I understand most of Walter's plan to defeat the Observers in the season finale. I even understand why someone must go with Michael to the year 2167, in order to make sure the boy reaches and convinces the scientists in Oslo. Thematically, it makes a lot of sense for Walter to sacrifice himself for the greater good, redeeming himself after almost destroying two universes (among other things) due to his past selfishness.

But why does he claim "Nature abhors a paradox", and makes it seem as if his staying in the current timeline would somehow create some contradiction? Everyone else on the Fringe team fought the Observers too -- Peter Bishop in particular dangerously so -- so why won't their existence create a paradox as well?

What paradox is Walter talking about? Or is he simply saying something he thinks Peter will believe, but which isn't actually true?

  • I'd touched on the paradox in my answer for How could Walter send Peter the letter in the last episode?, but I'm not sure it answers this question.
    – Izkata
    Aug 30, 2013 at 1:42
  • @Izkata Yes, I saw (and upvoted!) your answer, but I don't think it answers this question. Instead your answer is more about how Walter managed to send the letter; but it doesn't explain what the actual paradox was!
    – Andres F.
    Aug 30, 2013 at 1:45
  • @Izkata My own theory is that Walter made the paradox thing up as a way of convincing himself and Peter. But maybe it makes sense and I simply didn't understand it.
    – Andres F.
    Aug 30, 2013 at 1:48
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    To be perfectly honest, I also thought he made it up, due to his willingness to switch places with Donald, but there've also been hints in other time travel episodes that such paradoxes can happen in the Fringe universe...
    – Izkata
    Aug 30, 2013 at 2:09

9 Answers 9


Truthfully, the entire show is a paradox.

First, under the old adage of Back to the Future, Walter and Michael going to the future won't change anything as they'll be going into the future of the alternate timeline. A timeline in which the observers have control, so who's to say that the creation of them will occur in Oslo in 2167, making the observers paradoxes as well as they have irreparably changed the timeline for the worst.

Also, the main point, if Walter and Michael go into the future and stop the creation of Observers, then the entire plot of the show would cease to exist. The event that started the whole plot, September being in the lab when Walternate nearly made the discovery for the cure, would not happen. Had Walternate seen he made the discovery, he would've been able to cure Peter, negating the reason for Walter to cross over to the other universe in the first place. The crossing over of which caused the universes to decay, causing the Fringe events.

Therefore, without the Observers there is no Fringe, and the timeline in which Peter and Olivia meet no longer exists. The whole show is a paradox; just a never ending series of Catch 22s. Not to insult the show, I love the show. Just like to point out that the story folds in on itself, making it from a logical standpoint, in terms of the space time continuum, impossible.

  • I think Walter would still have crossed over eventually, just not to kidnap Peter. So, it is still possible that many of the events would still take place, but I find it unlikely that Peter would have met Olivia. Perhaps he would have met Fauxlivia. May 6, 2014 at 13:33

I don't think that Walter traveling to 2167 with Michael erased the Observers. Instead the knowledge of a different way to address human evolution would have created a breed of Observers more similar to Michael, ones with emotions and that are capable of empathy.

As a result, the "new" Observers would preserve the past by recreating the conditions for Walternate to be distracted when finding a cure for Peter, etc.


I think the paradox is like this: Walter had made the plan with September before the invasion. Walter was the only one of the Fringe team with knowledge of the invasion before it happened. If Walter had remained in the timeline after the non-invasion, he would have had to have knowledge of the invasion and the plan. However, the other Fringe team members could go on living their lives not knowing anything about any Observers or invasions.

I also think that only events after the day of the invasion have to be "consistent", because time was only "reset" from that day and onward.

  • 1
    I get Olivia from the rewritten timeline not knowing about the Observers, but Peter? Peter's life was saved by September when he was a boy, in the original timeline. Even if he knows nothing of the invasion, he must know about the Observers. Wouldn't that be a paradox as well?
    – Andres F.
    Sep 30, 2013 at 1:09
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    Peter is a parodox anyway, because he's from a different timeline. The writers clearly feel that he doesn't have to make sense.He "knew" about September saving him in a reality that he wasn't saved, and presumably his body as a boy was still at the bottom of Reiden Lake.
    – ike
    Sep 30, 2013 at 13:32
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    I should also point out that Olivia's memories came from Peter in a poorly understood process and are an extension of his paradox.
    – ike
    Oct 1, 2013 at 14:57
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    Poorly understood indeed ;) Like Olivia says, her memories cannot come from Peter because she remembers stuff he never knew! But yes, I consider her part of the paradox as well.
    – Andres F.
    Oct 1, 2013 at 16:09
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    @ike: Concerning Olivia: True, explaining it like that makes sense. Though I'd consider the "just like" with care - Olivia brought Peter into a timeline where he didn't exist; Peter essentially killed Olivia of that timeline to replace her with the Olivia he knew. And indeed, not everything that was said on screen has to be true - I had considered September's "She is your Olivia." and "There is no scientific explanation." to be rather questionable statements, as well. Jan 7, 2014 at 17:28

When Walter traveled to 2167, and assuming he was successful in introducing Michael to Oslo, he effectively restarted the timeline from 2167 on and eliminated the creation of the Observers. Thus stopping them from taking over in 2014. This would have eliminated the need for Walter to create the plan for time traveling. This would create a paradox because how could Walter continue to exist from 2014 on and the Observers not come back in time. This would also mean that Walter could not exist in 2167 because he would not travel forward in time. You could not have a Walter that exists both in 2014 until the end of his days and exist later in time in 2167. His continued presence in 2167 implies that a Walter in the past would need to vanish and the point would have to be prior to the catalyst of the whole incident - the arrival date of all the Observers. This does not disqualify the possibility of Walter traveling back in time from 2167 should he chose to do so.

  • 1
    But why would Walter need to travel to 2167 to begin with? Why not send Donald with Michael, as indeed Donald convinced him to do? If Donald was an option, then Walter's existence past 2014 in itself wasn't a paradox! However, Walter tells Peter he must go himself or the paradox will manifest. How can that be, if Donald was also an option?
    – Andres F.
    Oct 26, 2013 at 22:03
  • "how could Walter continue to exist from 2014 on" - why shouldn't he exist from 2014 on? Without the Observers, nothing special would happen in 2014 ... and with the Observers, Walter would continue being around in 2014 just as well. The only Walter that could possibly disappear should be the one in 2167, along with the boy, because the preconditions for their arrival there (the time travel from 2026) would have changed. Where is the connection between the post-invasion Walter in 2167 and the non-invasion Walter in 2014? The two are evidently from two different timelines. Jan 7, 2014 at 13:03
  • I think your concluding statement about Walter's possibility to travel back is interesting; I was thinking exactly the same (even though I think I remember Walter saying otherwise on his good-bye video). Somehow, this makes his so-called "sacrifice" even less of a sacrifice than what it would have been had he just departed on a one-way trip to 2167. Jan 7, 2014 at 13:07

You see, I thought the whole paradox thing had to do with the fact that Walter would have to live out the rest of his life from the year 2167 on, since there was no way for him to travel back to his own time. I assumed this was the paradox because it doesn't make sense for a person to exist in two different points in time. This theory actually made me even more confused because I thought it would make more sense for Walter to inexplicably disappear at the point where he would have actually went through the wormhole and not 2014.

  • Hmm, I understood that he had to travel to 2167 in order to avoid the paradox! Not that the time travel itself caused the paradox.
    – Andres F.
    Oct 8, 2013 at 16:14
  • @AndresF.: Isn't the time travel itself a part of the paradox? After all, the result of the time travel (Walter's and the boy's arrival in 2167) is the very reason why the time travel will not take place in the first place (as there is no Observer invasion that would make it necessary). Jan 7, 2014 at 13:14

I think that is a perfect paradox. Since the beginning of the show we saw that Fringe event present itself as events that were possible because Walter have conceived them even when he didn't remember that, are things that other scientist made possible based on his research. When September describes the plan he says that the scientist in the future are in Noruega. Long before, Walter invented A poem to help him remember that said "hard artichokes rarely keep , norwegian elephants , singapore sleep" That got me thinking what could possibly do Walter in the future? In the episode that we saw his lab assistant talk to him she says: - the Walter that you were before is not gone , You have been him longer then you have been yourself. And he says That he won't become that person, because he has Peter to keep him grounded. But in the future he doesn't have Peter, neither Nina to remove the parts of his brain. So I believe that the scientist from the future who created the observers where lead by him. Without knowing what he was doing. Like happened all along the show, he always did research that in the end was used for developing new creatures or weapons or other things. In every good times travel story, you usually have the protagonist trying to stop the events, and at the very last minute realize that he really caused what he was trying to prevent.
Maybe here is the same... So, now we know that the observers didn't invaid in 2015, but they exist, because September interrupted Walternative from finding the cure for Peter, and then he saved Peter and Walter in the lake. So, if they someday continue this amazing show, I think that we are going to find out how Walter create the Observers and how they changed the time line, so they don't invaid in 2015. And how he travels back in time to the past and bury the machine on the ground how he meets the first Sam Weiss and give him the mission to take care of the machine and the parts of the plan. (sorry for my english, I'm still learning)

  • Come full circle Jan 26, 2017 at 1:36
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    Hi there. This is a good start, but I'm having trouble finding your answer. What is the paradox here? Jan 26, 2017 at 1:38

Well, he explained to Peter that himself and the boy observer will became a Paradox, because of what they did (changing time, erasing the observers). So assuming that's the way the paradox works, by living him over there, I believe that maybe the whole show was a continuation from that event: because Walter was send to the future without Peter or any sport system to keep him from becoming only interested into science, he develope ways to improve the human brain which results in the Observers. In that journey he realizes things that leads him to the past to bury the machine. Maybe he even realizes that if the observers doesn't exist his son will not grow old, and never will meet Olivia or have Etta. Or maybe not, maybe it all just happened that way, without he fully understanding it. But at the end, Walter told Peter that he wouldn't change the time they had together "for the world". So... I know that is a long shot, but it's possible that if they continue the story, they have to explain how everything was possible, without the observers.

  • Which I think is not. The only way they all exist and lived the life that we saw, is if the observers exist. Jan 27, 2017 at 2:58

We have four overt non-Observer time travel acts in Fringe on which to base some conclusion. This is not a lot to go on. The difficulty is that we as viewers have access to more information than most of the characters. Most complaints of inconsistency come from viewers unable to reconcile their godlike view of the Fringe universe with the events as the characters in the universe understand them.

If the Oslo doctor basically created the Observers, then the invasion would have happened. The latest possible point to avoid this future is when the invasion would have actually happened; afterwards, the Observers would guarantee it happened, so this is the last possible point to change anything. For this invasion to not happen, someone must stop the doctor. Walter stopped the doctor. So Walter cannot both exist in the past and arrive in the future. So Walter disappeared. It would be an open question whether Olivia and Peter would remember anything about Observers. I would guess "no." Either the past, or their memories of the past, would not contain Observers at all; or, if they did, they would not be the Observers sent back for the illicit purpose of staging an invasion. Some evidence of this is the fact that the Peter-less timeline had Olivia's past be different because e.g. Peter wasn't there in the field as a child, which led to a different outcome for her stepfather and her emotional stability. I would note that I do not believe September (Donald) going through to the doctor would have erased the observers. Possibly that was tried in several loops we never see. Donald could not exist in a future and a past which didn't lead to that future. Walter could—and he could bring the Observer child with him—but only if he disappeared. When Walter disappears, to others the Observer child seems uncaused, but he isn't uncaused, Walter is there, though he reports on a past that doesn't exist (which is why he doesn't exist in the past that does). If Donald attempted to bring the Observer child through, then either both Donald and the child would be uncaused or Donald could not succeed in the plan and the whole loop would continue (it appears the child knows this already).

A similar thing happened when Peter turned on the machine, linking universes. Peter used it to destroy the alternate universe. In the future, Peter found out this would destroy both universes. They built the machine and sent it back in time. But the device they built allowed Peter using it to see the very future they hoped to avoid. In doing so, Peter avoided that fate. Peter could not both be in the future where the machine is created and in a present where the machine never destroyed universes, so Peter was erased at the latest possible moment, namely, when he turned on the machine and made the bridge. That is, we the viewers know this is the cause of the machine. In fact in the timeline itself Peter died in the past. The confusion is that we were at a particular point in time when the timeline was altered. We the viewers exist outside of time in Fringe so our past is not overwritten.

So the paradox is resolved: people cannot exist in the future and in a past that didn't lead to that future. (Which is why the plan to defeat the Observers works.) In both cases, one person in particular was responsible for the timeline being averted and so that person had to cease to exist. These people's disappearances appear necessary so that there are no uncaused events: the existence of September's son, and the existence of the machine. These only appear uncaused for people on the altered timeline. The original creation of the machine itself is likely pinched off from understanding. I would guess that even without the machine the universe was being destroyed, and a future Walter built that machine in order to destroy the alternate universe before it could cause a collapse, but that still caused a collapse and had to be adjusted again, leaving the machine appear totally uncaused. (So long as the universe was going to collapse, Peter and Walter would build the machine, so there was nothing to "fix" and Peter would continue to exist.) But it is only uncaused because we're in 20XX and not deep in the past to talk to "The First People" who could report the cause to us. (And the characters are not in the future where Walter talks to the doctor to speak to him in order to know the cause of the Observer child.)

And this is why Peter disappeared, but not the First People, because the First People were necessary for any future to exist but due to the time loop caused by the machine itself the only future Peter could exist in was one which the machine would destroy the future. If that future didn't happen, Peter couldn't exist, since Peter was the cause of that future. And that future was going to happen because of Olivia and Peter's relationship. And that happened because Peter was in this universe. So Peter in fact died at the lake.

Analogy: it's like you put a number in your calculator, and hit cosine over and over. Regardless of where you start, you end up at the same number. Eventually you can't even tell what number you started with anymore. In the end this fixed point appears uncaused and the original number disappeared. Sometimes in Fringe we're stuck with the consequences of this directly, sometimes we get to see the last iteration before the fixed point converges. Truly, we don't know how many plans Walter and September tried before the fixed point of Walter going to the future was found. On some loops they could have tried other time travel plots, perhaps one of them leading to Bell's discovery of the stasis runes for example (another truly unexplained point, even to September).

At certain key points it seems there is only one way for the future to continue; if it is stuck in a loop, iterations will continue until the future exists. There is always a future, therefore the timeline will always converge to a future. We are lucky in Fringe to see the convergence, rather than only what happens after the convergence.

Another point in favor of this idea is the episode where Peter Weller tries to save his lover, and to us watching appears to actually cause the very death he hoped to avert. Given the way we see time travel operate with regards to Peter and Walter, it's likely that Alistair (Weller) had not in fact caused her to die originally, but Alistair could not both invent time travel and live on with her, so he had to be erased, and the latest possible moment for that was to actually have him cause the accident on the "last" iteration, leaving a seemingly uncaused death (but only because Alistair was not there to explain it to the characters).

Finally we have the episode where Raymond Green is trying to save his wife using her mathematical equations to build a time machine. The act of him doing so was causing a time bubble to destroy the timeline, presumably because the technology in question was not the "right" way to time travel. Because the overall timeline was not altered there was no inconsistency and there was nothing to repair. Instead the fixed point was merely the apparently uncaused creation of the time machine itself (since the notebook had no legible equations in it). But maintaining the uncaused-cause of this notebook actually required no one exist in multiple places (Raymond and Peter were "safe" knowing the origin of the machine), so the overall consequence of this fixed point didn't have anyone disappear.


It means nature simply dislikes it. Naturally, it will adjust its course to correct itself. It'll find a way to correct itself eventually.

This statement is taken from an erased timeline in which he's just making a case of resetting time (again this was a wrong choice made by Peter). Now, whenever there's a time travel concept there has to be paradoxes. Resetting the time is in itself a paradox. But that doesn't mean if we're dealing with time travel we let it go unanswered.

Remember, when Olivia was murdered by Walternate and Walter tells Peter afterwards he knows how to make all this correct cheating rules of the game? i.e., by creating a paradox and allowing other players to play their role and make adjustments within the paradox. He said he didn't have any other choice but to make same decision again and again i.e., send the device back millions of years always in the past.

However, he has an option to alter the device to make Peter realize what'd happen if he takes a bad decision therefore making him take a different decision (Correct one hopefully). It must have taken him a number of turns until Peter realized what needs to be done. Which Peter did hence wrote another timeline where two universes are working together.

Now apply this same thing on last episode you're asking about. He said he and the boy will become a paradox. In the episode of (Walternate killing Olivia) he sent the device back to past which was a paradox meaning if Walter sends it back someone has to keep sending it back always i.e., an impossible situation. In the last episode, however, he goes into the future to prevent an event from happening. Someone has to keep on going to the future to keep the paradox situation from happening and allow universe to heal itself. It could not be September or just Michael only it has to be someone belonging to this timeline.

Now, look closely Walter must have sent the device back in the past again because he's succeeded in helping Peter take right decision. The universe corrected its course when Peter stepped out and vanished. Peter became a paradox because he wasn't supposed to be living in both universes. The universe took its course to take care of him by erasing him. Now how he comes back is mysterious of course. We've to go with that "Love" Theory but it all works out!

Now, in order for Walter to erase observers invasion he's to become a paradox himself and the universe will make it look like he's vanished from the face of the Earth because he's the whole reason why the Observers didn't invade.

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