related: Why are there only 2 universes that are visitable?

It seems that there are differences in the universes dating back to the 1930s

Given these differences and the duration that they have existed, I would expect the two to differ much more.

The lack of heavier-than-air flight over there would have significantly altered history—the course, duration and victor of WWII in the very least. This would have global knock-on effects, imagined over 60 years. While I would expect some similarities between the universes, they seem almost identical.

Is there an in-universe(s) explanation for why there is so little deviation between the two universes? Fringe as a show is normally quite good at the science in science fiction. While I appreciate that there are plot and production reasons that the two universes have to be closely mirrored, it would seem that there is a deliberate attempt to have them mostly the same but not identical. I have not as yet seen an in-universe explanation for it. It may not have been explained yet, or I could have missed it.

As a bonus, is there a known diversion event that initially separated the two universes, or have they always existed mirroring each other?

  • If we were to extrapolate your question to its furthest logical degree, we would end up having "over there" be a universe that did not include alternates for any of the primary characters. This would likely invalidate the possibility of the show's premise entirely. (i.e.: Walternate and/or Walternate's Peter never would have been born, therefore Walter would not have reason to cross over, so The Pattern, Massive Dynamic and probably even Fringe Division (either one) would not exist. Also, Fauxlivia and several other alternate characters' lives would be radically different or nonexistent.)
    – Iszi
    Commented Sep 12, 2012 at 14:24
  • Regarding WWII, I (at least, up to S3E10) haven't noticed evidence that it even happened over there. In fact, I remember seeing one homeless guy "over there" with a sign saying he was an "Aruba War" vet.
    – Iszi
    Commented Sep 12, 2012 at 14:31
  • @Iszi This is true. It is obvious that there are plot reasons that they have to be similar, I am just wondering if there is an explanation for it within the show, are the universes linked in some way that doesn't fit with them diverging. (And don't get me started on the kitchen allays existing when Homer gets back from the past in the Simpsons :) ) Commented Sep 12, 2012 at 14:37
  • Strictly speaking, there doesn't need to be. Given a presumption that there are infinite possible alternate universes (even though we're only working with two), it is then possible - if not even inevitable - that there would be a universe such as this one which has diverged in such radical ways, yet still converged to remain so similar to ours. The entire premise of the question is quite bordering on Not Constructive - the only thing (for me) saving it from a close vote is that you've particularly called out for canonical sources. You might want to add just a tiny bit more emphasis on that.
    – Iszi
    Commented Sep 12, 2012 at 14:46
  • Also true, I have changed the question to try to emphasize that point. Commented Sep 12, 2012 at 14:54

4 Answers 4


I think this is explained by Walter's initial alternate-universe infodump from "The Road Not Taken":

WALTER: Each choice... leads to a new path. To go to work. To stay home. And each choice we take creates a new reality. Do -- do you understand?

OLIVIA: Yes. But what does it have to do with deja vu?

WALTER: Deja vu is--is--is simply a - a momentary glimpse to the other side. Almost everyone experiences it. We feel that we've been somewhere before because actually we have - in another reality. It's another path. The road not taken.

So it seems that alternate universes in Fringe don't actually evolve independently of each other; people from one universe get flashes of memory from their counterparts in other universes. It's not too unreasonable to believe that these flashes cause them to behave similarly to each other (e.g., replicating the same relationships and therefore having the same children...) even given somewhat divergent circumstances.

As Peter says in "White Tulip," "deja vu is fate's way of telling you that you're exactly where you're supposed to be." So presumably all the other yous are there as well...


Let's presume a couple things, one which is not quite evidenced in the show (but a fairly logical presumption nonetheless) and one which is foundational to it:

  • The prime universe in Fringe is, more or less, our universe. In our universe, it's been widely speculated that there are an infinite number of parallel universes in which history has unfolded in ways which may differ only slightly or very drastically.
  • Walter has proven that there is at least one parallel universe, both by observing and visiting that universe. Walter's experiments have caused our two universes to bond in certain ways which make it easier for us to travel between and interact with the other universe than would otherwise be natural.

Given that there is, for certain, one parallel universe it is then much more likely that the "infinite universes" theory is also true. The universe where Walternate, Fauxlivia, and friends live just happens to be the first we've discovered. Since it's now also the easiest to travel to and interact with, it also just happens to be the only one we really care to acknowledge exists at this time. It doesn't exclude the "infinite universes" theory - it just means we're currently ignorant to the existence of the others.

Presuming a literally infinite number of alternate universes, the probability of there being a universe in which we see so many significant changes alongside so many significant similarities is just as much as the probability of there being one in which we see the "Butterfly Effect" fully manifested like we'd expect. In fact, by the very nature of the multiverse stretching into infinity, the existense of both these universes alongside ours isn't just probable - it's inevitable.

For example, if our first discovery of an alternate universe were truly by random chance (as, realistically, it probably would be) then it's much more likely that the first universe we ran into would be one in which Earth did not exist at all. Perhaps even the entire solar system, or the Milky Way galaxy, might not even be there. Or we could discover one of a number of universes in which a scientific experiment gone wrong caused the sun to age and cool prematurely, putting the Earth into another Ice Age. Another possibility would be that the first universe we discover is one in which the dinosaurs were never wiped out - instead of humans being the dominant species, the Earth is crawling with these huge, terrifying lizards who may or may not by this time have evolved to have intelligence and technology.

Given all the possibilities, it's really very unlikely that the universe we would first discover would be that one among infinity which is so unlike ours and yet still so similar. But, if it wasn't, then we wouldn't have a show. Or, at least, that show probably wouldn't be Fringe - it'd be more like Sliders.

This may or may not ever be covered in canon, but it's the most logical explanation I've been able to come up with.

  • Actually, using Sliders as a basis, it makes it more likely that the first universe we find would be very similar to ours. Sliders had a spectrum of universes, some closer and some farther. The coordinates of the nearby ones are more similar to each other than not - making them easier to slide into. In Fringe, the two universes coooould be nearby in a similar way - which is why Walter's window just happened to be picking up photons from only that universe, it's the one closest to ours...
    – Izkata
    Commented Sep 14, 2012 at 14:08
  • @Izkata Given infinite alternates though, it's much more likely that the one closest to ours is one in which the only difference is what Walter had for breakfast that day - not a universe that's been diverged for nearly two centuries. My primary point is that really, given infinite possibilities, it's inevitable that this universe does exist while at the same time the full-on "Butterfly Effect" universe the asker expects also exists somewhere out there. The show just wouldn't be the same (perhaps not even worthwhile as a show) if we went to the latter instead.
    – Iszi
    Commented Sep 14, 2012 at 14:26
  • I think this is a perfect answer if you also factor in the psychic factor that play a big role in the Fringe Universe (whose physical laws are not necessarily the same as ours). It is reasonable to assume that the first universe Walter finds would be very similar to his.
    – timur
    Commented Jun 10, 2013 at 17:30

Similar to how both universes must remain balanced - a theme that was explored fairly in-depth during Season 3 - there's evidence that the timeline is, to a certain extent, elastic. But only as long as the universe is not interacted with by an outside force - that throws the chain of events out of whack and causes the large divergences predicted by the Butterfly Effect.

Here are a couple known points where our universe was influenced by outside events:

  • When Walter first made the window to see Over There
  • When Walter took Peter to our side
  • When August saved the girl

Likewise for Over There:

  • When September distracted Walternate
  • When Olivia told Walternate about the "other universe"
  • William Bell

In 2x16, Peter, we see September talk to other Observers about the mistake he made, and how he has to correct it. Likewise, August was told that his mistake would be corrected, but he figured out how to avoid that fate.

This suggests that, at least from the point of view of the Observers, both universes have a predefined path. Unless a mistake or intentional change is made, the small differences caused by the presence of the Observers is negligible, and won't cause the timeline to excessively diverge.

On the other hand, any time a universe is influenced by an outside force, unless that outside force takes extra steps to keep the universe on-course like the Observers, that's when things start to spiral out of control.

We were given an example directly by an Observer in 3x10, The Firefly what happens when an outside force influences a universe. In September's own words to Walter, after the example: "You and I have interfered with the natural course of events. We have upset the balance in ways I could not have predicted."

Up until then, the differences between the two universes did not spiral out of control (Even DC's superheroes are largely the same; different color scheme, and Supergirl survived Crisis on Infinite Earths instead of Superman, but all the same heroes exist). Given the same people in similar situations, they will tend to take similar courses of action.

The times they did not, there are some pretty large changes. For example, here's extracts of two lists of some fairly large differences between the two universes, either with regards to the world or the main characters:

  • William Bell died young and never met Walternate.
    • Walternate had a lab anyway, and went on to found Bishop Dynamic.
  • There's no indication that Nina Sharp ever existed Over There.
    • Likewise with David Robert Jones.
    • I'm wrong about Nina, see Season 4. So far, there's still no indication about Jones.
  • Lincoln Lee had a very different life.
    • As did Astrid.
  • The Hindenburg, as mentioned in the question.
  • Andrew Jackson either didn't exist, or was never president.
  • The Challenger disaster didn't happen - those 7 crew are presumably still alive over there.
  • US states include: North Texas, South Texas, Midland, and Dakota (One state, not North and South), among other changes
  • Fauxlivia was with Frank Stanton, not John Scott like our Olivia. We don't know if either one exists in the other universe.
  • The Hotel Attraction was built Over There.
  • Casablanca, The Maltese Falcon, and Back to the Future all were made, but with different stars.

So there are some pretty drastic differences. There is no outside force keeping the two universes on a similar course of events; it's just coincidence due to most people making similar choices between the two universes - Andrew Jackson wasn't president, but someone else was. Those three movies were sill made, but with different actors. Some other hotel was in use instead of the Hotel Attraction. Zeppelins were used instead of Airplanes, which were never invented Over There. So on and so forth...

The only times (that I can think of) where a universe has been pushed into a specific course of events has been by an Observer that was fixing a mistake they made. Otherwise, similar courses of events is the expected norm.

  • The question here isn't saying there aren't any differences, or that there aren't a lot of differences. It's saying there should be more, and much more dramatic, differences because of the presumed Butterfly Effect which has had several decades to develop. (Link points to TVTropes - you've been warned.) Given this presumption, the asker wants to know why there aren't more and more pronounced differences.
    – Iszi
    Commented Sep 13, 2012 at 1:45
  • 2
    @Iszi The universes diverged at least as far back as 1829 (the start of Andrew Jacksons's presidency), but There's also suggestions that two universes tend to circle around each other in terms of events. What I'm pointing out is that the Butterfly Effect has caused massive changes in the structure of that world (North Texas/etc, 3 equally-important political parties, and so on), but when one person can stand in for another (the movies, Lincoln for Walter), events take a fairly similar course of action. The two universes only look extra similar because similarities are easier to spot...
    – Izkata
    Commented Sep 13, 2012 at 2:04
  • ...and, of course, we do need to recognize the main characters. But several of them were given radically different backstories to highlight that they are different. I can try and expand on this in the answer if that'll help.
    – Izkata
    Commented Sep 13, 2012 at 2:06
  • 1
    I think the asker here is recognizing that there must be something that's causing the two universes to converge towards the similarity they maintain - "circle around each other" as you say - but he's looking for a reason. Why, if major historical events turned out so differently, have individuals from our universe still been born from the same lineage and followed (roughly) the same path in life? Aside from that, why are the universes still maintaining such unexpected similarity in so many other ways where one would naturally anticipate they would be much more different?
    – Iszi
    Commented Sep 13, 2012 at 3:09
  • In a more likely sequence of events, following a divergence that's begun at least 183 years ago and caused such radical differences as we have seen, the individuals in our universe (and a good portion of their ancestry) would not have even been born in the other. Even if they were, it's still very unlikely that they would more or less have the same jobs or educational background in the other universe. Entire cities should be drastically altered, not just a few buildings. With as many major differences as there are, the similarities are really what don't belong. Is there a canonical reason?
    – Iszi
    Commented Sep 13, 2012 at 3:16

WALTER: One minute will explain. (rolls out a chalkboard) Most of us experience life as a - a linear progression just like this. (draws a horizontal line) But this is an illusion because every day, life presents us with an array of choices. As a result, life should look more like this. (draws diagonal branches from the first line) And each choice... leads to a new path. To go to work. To stay home. And each choice we take creates a new reality. Do -- do you understand?

OLIVIA: Yes. But what does it have to do with deja vu?

WALTER: Deja vu is--is--is simply a - a momentary glimpse to the other side. Almost everyone experiences it. We feel that we've been somewhere before because actually we have - in another reality. It's another path. The road not taken.

Fringe, S1E19, "The Road Not Taken"

If each choice creates a new reality, and each choice in that reality creates another new reality, there are an infinite number of alternate realities.

Of all those infinite realities, Walter just happened to tune in to this one, where the events have played out as they have. Over Here may look just as improbable seen from Over There.

It's important to note that after having done so, the splitting off of realities didn't stop. There must be another group of realities where he didn't like the reality he tuned into and kept on searching. And yet another group where he didn't choose to interfere. And another where they where never joined. And... And...

You see, infinity is really big.

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