So, the plausible explanation to who put the wormhole and the tesseract in the place is

Humanity survived through the plan B, that's why they mention it all the time. Then they build the worm hole to save the people of the planet.

But this explanation raises another question and yet another (similar) paradox.

Question -

Why didn't they just simply give us the information from black hole that we need figuring out how to manipulate gravity?

Paradox -

Not to mention that why on Earth would the future descendants (by a margin of more than 1,000,000 years) care to change their timeline in order to save the long dead inhabitants of Earth by eradicating themselves from existence in the process? This is more than a logical question, this is a Mad Scientist Paradox.

References & Sources:

  1. Who exactly constructed the tesseract room in Interstellar?
  2. Interstellar (2014) - Frequently Asked Questions - IMDb,
  3. There is no paradox in Interstellar (on reddit).
  • The way I liked to think of it, the universe is 5-dimensional "structure" (I think this was said in the film), and the events in that structure (our 4d space+time) are embedded in 5d--"solidified" in place. Things play out for us 4d creatures "stepwise", as a linear series of events, from place to place to place, and even though some of those 4d events seem to precede their cause, everything is consistent in the solid, unchanging 5d structure that is the universe.
    – BMF
    Commented Dec 26, 2020 at 21:59

5 Answers 5


Given that the physicist Kip Thorne played a major consulting role on this movie and even co-wrote the original script treatment, I would bet that the theory of time travel being assumed was the Novikov self-consistency principle, in which there is only a single self-consistent timeline, with no ability to "change" the past and no branching of the timelines. Thorne was the physicist who first discovered the theoretical possibility of traversable wormholes in Einstein's theory of general relativity, and the fact that the theory predicts they could be used for backwards time travel under certain conditions. After this discovery, Thorne and colleagues made the case that no matter what initial "boundary conditions" you set up with a time machine, it's always possible to find self-consistent outcomes. For example, in his book Black Holes and Time Warps he discusses the analysis in published papers like this one, which imagines that a billiard ball is sent towards one mouth of the wormhole on a trajectory that, if allowed to continue, will cause it to emerge out of the other mouth in the past, on a collision course with its own earlier self. This would be a potential paradox because if it knocked its earlier self away and prevented it from going into the wormhole, then it should not have emerged out of the other mouth in the past, and thus there would be nothing to deflect its earlier self and its earlier self would go into the wormhole and emerge on a collision course, etc (see the top part of the diagram below, which I found on this page).

The resolution found by Thorne and his colleagues was that the billiard ball might emerge from the other mouth on a slightly altered trajectory, which would still cause it to hit its earlier self but to only deliver a glancing blow that would slightly alter its earlier self's trajectory going into the wormhole rather than knock it away from the wormhole altogether, and that this slightly altered trajectory would be just the right one to cause it to emerge in the past on a trajectory to deliver that same glancing blow--thus there could be a single self-consistent sequence of events (see the middle part of the diagram).

enter image description here

Thorne and his colleagues argued that this is probably how it would always work with time travel scenarios, no matter how convoluted--in fact, they found reason to think that for any given initial trajectory of a billiard ball, there were likely to be an infinite number of different self-consistent continuations, so if time travel were really possible the universe might simply choose one at random (they also analyzed the problem in quantum physics and found that different self-consistent continuations should have different probabilities).

In a universe that respects the Novikov self-consistency principle it is still possible for time travelers to affect the past, perhaps even playing a decisive role in causing certain elements of their own past, even though it's impossible for them to change anything (so they can't eradicate themselves from having existed, no matter what they do). The book Time Machines by Paul Nahin has a section discussing this idea on p. 269 which gives a number of fictional examples, such as the story "The Past Master" by Robert Bloch, in which (spoilers!) a time traveler from the thirtieth century travels back to our own near future to save some artwork from a nuclear war he knows occurred at this time (but does not know the exact cause), and his time machine is mistaken for a Soviet weapon and ends up being the trigger for the nuclear war.

For an example of a time-traveling billiard ball playing a decisive role in causing itself to have gone back in time in the first place, look at the bottom part of the diagram above. There we see another self-consistent billiard ball scenario, one where a billiard ball was originally on a trajectory that wouldn't have caused it to fall into the wormhole at all, but then it gets hit by its future self in such a way as to knock it into the wormhole, becoming that same future self (this scenario was originally mentioned in the paper by Thorne et al. mentioned above, see Fig. 6 on p. 1083, illustrations b and c). This sort of thing is similar to what may have happened in Interstellar--the future beings' trip back to the past (or more precisely, their transmission of gravitational signals back into the past) is the very thing that sets their past selves (i.e. humanity) on a course to become those same future beings and make a trip into the past. We could make this billiard ball scenario even more closely analogous to Interstellar by imagining that the billiard ball's original trajectory was aimed directly at a bomb which would destroy the ball if they collided, so only because its future self appeared from the wormhole and deflected it was it able to avoid destruction, just like humanity only avoided extinction because of the intervention of our own future selves.

A term for this sort of scenario, where a time traveler's actions in the past cause effects that will later ensure that the same time traveler goes back to the past, is a predestination paradox, but it is not a true logical paradox, it's only paradoxical in the sense of being strange and counter-intuitive (i.e. the first definition of 'paradox' here, not the second). This is related to, but somewhat different from, a bootstrap paradox in which there is some object or information that seems to have no creator, like if a time traveler went back with a future edition of the complete works of Shakespeare, and a hack playwright named Shakespeare copied them down in his own hand and released them under his name. This isn't really a logical paradox either, but one might at least doubt that such things would be probable even in a universe with time travel obeying the Novikov principle. (In Black Holes and Time Warps Kip Thorne mentions that for billiard ball/wormhole scenarios where there are multiple self-consistent scenarios following from the same initial conditions, quantum principles can be used to assign different probabilities to different scenarios, but I don't know of any work applying this to cases where there are self-consistent scenarios involving both meaningful and meaningless information loops. It's possible such an analysis might show that bootstrap paradoxes involving meaningful information with no origin are possible but very improbable, in the same way that it's possible but very improbable that a monkey banging away randomly on a keyboard could produce the complete works of Shakespeare). But even if one is concerned about this issue of probability, I think there actually aren't any clear bootstrap paradoxes in Interstellar since the higher-dimensional beings didn't directly give us the correct quantum equations to understand gravity, rather they allowed Cooper and TARS to discover them by falling into the black hole, and then transmit them back in time. Likewise, when Cooper transmitted the coordinates of NASA to his younger self, he had to ask TARS to "feed me the coordinates of NASA in binary", rather than just remembering the coordinates he had received in the past and transmitting them again (which would be a bootstrap paradox akin to the Shakespeare example).

As for why they did it this way rather than simply giving us the information directly, we can only speculate. Maybe they knew that circumstances would tend to thwart attempts to create bootstrap paradoxes, just like how in a Novikov universe they would definitely thwart attempts to create genuine contradictions such as a time traveler trying to assassinate one of their own ancestors before they had children. But another possible answer could be that their minds had grown too different from ours for them to know how to communicate with us directly rather than helping us to figure out how best to communicate with each other (with the movie emphasizing that our ability to communicate, and our intuition for the best person to try to communicate with, is grounded in love), as suggested by these lines from the screenplay:

COOPER: 'They' have access to infinite time, infinite space...but no way to find what they need — but I can find Murph and find a way to tell her — like I found this moment —

TARS: How?

COOPER: Love, Tars. Love — just like Brand said — that's how we find things here.

Based on all this, I don't agree with the answer to the other question, saying that "Humanity survived through the plan B"--the person asking the question (and the person giving that answer) seems to be assuming a framework in which time travel does change the past, so there must have been some "original" unaltered history which gave rise to advanced beings who sent signals back in time, creating a "new" version of history that we saw in the movie. But if you think in these terms, in the original version of history there wouldn't have been a wormhole, since the wormhole itself was constructed by the future descendants of humanity, see this discussion of traversable wormholes by Kip Thorne in Ch. 14 of The Science of Interstellar:

I doubt very much that they can form naturally in the astrophysical universe. My only real hope for forming them is artificially, in the hands of an ultra-advanced civilization. But we are extremely ignorant of how such a civilization could do it ... In Interstellar, however, the wormhole is thought to have been made, held open, and placed near Saturn by a civilization that lives in the bulk, a civilization whose beings have four space dimensions, like the bulk.

So if you assume an "original" timeline with no intervention from our future selves, Plan B couldn't have worked because there are no other habitable worlds in our solar system to settle, and travel to another star system would take many thousands of years with near-future technology. In a single self-consistent history respecting the Novikov self-consistency principle, the timeline we saw onscreen was the original one, so the bulk beings could be the descendants of the very same humans we saw at the end of the movie, perhaps descended from both the people who had escaped Earth under plan A, and the children grown from the embryos Amelia Brand had probably started growing according to plan B.

If this still seems confusing or paradoxical, you might take a look at my answer here which tries to make more sense of where self-consistent causal loops like this "come from", by imagining how we might simulate a universe where time travel works this way on a computer.

  • 1
    There is another way the improbability of information loops could possibly be resolved. An information loop could happen due to alternatives being inconsistent leading to a paradox. For example if without the information loop you would have gone out to search for this information and found it to send it back in time. But once you had send it back in time there would really be no reason to waste time searching for it, because you would already have it.
    – kasperd
    Commented Mar 16, 2016 at 18:44
  • @Hypnosifl: Blurring the lines between Science and Science-Fiction!
    – Möoz
    Commented Sep 13, 2016 at 22:22

They're not "eradicating themselves from existence"; they are ensuring their own existence.
It is a predestination paradox, essentially.

  • 1
    @AnmolSinghJaggi: They didn't change the past. There is one timeline. To quote LOST, "what happened, happened". Commented Jul 19, 2016 at 8:53
  • 3
    @AnmolSinghJaggi: If I'm walking down the street tomorrow and an older-looking me runs up to me and saves me from a rogue lorry, I know that when I grow up at some point I'm going to have to buy a time machine and go back to save myself. :) Commented Jul 19, 2016 at 8:54
  • 1
    @AnmolSinghJaggi: Yes there was. It came back from the future. Commented Jul 19, 2016 at 9:22
  • 1
    I get what you're saying now, but that's only possible if 'the timeline' and all its events (from the beginning of the Universe till the end) were already predetermined when the Universe came into existence. And this would also probably mean that free will doesn't exist. Commented Jul 19, 2016 at 9:29
  • 2
    That also conveniently makes true paradoxes impossible ("huh? how will time stop me from killing my grandfather?" it won't "stop you", you just never did and will never do that thing, period), which is one of the reasons I like this interpretation. Commented Sep 15, 2016 at 0:20

My thought is that they didn't give us the information we needed because they didn't know exactly what we needed or how to communicate it to us. They were sufficiently advanced (perhaps to the point where they don't even have physical bodies any more) that they didn't understand what exactly it was that we needed nor did they know how to give us the information, but they knew we needed some information from the black hole, and knew that Cooper could provide the information (perhaps through historical records)

It'd be like a human seeing flood approaching an ant colony and wanting to save them. The human can see they are struggling with the water, but he has no way to communicate with the ants and tell them that if they just relocated up the nearby hill, they'd be fine - his method of communication is so different from ants that there is no common ground for communication. All the ants know is that they are getting wet, and they need to stay dry, but they are missing the key piece of information that the hill will protect them. However, if the human could lure Cooper the Ant up the hill, he'd see that it's dry up there, and then the human can transport Cooper Ant back down to the colony and let him tell the rest of the ants how to save themselves.

I don't think the future humans are eradicating themselves by saving the humans, instead, I think they are saving themselves. In their timeline, they know that Cooper (from within the black hole) gave the humans the information they needed to survive, and they know that they are descendants of those humans, so they know that they have to save the early humans to ensure their own existence. Regardless of how that particular timeline got started, they know it's in their history so they need to perpetuate it.

Or, maybe they have such mastery over time that it really doesn't matter what happens to the early humans, but they are just being altruistic and helping out their ancestors.


In interstellar( and in reality ) time isn't linear in the way we normally think about it. The future, past, and present all exist and are equally real at the same time. Why not just give us the information from the black hole? The simple answer is that in their past( which would be coopers present ) It didn't happen that way. They had to change our timeline. In the future that's how it happened, therefore they had to do it that way. There is no paradox, just reality.

  • But they would be changing timeline by eradicating themselves from existence in the process, why and how would they do it? Commented Jan 9, 2015 at 7:28
  • 1
    There is no "changing timeline" the timeline is already there. Commented Jan 9, 2015 at 7:30
  • 1
    I think you're suggesting the same basic answer as Lightness Races in Orbit and I suggested, but if so you might want to change the wording on "they had to change our timeline", which is confusing if you mean that they aren't really changing the past, just influencing it.
    – Hypnosifl
    Commented Jan 9, 2015 at 17:58

It's not actually as complex as you may think. For your first question, they know that what they gave was information on a black hole, since they were from the future. Thus, like how Cooper knew to put in the co-ordinates for NASA's base, they knew to only give us a way to communicate. Extensively, had they just given gravity manipulation data, Cooper would have not been able to send back information. The biggest reason is because it was not possible for them to do so. So although they could reach into different moments in time they were 'not bound by anything'. This basically meant that they had no way of seeing progression like how we are bound by time moving forward. That meant they could not 'Find a specific place in time' therefore they could not time travel or send stuff into the past (Such as gravity data). What they did, was include the tesseract with every moment of Murph's bedroom. They had to put every moment in because they could not reach for the right ones.

For your second question: it seems logical to save your past selves from dying so that you can exist. Also, there was no suggestion that they eradicated themselves in doing so. Although they became beings of the higher dimensions, that does not suggest that they changed themselves to be that way for the sake of the movie's events. I reckon it was just evolution.

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