Time Travel in the Abramsverse
"Whatever our lives might have been if the time continuum was disrupted, our destinies have changed." (Spock, "Star Trek (2009)")
Star Trek (2009)
In the year 2387, Ambassador Spock is on a lone mission to eliminate a supernova that is a threat to the whole galaxy. His plan is to create a black hole with the help of "Red Matter". Spock, however, comes too late, and the planet Romulus is destroyed. Nero, the commander of the Romulan mining ship Narada, blames Spock for the loss of his homeworld and seeks revenge. But both the Narada and, a bit later, Spock's ship are pulled into the forming singularity. The Narada arrives in the year 2233, attacking the USS Kelvin and killing George Kirk, James T. Kirk's father. This event sets off a new timeline, as evidenced by the different personal histories of the so far familiar characters, most clearly Jim Kirk. Spock arrives in the past 25 years later. He is captured by Nero, who is still in the 23rd century, and has to witness the destruction of his home planet Vulcan. This new timeline persists at the end of the movie and is not retroactively corrected in any fashion.
The basic plot of this movie boils down to the classic past incursion: Someone travels back in time, and intentionally or unwittingly alters the course of history. However, the time travel incident in "Star Trek (2009)" or rather its consequences are unlike any other ones that have been shown in Star Trek so far. The first difference is that none of the time travelers returns to the future, neither Nero who dies together with his crew nor Ambassador Spock who chooses to stay in the 23rd century as a moral support for the surviving Vulcans. Secondly, no attempt is made to correct history, in spite of the six billion Vulcans who have died. The new timeline created since the appearance of the Narada in 2233 persists beyond the year 2258.
The real-world reason for the persistence of the new timeline is that it serves to reboot the Star Trek franchise. The purpose of this article, however, is not the analysis of the reboot but of the implications of the fictional time travel and the new timeline created by it.
The depiction of time travel is not consistent in the long history of the Star Trek franchise. This becomes clear as we compare the consequences that a time travel to the past may have in the present. In very few instances the changes to the timeline do not affect the present. What happens in such a case is that the past incursion leads to exactly the history as everyone used to know it. The time travel then does not constitute an accident, it is predestined. We may go as far as saying that it was always meant to occur since the beginning of the universe. Something like this happens most obviously in TOS: "Assignment: Earth", TNG: "Time's Arrow", DS9: "Little Green Men" and VOY: "Time and Again". In these episodes the time travel enables itself instead of preventing itself. Clearly this is not the case in "Star Trek (2009)". The personal back stories, most clearly that of Kirk, are different than they used to be, and the looks or even the working principles of many pieces of technology have changed by the year 2258. The ultimate confirmation of the existence of a new timeline, aside from the explicit statements made by Spock, is that we know for sure that Vulcan still exists in year 2265, and that there are millions or rather billions of Vulcans in the 23rd and the 24th century (in case anyone should decide to fabricate theories that the new colony is christened "Vulcan" and later everyone pretends the catastrophe had never happened).
There are many more incidences in Star Trek where the characters' actions in the past change their own history. They notice the difference, either while still in the past or upon their return. The usually disastrous outcome of their trip is the incentive to correct it. One key issue of such forms of time travel is that our characters are protected against the alterations they cause. For instance, in TOS: "The City on the Edge of Forever" the past is altered in a way that the Federation does not exist any longer, and just the landing party on the planet as well as the time travelers McCoy, Spock and Kirk are still there, while the Enterprise simply vanishes from the orbit. Obviously the Guardian of Forever has safeguarded the further existence of these few people, although it is not explicitly mentioned in the episode. In a similar fashion, in DS9: "Past Tense" chroniton particles shield the Defiant in orbit (as well as the time travelers that beam down and end up in the past), while the civilization of 24th century Earth ceases to exist because of the death of Gabriel Bell in the 21st century. A similar effect may have protected Spock when he was still near the anomaly in the 24th century, while Nero was already wreaking havoc some 150 years earlier. The "protection against timeline changes" almost customarily happens under the assumption that otherwise the grandfather paradox would strike. You travel back to the past and do something to prevent the time travel from happening in the first place. Hence, to go back in time "safely", your memory and your plain existence has to be assured in some fashion.
All six mechanisms of how time travel could work logically are extensively described on my page on general considerations. There is just one more candidate for the principle that could apply in "Star Trek (2009)": the doubling theory as I dubbed it, which is more generally known as the many-worlds interpretation (in quantum physics) or the multiverse concept (in fiction). Screenplay writer Roberto Orci explicitly stated in an interview that he devised the time travel events in "Star Trek (2009)" to create a new universe that exists in parallel to the old TOS universe as we know it. Counting in the minor changes to the timeline as they were commonplace in nearly all time travel episodes, the seemingly continuous universe as we know it may be actually something like the 57th parallel timeline, assuming that there were 57 time travel events that altered history and of which each created a new universe that co-exists with all the previous ones. Looking back, however, there is very little evidence for the existence of co-existing timelines, much less for their creation through time travel.
The Mirror Universe from TOS: "Mirror, Mirror", from several DS9 episodes and from ENT: "In a Mirror, Darkly" is the first proof of the existence of a parallel universe. On the other hand, we never get to see the point of divergence. The Mirror Universe may not have been created by a time travel. For all we can imagine, it may have been severed from our own universe in its early days. For some reason, it maintains close ties to our universe, which we would not normally expect because of the second law of thermodynamics that requires the separate universes to diverge increasingly over time. The Mirror Universe is a one-off phenomenon. The somewhat parallel development to the main timeline is not only dubious in real science. It does not comply either with what happens in most time travel incidents, where the changes accumulate (the "butterfly effect"), rather than lead to the birth of visually (and genetically?) identical characters in both universes. Hence, the Mirror Universe can't really serve as a prototype for what happens in "Star Trek (2009)".
TNG: "Parallels" must be the favorite Trek episode of all the quantum physicists who favor the many-worlds interpretation. In simple terms, everything that may happen does actually happen, only in another universe. Each time a quantum transition happens and can lead to one of two results, we only rest in one of the two universes by chance. Over time the number of quantum universes will become practically infinite, much as it was depicted in "Parallels", when Wesley received 285,000 hails from Enterprises from other universes. It sounds like the weirdest idea ever and I don't understand how energy conservation may possibly work in the multiverse (I'm an engineer, not a physicist), but it is a seriously considered scientific concept. So how could this concept relate to the new movie? Is time travel covered by the many-worlds interpretation? Presupposing the many-worlds interpretation is true, a travel back in time would correspond to the return from a twig to the root of the current quantum universe. But altering something in the past would not mean that we simply travel up another existing branch of the quantum universe when we go forward again. The tree would have to grow again from there. This is of course very hypothetical, but I could imagine that, while the quantum doubling creates new universes "automatically" as time proceeds, going back in time may set off a different mechanism and may replace the whole tree of quantum universes from that point up. Who knows, there may be no "room" for another tree.
In my understanding, Star Trek's time travels never created parallel universes so far, they led to new timelines that replaced the old ones. Why else should the crews of Kirk, Picard, Sisko, Janeway and Archer have been hell-bent on fixing any time travel accident? Whenever characters returned from the past where they had caused a timeline change (technically a grandfather paradox that was either circumvented in some fashion or simply ignored story-wise), they wound up in the future of the new timeline, never in the old continuity. Furthermore, those who were left behind in the present suddenly found themselves in an altered universe, just as the Defiant in DS9: "Past Tense". If the Federation still existed in the old timeline, why didn't the ship remain there, why did it make the apparent transition to another universe in the first place? One notable exception is Spock in "Star Trek (2009)", but for all we know he could have been shielded much like the Enterprise in "First Contact" that followed the Borg sphere into the past. And the fact that the Defiant found its way into the altered universe might be explained away with the chroniton shielding technobabble, although it is still the more plausible theory that the old continuity simply doesn't exist any longer and was replaced all around the ship. (I hate to complicate this even more, but if anyone could return to or stay in their familiar future, it would just as well speak in favor of my course-of-time theory, one that I see as perfectly reasonable, although science fiction authors may deem this idea too boring compared to multiple universes.)
While it does not seem to apply in general, there are a few instances of conventional time travel (past incursion that is fixed in the end) where fans (including myself) would not exclude the parallel existence of timelines. One often-cited example is TNG: "Yesterday's Enterprise", in conjunction with the later episode "Redemption". As we all know, Tasha Yar died in TNG: "Skin of Evil". But the appearance of the Enterprise-C in "Yesterday's Enterprise", or rather her absence from the earlier year 2344, sets off a new timeline in which Tasha Yar is still alive in 2366. The Enterprise-C is sent back to 2344, together with Tasha. The old timeline is restored, at least as far as we can tell. In "Redemption" we learn from her daughter Sela that Tasha lived on in the year 2344. She did not simply disappear when the year 2366 was restored to normal. So does this mean that the intermediate timeline, in which Tasha comes to life again, persists just as Tasha herself? Not necessarily. As already mentioned people often seem to be protected by some <tech> effect against the annihilation of the timeline that they came from. This may have been the case with her as well, seeing how the ship went forth and back through a space anomaly. A quantum duplication could more universally explain away this and many other instances in Star Trek where a paradox should have happened, but was not visible. Definite evidence, however, is missing, and the implicit nature of the phenomenon of an altered past is almost always that there is only one history that has to be preserved. "Yesterday's Enterprise", the possibly best candidate for two parallel timelines, is ironically also among the episodes with the clearest statement that the (one) past has to be restored at any cost.
We may surmise that, if there should be the old future besides the altered one after the time travel event in spite of everything, there may be no easy way going there, no known method. Neither for the officers of the Defiant in "Past Tense" nor for the resurrected Tasha who wound up on Romulus in 2344. Simply reversing the method of time travel to the past may take anyone to the new future by default. There has to be some trick to reach the familiar, pre-incursion future if it still exists. Maybe in "Star Trek (2009)" Spock Prime knows more than the starship captains of the past 200 years and the viewers who have watched 40 years of Star Trek, and he has an idea how he could return to the year 2387 that he knows. It is not explicitly mentioned but his statement that he prefers to stay with the few remaining Vulcans may insinuate that the alternative would have been to return to his real origin. Or only to the year 2387 in the new continuity? In any case there is a small loophole. In a future movie or series the writers may decide to use it and either resurrect or at least visit the old continuity. But I doubt it. Or they have someone go back and stop Nero. But that is only wishful thinking of a fan who wants the old Trek or at least Vulcan back.
It is still possible that, while "normal" time travel replaces a timeline with a new one, the mysterious "Red Matter" is responsible not only for the creation of a black hole but also for the time travel and for the formation of a new universe in "Star Trek (2009)". In this case new universes were also created when Vulcan was destroyed and when Nero's ship was swallowed in the end, only that no one may have survived the transition to the new universe. This explanation attempt is far-fetched though, and it isn't really supported by the sequence of events and the dialogues, which gives us the impression that "Red Matter" is "only" responsible for the destructive effect of the black hole, the time travel being a side effect of the latter. On the other hand, "Red Matter" is a flawed concept anyway, so if we attribute some other inconsistencies to it, the black hole could make more sense again.
Alternatively, if we don't want to blame the "Red Matter", then the transition through the black hole may have involved some quantum uncertainty effect. This uncertainty may have thrown the Narada into a perhaps already existing parallel universe, and Spock, by a huge coincidence, into the very same universe. Prior to Nero's massive incursions, this parallel universe must have been close enough to the Prime Universe that he and his crew were not aware of the already existing possible difference and thought they had "only" traveled back in time. It may have been somewhat different though. This could excuse why the Kelvin and its crew does not quite look as we would imagine Starfleet ships of this era. Again, this idea is not really supported by the events and statements ("time continuum") in the movie, which insinuate that Nero and Spock are "normal" time travelers from the future, rather than from another universe.
In any case it remains to be said that the stance not to save Vulcan is unbecomingly fatalistic and highly unethical, considering that the science and technology to go back further than 2233 and stop the Narada would be readily available. At least Spock Prime should be familiar with half a dozen of time travel methods such as the slingshot effect, yet he chooses not to "cheat". -- Would it be "cheating" to prevent a disaster from happening that was never meant to happen? Neither in the Prime Universe nor in the new, parallel universe if it exists. The needs of the many outweigh the needs of the few, and the few people whose lives may not be as great in the original history as after the incursion definitely don't justify the sacrifice of the lives of six billion Vulcans, a complete species that was never meant to die. The possible existence of a parallel (old) universe in which the planet still exists is just a lame excuse for not doing anything. And it is in strong contradiction to what anyone from Archer to Janeway would have done to save the Vulcans. With the knowledge about the supernova in the 24th century, at least the planet Romulus has a perspective to live (even though, at the time of the movie, the Romulans wouldn't be exactly grateful for that information from their enemies).
Speaking of Romulans, what about Nero? He has been waiting for 25 years in the past just to take revenge on the man who attempted in vain to save his planet. Couldn't he and his crew have done something much more useful, such as going back to the 24th century, a few years before the disaster would happen, and warn their people in time? He and his men could have had a good time, regardless which version of the 24th century they returned to. But instead of that they waste 25 years preparing for an insane suicide mission.
If everything else fails, there should still be Daniels from the 31st century (from Enterprise) and the people from the 29th century (from Voyager) or pretty much every temporal police of every future era that can scan time while staying protected to repair the huge damage that has been done in "Star Trek (2009)". It is hard to believe that even these wouldn't do anything, while they were heavily involved in Voyager's time travel incidents and in Enterprise's Temporal Cold War, respectively. But perhaps they have actually fixed what they deem the main timeline, and what we see in "Star Trek (2009)" takes place in an abandoned branch of the time continuum, a parallel timeline indeed, but one that no one cares about any longer for some reason?
Classification: past incursion, leaving a persisting altered timeline
Addendum: DIS: Terra Firma I
The season 3 episode of Discovery retroactively explains that the Kelvin Timeline co-exists with the Prime Timeline. This sort of justifies, with a rationale along the lines of "We have another (better) universe in the trunk." why in "Star Trek (2009)" no one cares to undo the obvious damage inflicted by Nero. Even if something different happened in this story than in "classic" time travels, it is still mysterious why exclusively this one of all such incidents was identified from the outset as one that does not need or must not be fixed.
See Also
Credits
Some screen caps from TrekCore. Thanks to Jonathan H for the suggestion that "Red Matter" created a new universe and to Adam Smith who blames the uncertainty principle while traversing the black hole.