Time Travel in Star Trek: Enterprise (ENT)
"Temporal? - You've lost me." (Archer, ENT: "Broken Bow")
ENT: Broken Bow
The Suliban, being soldiers in what is called a "Temporal Cold War", are taking orders from a visitor from the distant future. We are never told who this visitor is and what exactly he wants to change in history. Anyway, so much is sure that the Suliban did get their genetic and technological improvements from the future. Without that, they would be not more evolved than humans. The question why we have never heard of the Suliban in TOS, TNG or DS9 may be answered in that Enterprise is causally set after the 24th century. So if the visitor, let's say from the 25th century, shows up, he is altering our whole familiar Star Trek history in a way that the Suliban should play a more important role, among many other possible consequences. This is, of course, a plot device that would allow *anything*.
Classification: past incursion, with unknown but possibly severe consequences
ENT: Cold Front
The disguised Silik saves Enterprise from being destroyed by a cascade reaction in the warp reactor, again acting on behalf of the mysterious visitor from the future that recruited the Suliban for his "Temporal Cold War". On the other hand, Daniels, an undercover agent allegedly from what will be the Federation in the 31st century, strives to stop Silik. So is Daniels taking into account that Enterprise may have to be destroyed to preserve history? He says no, although it seems unlikely that anything else could have saved the ship. The whole story is even more mysterious in the end than in the beginning, so it is virtually impossible to say if and how history was actually altered. Maybe we are looking at a predestined timeline in which Silik was always there to save the ship. His interference may have allowed further journeys of the ship and ultimately enabled the foundation of the Federation.
There are more interesting time travel aspects in this episode than before in Enterprise. First of all, it is noteworthy how Daniels arranges a time travel of Archer in which the captain relives his own past, as opposed to watching and perhaps meeting himself, as it was the case in almost all time travels before and also in Archer's second time travel to follow in the same episode. The only exception so far that I remember is in VOY: "Before and After" where Kes, without a viable explanation, always becomes her younger or older self. Archer, as if he had learned a lot more about time travel since "Broken Bow", poses the right question: If he presently is his own former self, who is on the ship in the future? Daniels replies that all this has not yet happened. This may be plausible if we establish a totally different view of time that Daniels has literally turned back the clock - in a way that the past is now the present for everyone in the universe. Everything is happening once again, with the exception of Archer who has, for some reasons, memories of a future that doesn't yet exist and, of course, Daniels himself who comes from the future. But how could a being without omnipotent forces accomplish that? The better explanation is that only Archer's consciousness, as opposed to his whole body, was transplanted. The question who will be on his ship in the future may not occur if we simply assume that Archer is transferred back from and forth to the very same instant in a way that he will never be absent. But then Daniels's statement about the future that doesn't yet exist wouldn't make much sense. And if it is possible to transfer Archer back and forth seamlessly, the accident in the course of his second time travel in the episode will be implausible, as will be shown later.
One point of criticism is that no effort is made in the first part of the episode to correct history, to avert the disaster in the planet's atmosphere in the first place - bearing in mind that Daniels explicitly states that it shouldn't have happened. With his knowledge about the device, Daniels could have easily transferred himself aboard Enterprise before it happened, and he could have told Archer about the accident in time. This may have saved thousands of lives, may have almost entirely repaired the timeline and may have been accomplished with much less risk than messing around in the already damaged timeline. If Daniels had not found out about the true reason of the accident because of insufficient data, it would still have been plausible that he tried to fix the timeline after the accident, but it became clear that he had the decisive hint that the Suliban were responsible. He even knew of the cloaked Suliban vessel and gave its coordinates to Archer. Even if Daniels wasn't sure about the exact cause, why didn't he simply recommend Archer not to visit the planet in the first place?
One remarkable fact is that Daniels and maybe Archer too don't only recognize the destroyed city of the 31st century, obviously San Francisco, but that Daniels even finds himself in the very same building after the time travel accident (he said he had just lunch in the other room when he appeared). This would mean that the building would have to be about 800 years old in either version of the 31st century, built in a time when the timeline didn't diverge so much yet. Amazingly, it looks much like it is supposed to be same building where Archer had his apartment just prior to his mission on Enterprise. The windows look much the same. Of course, this would be an incredible coincidence.
It is an interesting observation that, as already shown in Voyager's time travel episodes and mentioned in ENT: "Cold Front", Daniels is obviously able to scan time and determine what is supposed to have happened and what not. Like already the Relativity in VOY: "Relativity" he needs to be outside the normal space-time for that purpose, protected through the special suit he is wearing. This is also why he is the only survivor when Earth is devastated probably already a long time before the 31st century. Keeping in mind that Daniels as well as the unknown future guy who gives orders to the Suliban are isolated against changes in the timeline, the obvious paradoxes may be resolved to some extent.
Even if we accept the often cheesy conclusions of time travel episodes with their paradoxes in Star Trek, "Shockwave" is an exceptionally obvious example of flawed logic. When Archer appeared in the devastated 31st century at the end of the first part, it was obvious to me that it must have been because of some sort of "temporal accident", meaning that Daniels was aware what he was doing by taking him there, only someone or something was interfering with that, causing the catastrophe. But the second part made clear that it was alone Daniels's very fault. He should never have transferred Archer to the future. With Archer missing in the 22nd century, the Federation never came to existence. But this doesn't comply with the logic that Archer was supposed to stay there only temporarily and then return to the past to fulfill his mission (which clearly was Daniels's intention). We may see this as one of the few examples of predestination in Star Trek. In other words, Archer is taken to the 31st century, where he is stranded because the civilization of the future doesn't exist any more. But the civilization doesn't exist any more because Archer never got the chance to return to the 22nd century. The consequence is the reason.
But we still have to think a few steps further. Why does predestination apply for one case, whereas it evidently doesn't for other cases in the same episode and story arc? Daniels fails to give us an explanation or at least a hint. If we accept that inconsistency, we still have to wonder if it is a general mechanism of time travel that, if someone is removed from a time and relocated to the future, it would temporarily change the timeline in a way that it continues as if this person were forever absent from his time. Of course, if a historically important person were abducted this way, it would significantly alter history. Exactly this impression is created in the second part of "Shockwave", when Daniels becomes aware that the Federation was not founded because Archer was not there at the time. So the ultimate question must be why Daniels was so incredibly stupid to assume that taking Archer to his time could be done without danger. It seems he made that decision in a haste, as he was monitoring that Enterprise was surrounded by Suliban vessels. But Daniels would have had all time in the world to react to that. No matter how we try to justify it, it remains stupid.
Classification: multiple past incursions, partially with "biological" time travel, partially with predestination, partially corrected
ENT: Future Tense
A small pod with a dead pilot is found adrift, and it turns out to be one from the 31st century. Humans, Suliban and Tholians are struggling for the technology of the vessel. When Tucker finally manages to activate the emergency beacon found aboard, everything from the 31st century disappears, and is obviously taken back to its own time. The question with this episode is why no one from the 31st century, namely Daniels or one if his colleagues, bothered to track down and salvage the vessel earlier, to save its pilot and to avoid the past incursion in the first place. As Archer pointed out, they would have had any time they want to do that. Perhaps records were lost for some reason, or another faction in the Temporal Cold War undermined their efforts so that their allies, possibly the Suliban, could get their hands on the ship. This sounds somewhat plausible, considering that "Future Guy", who gives Silik his orders, is not capable to transfer any form of matter to the past.
Temporal disturbances of time repeating in a limited area is something we have seen before in TNG: "We'll Always Have Paris" on a smaller scale and in TNG: "Cause and Effect" on a larger scale. It is not really plausible, but consistent with the previous two occurrences, that the persons who relive time remember anything at all from a previous loop and just enough to keep it interesting.
Classification: past incursion, uncorrected
There is no time travel in the episode itself, but it shows the consequences of the time travel in "First Contact". The question occurs if the events of "First Contact" may have changed the timeline. Or more precisely, if Enterprise possibly takes place in a different timeline than TNG and much of Voyager. "Regeneration", however, has one (possibly ironical) hint against this notion. The closing remark that the subspace signal of the Borg would need until the 24th century to reach the Borg homeworld implies that the whole Borg timeline may be a causality loop -- the Borg became aware of Earth in the first place because they had traveled back in time. In a causality loop history would always remain the same, because it is predetermined that some day someone would travel back in time and create it in the first place. In other words, Enterprise and the rest of Star Trek remain in the same timeline if we go with this suggestion (unless another time travel in the course of the Temporal Cold War alters history).
Classification: possible predestination
Archer suffers from parasites that cause a cumulative loss of his short-term memory from the time when he was infected. It is discovered that these parasites exist outside space-time, and by destroying them in the present, they would also vanish in the past. An effect traveling backward through time is something we have seen three times before on Star Trek, as the concept of anti-time in TNG: "All Good Things", the "temporal bond" between Benjamin and Jake Sisko in DS9: "The Visitor" and the biotemporal effect in VOY: "Before and After". Only the anti-time idea was half-way plausible, whereas there was no serious attempt to explain the other two, semi-biological phenomena. The assumption from "Twilight", that something existing outside space-time would vanish no matter when in our time it is destroyed, actually makes some sense again -- and, on a side note, it is what might happen to the Prophets and Pah-wraiths in DS9 too. Still, there is the inevitable paradox, as the present was changed from an extinct future.
Classification: past incursion, remaining paradox
ENT: Carpenter Street
This is just the standard story of a past incursion that needs to be corrected. Persons and items that don't belong into a certain time may be marked with a tag, just like the beacon already seen in ENT: "Future Tense". The continuity to other time travel events, especially the ones including Daniels, may have been good. But we learn something very surprising that sheds a completely new light on temporal mechanics: The Xindi attack on Earth was not supposed to happen, and Daniels didn't notice that in time. He tells Archer that the outcome of an incursion needs time to reach the 31st century! This is unprecedented in Star Trek, where the effect on the future was always immediate, unless a person or ship was protected against changes in the timeline. Ironically, Daniels himself witnessed one of the most obvious examples of a sudden change in "Shockwave", where he said that he had no chance (or no time) to counteract it. And why should it take "some time"? If not immediately, we would expect the effect to take exactly 1000 years to travel from the year 2004 to the year 3004, according to what I call the course-of-time theory. Anyone living in the future would always be ahead of the changing timeline and would remain unaffected! The only half-way plausible explanation for this blatant inconsistency may be that there is something like a "shield" slowing down the change that would otherwise be immediate, forming some sort of temporal wave, a border between the new timeline behind it and the old one ahead. Or Daniels may have simply been lying...
As for Enterprise taking place in a different timeline than the rest of the Star Trek Universe (like it is frequently suggested by many fans), Daniels's hint that the incursion was not supposed to happen is no useful evidence. We have heard him and Braxton say things like that before. But if anything, it may have been used by the authors to invalidate Enterprise's third season using a reset button similar to the "Bobby in the shower" trick. Only that this would have established a precedence that may be referred to in attempts to excuse just any minor inconsistency as a very specific outcome of a time travel.
Classification: past incursion, corrected
ENT: Azati Prime
Archer finds himself on the Enterprise-J, 400 years into the future, where he meets Daniels. Unlike in "Shockwave", this time history is not messed up because Archer is missing in the past, although Daniels once again stresses the Captain's importance for the foundation of the Federation. We can only assume that Daniels has taken precautions this time. Still, there is no clue how he could possibly protect history in "Azati Prime", what he either failed to do or never bothered to do in "Shockwave".
Something we always have to wonder when Daniels appears is why he doesn't attempt more to preserve or restore his version of history. Once again, he would have had plenty of opportunities to initiate a dialogue between the Xindi and the Enterprise crew. On the other hand, we have to wait and see if this still happens...
We also learn in the episode that the Sphere Builders, knowing that they would be defeated by the Federation in the 26th century, told the Xindi that people from Earth would destroy their homeworld. This is a past incursion with the classic grandfather paradox.
Classification: past incursion with yet unknown outcome
The basic theme of this episode is the classic predestination paradox, as it has been featured a couple of times before on Star Trek, the most similar parallel being in DS9: "Children of Time". Here Enterprise 1 enters a subspace corridor from where the ship is tossed back 117 years into the past. But actually Enterprise 2 shows up before Enterprise 1 has a chance to enter the corridor in the first place. In other words, the effect exists prior to the cause. As usual in such cases, we have to wonder why Enterprise 2 wouldn't vanish immediately upon revealing itself to Enterprise 1. The mere knowledge about the future would almost inevitably change the future. If not disappear, Enterprise 2 should at least undergo significant changes, because everything that happens on Enterprise 1 will affect the ship, most obviously when they are fighting each other. But Lorian, the commander of E2, is apparently not concerned that he might destroy E1, and thereby his own ship too, not to mention Earth's future.
This is a significant difference in the time travel logic compared to "Children of Time". In "E²" no one assumes that Enterprise 2 would necessarily vanish once the situation is fixed and Enterprise 1 has not traveled to the past. On the contrary, Archer expects the other ship to follow them through the corridor. He may not know that much about time travel as his fellow captains 200 years later. In any case, this assumption conveniently avoids the problematic decision whether to save Enterprise 2 and the children born aboard in the last 117 years, or to save Enterprise 1 as it is in the 22nd century. Exactly this dilemma was made a big deal by Sisko in "Children of Time". The question whether Enterprise 2 really vanished (as we would expect from all we know about time travel, at least on Star Trek), or if the ship was simply destroyed by the aliens in the corridor, is solved much more skillfully than in the DS9 episode when E2 just stays behind without a trace. The best line of the whole episode falls to T'Pol:"Are you suggesting that the other Enterprise never existed? If you're right, then why would we remember them?" There's nothing to add.
Classification: "soft" predestined timeline with uncertain outcome
ENT: Zero Hour & Storm Front
Archer is on the Xindi weapon and is transferred to the year 1944, and so is Enterprise and its crew. The sudden temporal dislocation is just a lame excuse to let the brave crew fight against evil aliens and Nazis and then magically return to their own century. There is no reason why the destruction of Vosk's facility should reset the timeline, as the damage has already been done earlier in a logical order of events. The mention of Lenin's unscheduled assassination in 1916 as the original reason for the timeline mess even complicates the rationalization. We may believe that Vosk was responsible for that too, in order to facilitate his aid for the Nazis. But since Vosk was explicitly said to be about to depart for the future using the conduit, this would obviously change nothing in the past. It isn't evident either why Enterprise is abducted from a time when the ship is battered and barely operational and its crew tired. Hardly anything makes sense here. Not the slightest attempt is made to explain the situation, the blunt remark "That's beyond your comprehension" is meant to suffice. As if blurring and even denying the problems would make everything more plausible.
But on a more interesting note, we see Daniels suffer from some sort of illness that makes parts of his body age at different speeds. This is a similar effect as in TNG: "Timescape". Moreover, could this be the nature of the temporal narcosis mentioned in VOY: "Relativity"?
Classification: past incursion, corrected
ENT: In a Mirror, Darkly
Only the Mirror Universe is concerned by the time travel of the USS Defiant of the 2260s of our universe to the 2150s of the Mirror Universe. The Mirror Universe always keeps strange ties with our universe, dating back at least to the time of Zefram Cochrane, as seen in the episode's teaser. Despite the radically different historical events, the characters as well as the technology are essentially the same as in the corresponding era of our universe. "In a Mirror, Darkly" may have changed that, by introducing a ship class that is 100 years ahead of its time. Or it had no such impact, as the future ship may have been destroyed soon after the episode, leaving behind no technology or only plans in that time. Or the strange entanglement gradually corrects the mirror timeline, with the result that the 2260s look just as in our universe, and just as in TOS: "Mirror, Mirror". In the latter case there would be something like predestination, but as an inherent principle of the Mirror Universe and not as a phenomenon of time travel.
Classification: past incursion, with unknown but possibly severe consequences in the Mirror Universe