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Time Travel in Star Trek: The Next Generation (TNG)

"Let's make sure that history never forgets the name... Enterprise." (Capt. Picard, TNG: "Yesterday's Enterprise")

The Series

TNG: We'll Always Have Paris This episode is full of "small" paradoxes where the characters encounter themselves in moments that are only a few seconds or minutes in the past or the future. The problem is basically the same as with the grandfather paradox, although the impact is of course less severe.
Classification: random time shifts, without visible consequences

TNG: Time Squared In this episode Picard 2 is the only one to survive the explosion of the Enterprise and he is thrown six hours to the past together with his shuttlepod. Aboard the still existing Enterprise in the past, Picard 2 suffers from a severe shock and cannot remember anything. Moreover, the shuttle's computer data cannot be read out. This is obviously a trick to keep the situation obscure. The shown effects are doubtful with regard to other time travel episodes. The difficulty with the shuttle's energy signature may be rationalized with some technobabble. Picard 2's respective physical and mental condition, however, seems to be directly related to the current time, as if there were a temporal signature of his organism that makes him feel better the closer he is to the time of his departure. There is no such effect in other episodes, only a weak similarity to TOS: "All Our Yesterdays".

It was ethically highly questionable for the present Picard 1 to kill his unlucky alter ego from the future. It would just have been necessary to hold him back, since "the cycle must end", as Picard 1 himself noted. After changing the timeline in this direction, Picard 2 would have disappeared anyway in the same manner the shuttle disappeared. There is an obvious paradox when the Enterprise does not explode, since in this case there is no Picard to travel back in time and warn the Enterprise.
Classification: broken predestined timeline ("causality loop")

TNG: Yesterday's Enterprise When the Enterprise-C appears from the space-time rift, the timeline from the instant of its departure in the past to the present is immediately switched. It can be supposed that the Klingons regarded the disappearance of the Enterprise-C as cowardice which finally led to the war timeline. Of course the Enterprise-D crew, as almost all other beings in the galaxy, are unaware of the change, even as Worf is replaced by Tasha. It remains a mystery how Guinan is able to perceive the old timeline which has not been "simply" erased from biological and computer memories, but has actually never existed. No one would expect a biological entity to have such a supernatural ability which is absolutely useless for its normal life. One would rather suppose that beings such as Q who move in more than three dimensions can perceive and also manipulate timelines. Maybe Guinan is not the humanoid she appears to be.

Apart from the temporal sequence, there is also a logical sequence of events.

1. The Enterprise-C defends the Klingon outpost and is finally destroyed, which is honored by the Klingons (timeline 1).

2. The Enterprise-C is "pulled" into the future (i.e. 2367) prior to being destroyed, which infuriates the Klingons and creates the war timeline 2. The space-time rift is not a static phenomenon, but originates at event 2, since until then the old timeline 1 definitely existed.

3. The Enterprise-C is "pushed" into the past again which recovers event 1, but not exactly, since Tasha is aboard the Enterprise-C.

4. The Enterprise-C defends the Klingon outpost and is finally destroyed which is honored by the Klingons. Some crew members, among them Tasha, are "saved" by the Romulans, only to be killed later on. However, Tasha gives birth to her daughter Sela, who will appear later in TNG (timeline 3).

The problem with this episode is the fact that the temporary timeline 2 should have been eliminated by sending back the Enterprise-C to the past. This would not allow Tasha to stay aboard the Enterprise-C, she would simply disappear at the instant when the future is changed again, and Sela could never exist. Vice versa, Captain Garrett, who died in a never existing future, would come to life again (for a short time). This is an obvious paradox.
Classification: past incursion caused by accidental travel to the future, remaining paradox (Tasha and Sela)

TNG: Captain's Holiday Time travel is only a secondary aspect of the story, although the Tox Uthat is assumed to come from the future. However, this is one of the few episodes where a predestined timeline is established, since the two Vorgon time travelers obviously anticipated that Picard would destroy the Tox Uthat.
Classification: predestined past incursion ("causality loop")

TNG: A Matter of Time No paradox occurs in the episode itself. However, by leaving his own time which is in fact the 22nd century, Rasmussen has probably already altered history. Besides, it does not become clear why Rasmussen, who has a timeship from the 26th century, chose the less advanced 24th century to steal technical equipment. Moreover, for an ordinary thief he seems to be too well prepared, since he knows or pretends to know a lot of details about the Enterprise. There should have been much easier ways for him to get valuable equipment than on the well-guarded starship.
Classification: intentional past/future incursion, without visible consequences

TNG: Cause and Effect This episode features two different kinds of time travel. First, the U.S.S. Bozeman unintentionally travels 90 years to the future, just to collide with the Enterprise. Second, the Enterprise is caught in some kind of time loop. Every time the Enterprise is destroyed, the present time for ship and crew and probably the surrounding space region returns to an instant some time before the ship's destruction from an external viewpoint. In other words, the Enterprise and her crew do not travel back in time, but time itself is not continuous within a small region of space. This is corroborated by the statement that the Federation time signal is 17.4 days ahead at the end of the episode, meaning that the Enterprise has stayed in the time loop for this long as seen from an external observer.

The phenomena in this episode are not really put in plain words. The starting point of the events seems to be a space-time rift, potentially similar to the one in TNG: "Yesterday's Enterprise". The Bozeman is pushed or pulled into the future through this rift where is almost immediately collides with the Enterprise. The explosion of the Enterprise, probably in connection with the surrounding space-time distortion, causes the time reset. We do not know if the Bozeman explodes as well or is directly affected by the destruction of the Enterprise. However, it is obvious that the Soyuz-class ship is caught in the time loop as well, since the collision occurs repeatedly. Each time the Enterprise is restored to the state that was a few hours ago, and the same must apply to the rest of the space region. Otherwise, in the second and following laps the crew would have registered discontinuities in sensor measurements. We can assume that a Federation time signal is not continuously received, although this was possible in TOS: "The Naked Time". However, in any case the changes of remote constellations are definitely measurable and should have revealed the time reset. Since the Bozeman was not in the respective space region some hours ago, the ship is thrown back 90 years after each explosion; only this way it can emerge from the rift each time.

The story is substantially consistent if we accept the unlikely fact that humanoids have a built-in sixth sense for temporal discontinuities (déjà vu) that Data as well as the advanced subspace-physics based equipment of the Enterprise do not detect. There is no paradox, since the repeated collisions and explosions actually happened. Still, the chance of a collision of the two starships is literally astronomical, even if we take into account that the Enterprise is somehow attracted by the space-time distortion.
Classification: broken causality loop

TNG: Time's Arrow There are two obvious indications of a predestined timeline in this episode. First, Data's head is found in the cave before Data actually travels back to the past and loses his head. Second, Guinan pretends to know Picard for a long time, which is confirmed "later" when Picard meets her in the past. If we assume that back in the past the crew involuntarily create exactly the timeline that has always existed, this episode is self-consistent. Moreover, complicated explanations of timelines are not necessary, since there is only one timeline. Nevertheless, predestination remains hard to accept. What if Data had stayed away from the scene under all circumstances, in order to avert his time travel? Who could have hindered him?
Classification: predestined past incursion ("causality loop")

TNG: Tapestry Picard is given a second chance to avoid the confrontation with the Nausicaans in the course of which he lost his natural heart when Q sends him back to his early days in Starfleet, briefly prior to the incident. It is not evident if Picard is actually back in the past or if it is only a holodeck-like simulation. Q's promise that Picard can change his own history without affecting other people is odd in any case. Furthermore, Picard perceives himself as the aged captain, while everyone else sees the young Ensign Picard. At the end of the episode, when Picard is revived (for which he is rather indebted to Beverly than to Q), it is still not clear whether his experiences in the past were true. We might tend to believe Q, who has never been so honest and sympathetic than in this episode and will never be again. In this case, the past has been slightly changed, taking into account Picard's short affair with his nice crewmate Marta.

Besides, the authors missed a great opportunity in connection with the TNG episode "Bloodlines", where Dai Mon Bok alters a boy genetically so that he appears to be Picard's son. The boy, however, could have been Picard's and Marta's real son and this could have proved that Picard really traveled to the past. Furthermore, a new storyline with the father-mother-son relationship could have emerged, if it had not been shortly before the end of the series.
Classification: multiple intentional past incursions, without visible consequences

TNG: Timescape This episode features various time levels in which time proceeds at different speeds. The time on and around the Enterprise and the Romulan Warbird almost stands still relative to the time experienced by Picard, Deanna, Geordi and Data in the runabout. The concept and effect of time levels is similar as in TOS: "Wink of an Eye", however, the explanation is substantially different in the TNG episode. Here, the time levels are a physical phenomenon, and the effects of interaction between different time levels have to be considered on this level. There should be physical as well as biological problems for a character entering another time level. Yet, only the latter ones have are partially shown in the episode.

Further investigating the implications, it turns out that any interaction with a significantly different time level is virtually impossible. Firstly, light coming from a slower time level is shifted to infrared and also its intensity is significantly reduced, so even Geordi would hardly be able to see anything. This is due to the simple fact that one corresponding oscillation period is much longer in the slow time level than in the fast level. Secondly, the same applies to atomic movements, so the temperature would be virtually 0K for persons from the fast time level, and of course extremely uncomfortable. Thirdly, it is doubtful whether it is possible to touch or move objects in the slow time level or to breathe the "slow" air, let alone to cope with their low temperatures. Finally, even if interaction is possible, the slow computer should need a lot of time until anything is displayed. The writers could have avoided at least the latter inconsistency by somewhat slowing down the LCARS response times.
Classification: different time levels

TNG: Parallels This is one of the most fascinating Star Trek stories ever. It focuses on parallel realities, while the time travel at the end of the episode is only a secondary aspect. The time travel probably serves to return to the original timeline in "our" universe that would otherwise have been altered by Worf's temporary absence, or another Worf's presence.
Classification: travel to another reality and back in time, without visible consequences

TNG: Firstborn We get no idea if and how old Alexander's appearance in the past would affect his own time and himself. The grandfather paradox is quite evident, considering that young Alexander would be warned and probably wouldn't travel back in time in his later years.
Classification: past incursion, with unknown consequences

TNG: All Good Things Q is well-known for his fancies, and of course it is him who he arranges the weirdest time travel of Star Trek so far. Maybe he takes pleasure in sending Picard on time travels since TNG: "Tapestry". Firstly, three different times in the past, the present and the future are involved, and Q arbitrarily transfers Picard from one time to another. Secondly, Picard is transferred into himself, i.e. he replaces his alter ego in the past and the future. In a "normal" time travel there would be two simultaneous Picards. Thirdly, his actions in the past do not have any bearing on the future, the three times are isolated from each other in respect of the normal forward movement of time. Finally, vice versa, the captain's actions in the future do affect the past. It seems that Q employs any possible trick to bring about the anti-time reaction that destroys all mankind in the past, only to blame Picard for it. Picard is only a marionette in Q's highly unfair fancy, however, despite all off Q's attempted deception, the best Star Trek captain ever does his job.

The fact that the Enterprise is destroyed in "Star Trek VII: Generations" might be a sign that the TNG episode does not describe an actual future, but only a future in Q's imagination. However, in DS9: "The Visitor" another possible future is shown, and the future Defiant crew wear the same uniforms and badges as on the future Enterprise and Pasteur. Apart from the obvious budget savings, this is a sign that Q's future is not inevitably the real future, but at least a realistic one.
Classification: multiple travels to multiple times, without visible consequences

The Movies

Star Trek VII: Generations The movie features the Nexus, a phenomenon that allows either to stay in the wonderful world inside or to travel anywhere any time. In other words, the Nexus can do everything. This quality is certainly not beneficial as far as the story is concerned, since it leaves too many options and too many questions. According to the Star Trek Encyclopedia II, Soran was only briefly inside the Nexus in 2293 until he was "rescued" by the Enterprise-B transporter beam. This assumption makes more sense than the theory that the El-Aurians were expelled from the Nexus by the Borg. Exactly the same as to Soran must apply to Guinan. However, while Soran is definitely outside the Nexus when Picard meets Kirk, there is a representation of Guinan left in the Nexus and able to talk to Picard.

Picard and Kirk probably chose the worst possible instant to leave the Nexus and return to reality when Soran already had his finger on the launch button. If it is true that the two could have traveled anywhere any time, they could have returned e.g. to the Amargosa Observatory. Captain Picard probably considered possible effects on the timeline, however, either he wanted to prevent the destruction of the inhabited solar system under all circumstances or not. In particular, Kirk could have chosen a better time to return to reality. What if Kirk had gone back to his own time and probably changed history?

In this movie a paradox does not occur, because the Nexus probably works as a kind of buffer between the timelines. The Nexus is obviously a domain outside of our space-time, and is therefore not affected by changes in our universe. So the old timeline in which the Veridian system and the Enterprise saucer are destroyed ceases to exist, however, Picard is nevertheless always present in the Nexus (like Guinan), and so he is able to leave the Nexus and fight Soran in the new timeline.
Classification: past incursion to change history, successful

Star Trek VIII: First Contact When the Borg alter history by sabotaging Cochrane's first warp flight in 2063, the Enterprise-E is protected from the change, since the ship is already in the vortex that leads back in time. So far, the authors have learned from errors in the past when such a phenomenon remained unexplained. When the Enterprise-E arrives in the year 2063, it is already too late to prevent the formation of a new timeline, since the Borg have begun to shoot at the launch site and have killed a number of people that might have been important for history. Picard's first idea should have been to travel back about one more day (using the slingshot effect) and immediately destroy the Borg sphere as soon as it arrives. Even without the Borg's attempt to capture the Enterprise, the success of the actual efforts to correct history is questionable. It seems to have worked though, and the Federation is the same as before, or has only imperceptibly changed. We might speculate that "First Contact" features a predestination since Riker quotes the future Cochrane and Cochrane might have the quote from Riker (not to mention that Cochrane may have been inspired to name the first Warp-5 ship "Enterprise").

However, why did Geordi recreate the Borg vortex to return to the future, instead of choosing the good old slingshot effect, which is even possible with a primitive Bird-of-Prey? It is possible that the missing deflector didn't allow to go to warp, but it was never mentioned as being so crucial, so it must have been obvious to the crew that the Borg vortex was the only or the best option to go back.

A problem arises with regard to VOY: "The Year of Hell" where Seven of Nine knows about the Phoenix because "the Borg were present during those events". The first explanation could be that some Borg were still alive, or at least their subspace transmitters were functional when the Enterprise arrived back in the 24th century, and they contacted the collective. Secondly, they could have used temporal transmitters such as in VOY: "Timeless". Thirdly, although the modification of the sensor dish failed, a conventional subspace signal could have made it to Borg territory in the 21st century. However, in the two latter cases the Borg would have been warned, and this should have altered the timeline...
Classification: past incursion to change history, corrected

Proceed to Time Travel in DS9

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	Last modified: 02.04.08
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