noticed it yet.
For example, if we talk about the millions of Vulcains killed by Nero, we are in an alternate timelime; therefore, these people are not the original Vulcains but copies who have been made in the alternate timelime in order to be killed but the originals remain there; untouched and unaware of anything particular.
It's like to want to kill you but instead of killing you, I make a copy of yourself - in a way totally unknown to you - and I kill this copy. You, in the meantime, you remain 100% unaware and unaffected of absolutely nothing. I could do this 1000s of times, you would remain exactly the same, both physically and mentally. The real clown here would be me, losing my time and my energy with copies of yourself that even you remain totally unaware of.
Furthermore, if travelling in the past create a new timelime, travelling into the future create a new one, too. Therefore, once you start time travelling, you cannot no longer coming back to your starting point, travelling instead to a new timeline everytime that you try; each of these timelines filled up with copies of all the people existing in the previous timeline. Who would care about the destiny of anyone in any of these timeline in this situation?
If time travel can really exist then destiny doesn't exist anymore.
Few issues... Spock and Nero were apparently thrown not just backwards in time, but also to an alternate reality. The timeline changed the moment Nero emerged from the black hole and destroyed the Kelvin.
The only conceivable way I see of 'fixing' that problem would be to prevent both Nero and Spock being thrown into the past by the black hole. Otherwise, if say Spock decided to slingshot his way into the future, he would simply emerge 129 years in the future of that ALTERED reality.
The events already took a radical turn before Spock emerged, but they also take place within an alternate universe. That's the only explanation why we saw no interference for why we never saw 29th or 31st century from intervening in this.
Besides, if anything, Starfleet of that reality would have access to a wealth of information to improve their chances and avoid some problems. This of course depends on how much future Spock shared with Starfleet of the past... but they would already have taken measures to maybe put into practice various things by having sensor scans of the Narada, etc.
I would imagine that in the most things, the technical and scientific prowess of both prime and nu Trek timelines remains the same for their respective times (23rd century - technology is basically the same)... it's just that the prime one didn't have the benefit of advanced SFX to showcase those advancements properly... and additionally, SF of NuTrek took different course of action after the Narada incident. Future Spock would simply try to steer certain things into a direction which would resemble his reality... but events would still diverge in many respects what with Vulcan's destruction.
So, I don't think there's any particular issue with Nu timeline existing because it doesn't have an inherent impact on the prime timeline. It could simply be taking place in an alternate universe of the 23rd century which was altered (and down the line, the temporal committee of that universe might not need to change anything as it was a predestination paradox that was meant to happen anyway).
As far as I can gather, Spock would struggle to make his case to the federation council- He would have to convince them that he is from a future that is better than the one they have been experiencing for the last 20 years- otherwise he'd be on his own- and he couldn't do much to alter the timeline- he's no Jim Kirk!!! My chief concern is where this leaves TNG and such- I'm guessing that THIS Jim Kirk won't follow the same stories as Shatner's. So will the events of "The Naked Time" happen, and does that mean that Riker and Picard would have no reference during "The Naked Now"?
