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     Is Nolan a climate change skeptic? 
Doctor “Mann”, played by a heavy environmentalist, makes up a complete story that a planet is far warmer than reality...
  • (1)The beliefs of individual characters are not a representation of the author's view on said subject. (2) Mann fabricates data because he's driven insane by isolation. How is that even comparable to what climate change denialists believe the scientists to be doing? That they both tamper with data? It's like comparing surgeons to butchers because they both use knives on living flesh.

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    Why not stay on Earth? 
Flying a tiny portion of Earth’s population off the planet is extremely implausible. Ok, the movie attacks the angle of implausibility head on. But, whatever this blight is, if they can make a space ark without the blight— a sealed environment— why can’t they far easier do that on Earth? Forgetting the magic anti-gravity thing, the energy needed to evacuate just one person out of Earth’s gravity well is several orders of magnitude beyond that needed to build and maintain a sealed environment on Earth.

    Why is adult Murph so angry at Cooper? 
I can see that when the elder Professor Brand confesses his sins to Murph that she flips out and has a major crisis of faith. But a lot of time passes before she sends her angst message to the Endurance, and more before she shows up at Tom’s farm. Yet, she’s still furious. But this seems so insanely self-indulgent.

She’s a brilliant lifetime trained scientist. She has to know that her father was not a rocket scientist, and probably didn’t know a fraction of the physics. And she bitterly attacks Cooper for abandoning her on Earth— she must understand that Cooper flew off on a mission that was darn near a 99.9% a suicide mission. She makes it sound like Cooper was flying off to Rigel to hang out with some green slave women.

    Wormhole Placement 

  • How did the wormhole get there? If future humans put it there, where did their ancestors come from?
    • A Stable Time Loop.
    • Are you implying future humans put it there? What is the evidence for that?
      • The wormhole was artificially produced, this is actually mentioned in the movie. And Cooper theorizes that the 5th dimensional beings helping us are actually are our future selves.
    • Is a stable time loop logically coherent? Can my Friday self save my Wednesday self from being killed on Thursday? Where did my Friday self come from?
    • Your Friday self would be the future of your Wednesday self - that's how those loops work. Unless they've Tricked Out Time, the effect is part of the cause.

    Fifth-Dimensional Limits 
  • What are the limits, if any, of the beings that made the wormhole and/or the tesseract? Why don't they (or, if there are multiple they's, any of the they's) communicate the necessary info to make plan A work / overcome gravity? Or which planet(s) are optimal? Or the cure for blight? Or any messages whatsoever?
    • Because the only thing that can move back and forth in time are gravitational waves, and the beings responsible seem to be very limited in their interactions with the four dimensional universe because of this. They needed Cooper as an intermediary to get data through where it was needed.
    • Because otherwise we wouldn't have a movie. The gravity-based communication of the movie is plenty to draw the attention of primitive humans, so by all rights they should be uplifting humanity from the moment they invent the concept of abstract language, avoiding millennia of suffering. The exits of wormholes may occupy any point in spacetime, even the past, and the wormhole in the movie was created in the past, from the perspective of future humanity, so they should just be able to place wormhole exits at the start of the universe and colonise everything before the first fish ever would have crawled on land on since-rewritten-earth.
    • The Stable Time Loop prevents this from happening, as does the fact that the beings don't have a perfect control over to which time period they send their anomalies. They had to put the wormhole up 50 years before it was needed because they couldn't figure out the exact moment, which is probably also why they couldn't relay any messages in their own right, relying on a human intermediary, instead.
    • The wormhole was sent back 50 years "early" because humanity needed to know interstellar travel was possible and to prepare to make the journey. If a wormhole opened right now I would expect we wouldn't be able to go through it until we made significant technological advances and had the ability to pool our resources.
    • The implication I got was that they simply had evolved or developed so far that they couldn't conceive of a way to communicate. The farthest back we could go in the evolution of the English language is about the 15th Century and still be able to understand the language. And we're talking about a civilization that is on an entirely different plane of existence.
    • Improvement in a civilization's development would also mean an improvement in ability to understand more primitive versions of self. Retrocompatibility is largely a matter of brute force: a sufficiently powerful modern computer may emulate any digital machine to ever exist, and this trend is likely to be preserved in the future. If English vanished from spoken language altogether, we could still relearn it about as easily as any other foreign language from all the information we have on it. It's different from something like Latin where the info just isn't around anymore to recreate it completely because the old records were imperfect. Ironically, it makes more sense at the start where they assume it's aliens who'd always have been 5th dimensional and not comprehend our 4th dimensional universe, but future humans makes it harder to swallow.
    • Ultimately, any civilization that mastered time travel can always ask for help from future versions of self, including the one that can take into account any time paradoxes. This is, of course, assuming that five-dimensional beings have their own equivalent of time in which they advance. They likely do if they exist at all: being in every state at once is not very compatible with any information processing and other abilities of a sentient creature.
    • We can only assume that They are not omnipotent, and They're subject to various rules and restrictions that our puny little modern-day brains couldn't possibly comprehend. I figured that They were just doing the best They could, under the circumstances.
    • This is nor even similar to travel back in time to Speak with a 15th century English speaker, is like trying to communicate with ants. Yes, is probably possible, but it will be very difficult. Or even a less radical example, is like if we travel back in time to tell something to our hominid ancesters like a homo erectus, it won't be easy.
    • This is actually a point Cooper makes, they are NOT changing the past, the events in the movie are how things were supposed to happen. The 5th dimensional humans most likely would want to make things much easier for their past selves, but they just can't or the stable time loop would not work.

    Saving Cooper 

  • Did the beings save Cooper from the black hole? Does this interaction contradict their "limits"?
    • They shoved Cooper back out through the wormhole when his job was done. Presumably it was thanks to Cooper's actions that they knew the exact right moment to have him rescued. Since he did not travel to the past, it doesn't contradict the earlier limitations on time travel.
    • Passing the event horizon of a black hole equals traveling infinitely far into the future. Or, allowing for Hawking radiation, to the moment in time the black hole decays naturally, many billions of years in the future. However, there is no physical reason why wormholes would transport only across space, and not across time, so since the wormhole was created by those beings, it does not contradict their limits. Rather, they just don't make effective use of their limits.
    • The movie physics In real world physics, yes, but in the film's physics the black hole instead acts as a gateway into the fifth dimension and exists outside time, altogether.

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    Traveling to and from the tesseract 

  • How did Cooper go from eject to the tesseract? From the tesseract to Saturn?
    • As mentioned above, through the original wormhole.

    Death 

  • What if Cooper had died at any point before ejecting? How would the beings (via Cooper or anyone else) have communicated with the chosen one Murph?
    • A Stable Time Loop ensured that wouldn't happen.
    • This is also limited thinking. To the fifth-dimensional beings, everything that has happened and will happen to ordinary humans is happening right now. Possibly, the "time" they themselves exist in is a separate dimension altogether, because otherwise, if there is no past or future, just the present, they wouldn't be able to think. However, it doesn't mean their 6th dimension "time" is similar enough our 4th dimension to be compatible with our frames of reference; it may not be built upon a linear progression.

    Passage of Time 
  • How much Earth time passed from Cooper's eject-tesseract-Saturn? Why can't the beings spit Coop out earlier?
    • Because due to time dilation Cooper was already decades into the future from the point of his departure, and it is not possible for physical matter to be sent back in time under the rules established in the film's physics.
    • The film's physics attempt to emulate real physics. In real physics, time dilation goes to infinity as you near the event horizon of a black hole. The "hour on the planet is eight years on earth" thing would be infinitely strong for Cooper as he crossed the event horizon, so if travel back in time wasn't possible, he would have to be sent back out only when the black hole naturally decayed, at least ten billion years in the future.
    • As said above, the film's physics don't match the real world physics perfectly. It envisions the black hole as a portal to the fifth dimension, to a space outside time, and Cooper doesn't physically move either back or forward in time upon reaching it, but stays at the exact moment that he entered the event horizon in the first place.
    • I don't think it's fair to say that black holes being portals to the fifth dimension is an inaccuracy. We simply don't, and can't, know what's on the other side of the singularity. It's like the afterlife: speculating about it isn't unscientific because science will never be able to answer it either way.
    • The main problem with this is that you're not supposed to ever cross said horizon: time close enough to it just keeps slowing the closer you get to it, so that you won't be able to reach this horizon before the black hole decays via Hawking radiation. Therefore, the main issue of the movie can be summarized as inconsistency in portrayal of black hole: its time dilation effects are acknowledged at a planetary orbit's distance and ignored up close.
    • The 'black hole' is this movie can act inconstantly with RL physics because its not a real 'black hole'. Aliens/Future People that can time travel and exists in a higher dimension can probably create a special machine, dress it up as a black hole to get the humans' attention, then go to town in its inner workings. The movie mentions this particular back hole was very old and 'gentle', and real physics tells us that this conditions in Miller's planet are not impossible, but extremely rare. For all we know, there are real black holes out there in the movie that do obey physics better, its just that this one, Gargantua, was artificial or otherwise tampered with. It did turn into a out-worldly library, after all.
    • Because if he had been 'spit out' sooner, he would have died, there would have been no one near to rescue him. It would have taken time for Plan A to be fully enacted, for the planet to be evacuated, and for them to reach Saturn. Years at least. If Cooper had been spit out at the time he had entered, he would have floated in space with no additional oxygen....and no rescue. So....that would have been bad.

    Amelia alone 

  • Given the time They chose to spit Cooper out near Saturn, given how much Earth time that has passed (even accounting for relativistic time slowing), and given the success of plan A, why is Amelia by herself at the end?
    • Because Earth's fleet is only preparing for the jump through the wormhole. Presumably they are in the process of doing further experiments and trying to contact Amelia and Cooper with drones before going through. As for how much time has passed, they explicitly mention that Cooper is now chronologically 124 years old.
    • Note that Amelia had to go very close to a black hole before passing on to Edmund's world, so time dilation meant that she's just barely getting the new colony set up at the end of the movie. She's alone because she only recently got to Edmund's world.

    Murph's room 

  • Why was Murph's room (and only Murph's room*) in the tesseract? (*also see Amelia handshake question below)
    • This goes into wonky New Age-physics. Apparently the Power of Love lets one navigate in the fifth dimension, which is why the beings needed Cooper in the first place to find the exact right moments in our four dimensional universe to send the message through to Murphy. TARS does mention, however, that what Cooper sees is just an approximation of the Alien Geometries impossible for human to perceive properly, and that the beings arranged it so for his comfort. This could be salvaged, somewhat, if there was a Minovsky Physics explanation about how the bond between people is actually quantum entanglement that transcends time and space.
    • Okay, I think people are mistaking how dimensions work. We live in a three dimensional universe, along with the characters. Okay, live is the wrong word, but without getting too heady or existential, we experience only three dimensions of an 11 (depending on who you talk to) universe. The fourth dimension is time, but to experience time in the truly fourth dimension, you'll have to be able to move both back and forth in time, much like how we can move back and forth along the X, Y, or Z axis in our world. The fifth dimension would be if we took a "left" or "right" off of the time axis, what would that be? That's where the fifth dimension "humans" are. Cooper, gets to experience the totality of what it's like to be a fourth dimensional being while in the tesseract. He can go to any point in time, forward and backward, at his pleasure. The fifth dimensional beings get to experience all the probabilities and permutations that can and will happen. The fifth dimensional beings, having experienced the Earth that was, tried to rectify one of the time lines that's at their finger tips. Murph's room was chosen because Murph was the one to move humanity beyond. In the fifth dimensional being's point of view, in all time lines, Murph is the key. Cooper was the messenger for the information to pass along.
    • Not necessarily. Alternately, they took Cooper and worked backwards trying to find an emotionally significant bond in his memories, so Murphy was predestined strictly because of a Stable Time Loop.
    • — The answer above is tremendously helpful for understanding the movie. Bless you. Related to the first question of the page, my main headscratcher is: what percentage of viewers have ANY knowledge or understanding of "how [five] dimensions work"? One? Five? Ten, at most? If a movie's ending is a headscratcher to many without reading more (this is the current evidence based on online discussions and videos of post-movie interviews), then doesn't that limit its effectiveness and accessibility? This gets at the philosophy of art and how much understanding the literal story matters.
    • Possibly, but this then raises the related question of whether art needs to be purely or entirely accessible in order to be effective. Shouldn't art raise questions in the viewer's mind as well as merely answering them?
    • The big meta I see here is using the movie as a medium of science communication. A lot of little kids (and quite a few adults) wanted to know what a fractal was after it appeared in Frozen. Likewise, a lot of people will want to investigate dimensions and black holes after watching the awesomeness of Interstellar. If this ever helps to prevent the interest in space exploration from fading like it did in the movie universe, then it arguably has helped to fulfill its most important message by itself.
    • The easiest example is that the 5-dimensional beings knew the specific 3-dimensional spatial coordinates to transmit the information (Murph's room), but not the time dimension. Since a human mind trying to understand all 5 dimensions simultaneously would Go Mad from the Revelation, the Tesseract effectively re-maps both time and the 5th dimension to the existing 3 spatial dimensions we know. It would be like taking a two-dimensional square and flipping it on it's side. We would see it as simply moving in a different direction, but it would be experiencing new places it would otherwise be completely unable to reach.
    • Mann goes on to talk about the last thing you see before you die is your children. This causes you to make that one last push for survival so you survive for them. When Cooper dropped off the main ship to enter the singularity, he was basically going to die, at least for all he knew. So, his survival instincts would kick in. Since modern science doesn't know anything about what happens inside a singularity, it could mean anything. One might argue that what you see is what you observe. Since his child was in his mind, he would see his child. It's the physics, of quantum mechanics. It's what Cooper observed. The robot would actually be able to see data for what is there. Being not a sentient being but a computer, he'd only collect data. He'd observe it and then inform Cooper. There is a big deal about data and black holes. Amelia did go on about how love is something and we shouldn't stick to just the facts. She may be in the wrong because she did so outside of logic. She was being intellectually dishonest, but because of the nature of the black hole, she was actually correct. Cooper saw it because he needed to see it. The ability for Cooper to affect his daughter with gravity is again, due to the nature of the information in the black hole. At this point, it's a little weak to believe that the unknown physics of the tesseract can cause gravity to be sent to the exact right place and time. It's also a little weak to believe that it has to be that bookshelf. There really isn't a good reason to explain this.

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    Mann's reasons 

  • Was Mann following orders to ensure plan B's success? Or just going nuts? Or something else?
    • He was simply insane from isolation, and trying to justify his self-serving actions the best he could. He would have probably still worked for the plan B, if given the chance, seeing that it was his only chance at long term survival.
    • Yep, he's pretty much just insane. He could have come clean and told them that he had faked his data as soon as they woke him up. Sure they would have been angry, but it's not like they would have left someone with useful skills behind when they'd already lost a man. Instead Mann decides to kill everyone and steal their ship. Then he pays no attention to all the alarms and Brand telling him he's about to kill himself and probably destroy the Endurance, which would obviously scuttle plan B. Mann was simply no longer playing with a full deck.
    • Also, Mann's got an ego. Pretty much everything we hear before we meet him is about how Mann is, well, the man, he's the top guy, the leader, the one everyone expects to succeed in the mission. And notice how much of Mann's dialogue basically revolves around saving humanity. Even his last words are the beginning of some grandiose lecture about how he's doing what he's doing for all of humanity. On some level, Mann feels entitled to be the hero, the one who saves the human race, so when he discovered that his world was basically uninhabitable, he didn't handle it well.

    Communication choices 

  • Given Cooper had time to Morse tons of data, instead of sending "stay" to little Murph, why not Morse "dad" or "Cooper" or "I am dad" or "I am Cooper" or page after page of some unique info he could recognize—day after day—to convince him it's him and then Morse, "dude, stay at home and raise your kids up right, the 5th dimensional deus ex machinas (and/or others) have got this. Trust me, brah. Get a telescope and look around Saturn. See that weird thing? OK, this is your future self from a crazy tesseract and They got this—no matter what I/you do for or against it." Or how about just not Morsing the NASA coordinates?
    • Again, Stable Time Loop. As soon as Cooper came to his senses and realised what his mission was, he completed it to the letter. It was, after all, the only way to complete the time loop and ensure humanity's survival. Considering the amount of data that had to go through, confusing it with additional, personal messages would have probably only made things harder for Murphy.
    • He also wasn't thinking logically. To him, he was seeing past events unfold in front of him and was only thinking that he has to change it so he can see his kids again and not break his daughter's heart. It wasn't until he calmed down and TARS started talking to him over his radio that he started really connecting the dots and realized what he was there to do.

    Seeing the ship 

  • How did Cooper see Ameila's ship (and not just Murph's room) while in the tesseract? How did Cooper "shake hands" with Amelia? Can Cooper see and/or interact with anything anywhere anytime?
    • Cooper was ejected from the tesseract and on his way back to Sol via the wormhole; presumably, the nature of the wormhole's four-dimensional structure put him near the Endurance - if you're using the same road, you'll pass anyone heading the opposite direction even if you're in another lane.

    Knowing about Murph 

  • How did They know about Murph?
    • "They," being in the fifth dimension with time as the fourth, were able to perceive all possible permutations of time, much in the same way that you can perceive all parts of a two-dimensional sheet of paper from the third dimension. In all timelines that led to Their existence, a little girl named "Murph" was the one to crack the equation that led to the development of gravitational manipulation and, subsequently, to humanity's survival and ascendance.
    • Also, whatever Their equivalent of history textbooks are. She was pretty much the saviour of humanity, after all; naming a space station after her was probably the least a very grateful human race did over the centuries that followed. You might as well ask about how we know all about Isaac Newton or Albert Einstein — because they had significant impact on scientific theory and the development of our species, so we keep writing about and remembering them.
    • Chicken and egg issue. There is no beginning or end to a Stable Time Loop. They could've set up the wormhole first and deduce Murph from Cooper's memories. If time tends to rubber-band into place like it usually does in fiction, it was completely guaranteed that once they allowed things to happen by setting up a wormhole, they would proceed in a way that allowed them to exist in the first place.

    Why create the wormhole 
  • Why do They create a wormhole (or help us at all)?
    • "They" are humans who've transcended our dimension. Saving present-day humanity is part of a Stable Time Loop. Saving us is saving themselves, retroactively.
    • Maybe. There's no proof of that. Also, if they were future humans, wouldn't they know from historical data exactly when and where to intervene? I guess if history says it happened the way it did, though, they would have had to do it that way.
    • They would only be able to know the exact place and time to intervene if they still bother tracking things like exact dates and places. They've transcended time and space, and our understanding of dates, times, and places may be completely incomprehensible to them. Using "Love" as their guide may be the only way they can hit an approximate place and time.
    • Who says they don't know when and where to intervene? Everything ended up working out almost perfectly as a result of their intervention, after all. And although it might not seem like it at first glance, if you look carefully everything that happened appears to have happened at just the right time for it for it to happen.
  • Why can't any relevant information about gravity be obtained from the study of the wormhole rather than the black hole? A wormhole is by definition the application of gravitation's time-space bending effects to the extreme. Any gravitic drive humanity may end up creating is nothing but replicating a weaker version of this very effect.
    • Moreover, it's also a time machine. It's a connection between two arbitrary points in space -and- time. Any instantaneous travel of distance via wormhole is also time travel, due to relativity.

    How create the wormhole 

  • How did They create a wormhole?
    • Sufficiently Advanced Humanity
    • According to some wormhole theories, including those of Kip Thorne (the film's theoretical physicist), to keep a wormhole open long enough for an object such as a spaceship to travel through requires the harnessing of anti-gravity. Anti-gravity is related to anti-matter and anti-energy (presumably). These, as of yet, have only been shown to exist mathematically. We have observed their effects and know there has to be something there, but we have no actual idea what most of their properties are. There is some speculation anti-matter may exist in the fourth, fifth, sixth dimensions etc that we can't perceive. So perhaps the fifth-dimensional beings from the film can perceive anti-matter, anti-gravity, what have you. It wouldn't be a huge leap (they have evolved into fifth-dimensional beings after all) that they would be able to harness this anti-gravity somehow and create the wormhole.

    Helping Plan A 

  • Why do They help us with plan A?
    • Plan A succeeding is a side effect of humanity discovering the secret behind gravitational manipulation, which is necessary for 5th-dimensional humanity to exist in the Stable Time Loop. It's not so much that They help with Plan A, it's just that They help us to survive, and in doing so enable us to fulfill Plan A.
    • It's possible that the Plan B did work in the first timeline (as we know, Edmunds planet was habitable) and that would explain the existence of the "aliens" and why they are from another Galaxy. The incredibly advance fith-dimensional beings are the future evolution of the Edmunds colony, once they reach that state they help humanity achieve Plan A out of altruism and/or because is logic to wish for having more super-evolved humans in the future.
    • There is no "first timeline", as Cooper says, they are not changing the past. Odds are the first step into becoming fifth dimensional beings was giving themselves a way to manipulate gravity in the past.

     And Speaking of Plan A... 

  • Professor Brand knew all along that Plan A was impossible without data collected from the inside of a black hole. When our intrepid astronaut heroes learn this terrible truth, it only takes them a few minutes to concoct a plan to collect such data. Surely, the guys back at NASA H.Q. must have thought of the same plan themselves, decades earlier! Why didn't they send a mission to collect this data, instead of just sending a mission to check up on the earlier Lazarus launches?
    • They concocted a plan to jump inside a black hole, but they had absolutely no way of knowing if they could get the data out. And they couldn't, not using their own equipment. They needed a Stable Time Loop giving them access to advanced gravitic manipulation techniques to pull that off, which no one could have seen coming. Coop and TARS decided to fall into the black hole because they had no other choice to get the Endurance out of the gravity well, not because they actually thought they'd survive the experience or be able to tell anyone if they did.
    • Correct. Prof. Brand believes it is impossible to collect the necessary data for the gravity equation from the inside of a black hole. They mention that earlier (unmanned) probes had been sent into black holes without result. So he concocts a plan that might work to save humanity - Plan B - and gets his plan going, including recruiting astronauts and securing funding from an anti-intellectualist government, by using the "we'll save the people living on Earth now" Plan A cover story while in reality counting on Plan B.
    • Prof. Brand did not know that it might be possible to send data out of a black hole because he never had an opportunity to study one. Romilly spends years collecting closeup data from Gargantua and analyzing it, which allows him to come up with an idea how TARS might possibly be able to do it. As they believe they are going to proceed with Plan B on Mann's Planet anyway, there is no reason not to give it a try, even if the odds for success are bad. In the end TARS never has to attempt it as Cooper does it instead via the tasseract.
    • Brand thought it was impossible to get the data he needed for the gravity equation. Romilly finds a way that might possibly work. Brand should have realized that someone like Romily might be able to do such a thing, if he had sufficient time to study a black hole. Even if Brand felt that he had to lie to everyone in order to ensure Plan B would happen, he should have changed his approach as soon as the Endurance had left the galaxy. He should've said "Hey everyone, this gravity equation would be a lot easier to solve if I had some black hole data", and then he could've gathered the brightest minds in NASA to figure out how to get that data (e.g. by sending another ship to Gargantua with that specific purpose). In 23 years, they might have come up with something! Instead he wastes everyone's time by deliberately pursuing a dead end. Deception may have been necessary in order to get Cooper to comply, but after he left there was no reason to keep up the facade anymore.
    • It was necessary to keep everyone else's spirits up and working. Intellectually, both plans involve saving the human race — but emotionally, one plan involves letting every single person on the planet except for a handful of people who manage to get off die slowly. That's not exactly good for morale.
    • Brand may have felt that even though Plan A was impossible with information currently available, pursuing it along with Plan B was still the responsible thing to do. He may have considered that once it was in motion, unforeseeable lessons might fill the knowledge gap for it to work, just as it did work out.
    • This ties into the film's theme of hope vs. despair. Based on the current information he has, he no longer has hope that it's possible to save any of the human population currently on the planet. He doesn't seriously pursue the option that might enable this because he doesn't believe it's possible; essentially, on this matter he's given in to despair.

    Time Loop 

  • Given They and the Stable Time Loop, was the human race ever in danger of extinction during this movie? What role, if any, did "current day" 3d humans play in saving humanity (3d and/or 5d versions)?
    • Technically, no - given that it's a ''Stable'' Time Loop, Their existence precludes the possibility of failure. However, They are limited in their influence in lower dimensions, specifically being unable to pinpoint the time and method used to get the information to Murph that'd save humanity, and needed to manipulate a human intermediary (Cooper) to do it. Since it's a time loop, every party is equally responsible for saving "metahumanity" in a paradoxical form - if Cooper hadn't done what he did, 5D humanity wouldn't exist; if They didn't exist, Cooper wouldn't have done what he did. If anything, Murph is the most important character, since everything hinged on her being able to figure out the gravitational equation, and both Cooper and Their actions only served to get her what she needed to do it.
    • an interesting possibility if there is a multiverse (which the movie doesn't explicitly contradict) - the "5th" dimension could be hopping 'across' timelines. It's like building a bridge, for someone beneath it and unable to look left and right, only straight up, it would be a total mystery as to how a person is floating on a platform directly above. For a 5th dimensional being, able to move 'laterally' across time, they could literally be "building a bridge" via saving humanity to be able to exist within our timeline/dimension. If we didn't survive... perhaps they would just build the bridge elsewhere.

    Artificial Gravity 

  • If they've solved the problem of gravity, why do they still need rotating cylinders? Shouldn't an understanding of gravity sufficient to levitate earth's population off the planet also be sufficient to implement some sort of Artificial Gravity?
    • Centrifugal acceleration might be more efficient, or manipulation of gravity on such a precise scale might not be possible or practical for their technology level.
    • They didn't solve the "problem of gravity" until Jessica Chastain!Murph recieved the data TARS and Cooper sent to her. In the Plan A arcs they do make of use Murph's Artificial Gravity. Until that point they had to rely on 2001 style rotation.
    • Maybe they did. We never see the space stations from the outside to even say for sure that they're rotating. And playing baseball in a rotating cylinder of that size would be challenging if not impossible with the Coriolis effects. The ball that gets hit straight up seems to follow a totally straight trajectory when in reality it should curve if they're on a rotating cylinder.

    New World 

  • So the ending is that humanity is moving to a new planet... that's very close to a black hole right? Is this really a safe place to live? (Apparently humanity managed to live on long enough to develop 5D technology, but still)
    • Of the three worlds, Miller's is closest to the black hole, Mann's is a bit farther out, and Edmunds' is well outside its radius. In the end, they're planning to settle on Edmunds'. It's not the safest place in the universe, but it's better than Earth.
    • With the gravity equation solved, humanity could use a planet around the black whole as a stepping stone to other planets. I feel like one of the astronauts very quickly mentioned this as a possibility. Either way, an inhabitable black hole system is better than a system that is quickly becoming uninhabitable.

    New System 

  • Does the new solar system have 12 planets, a black hole, a sun and a worm hole all together?
    • I promise you there are stranger things in the universe.
    • They mention that the system they end up jumping out to from the wormhole is one with three planets; The other 9 planets either did not return pings, returned failure pings or were less valuable opportunities: They went after Gargantua because three beacons were still active in a single system.

    Romilly 

  • How did Romilly survive for 23 years on that ship? It was established that he didn't go into cryogenic sleep during the 23 years, so he was basically awake and functioning the whole time. Did NASA pack 23 years worth of food for this one mission(during a major food crisis I might add)? Wouldn't he have gone insane living completely alone with no communication with the outside world at all?
    • Romilly did sleep for long periods of time, just not the full 23 year stretch because he didn't know when they would come back and was afraid they never would. And it's clear it affected him greatly, seeming even more withdrawn.

    Cooper's Crashed Ship 

  • So, if Cooper is sending messages back in time through gravitational anomalies, does this mean that he's also the one who caused the anomaly causing the crash from his dream at the very start of the film? Why would he do such a thing? (Other than maintain the stable time loop).
    • He didn't. The 5th dimensional humans did. They needed him to "fail" to get into space so he didn't get sent on the Lazarus or similar missions before the Endurance.
    • Cooper stated to TARS while landing on Miller’s planet that the only time he crashed was when an AI decided to take over control while he was flying. It seems that is why he crashed, not from a gravitational anomaly.
    • Actually, he still could have crashed from a gravitational anomaly, with the AI taking control being a response to it.

    How Does Cooper See Anything in the Tesseract? (aka Gravity-Only Takes Vision For Granted) 

  • A more concrete version of the first few questions is: if They can only interact with our 3d world via gravity, then how did They create or transmit anything that Cooper could see with his eyes/brain while in the tesseract? Cooper appears to see lots of stuff in the tesseract. If They have the ability to make humans see things, why not create or transmit a huge image with the all-important equation on it? And make it visible to humans from a safe distance (either post-wormhole or pre-wormhole)?
    • Related to that, how does Cooper interface with the tesseract? When Cooper moves his hand in the tesseract to manipulate gravity elsewhere, how does the tesseract know where Cooper's hand is?
    • The tesseract creates some sort of band that connects through time and space to the items in the room (you can see this when Cooper is tapping the band connected to the watch when he relays the data to Murph).
    • Gravity manipulation could theoretically be used to create visual images that you can touch as well. The 5th dimension humans apparently still understand their distant ancestors enough to create interactive images of real events that a human can interact with, but not enough to just create a ready image of the gravity equation to transmit to Murph themselves.
    • In short, it sounds like They can capture Cooper through the black hole (or nearby "bridge" to the tesseract which is someplace in which a 3d human can exist but nowhere we can point to)—and only at that location—somehow. Once "captured," They can cause Cooper see things ...somehow. They can allow Cooper to manipulate gravity somehow, but They cannot manipulate gravity or 3d matter directly even though They can create a wormhole, a bridge for a 3d human, and capture and keep in a tesseract cage a 3d human. How can this sufficiently advanced civilization be distinguished from "whatever the plot needs at that moment?"
    • To me, it just seems like the 5D humans have completely forgotten ancient languages. They probably don't even communicate in text and sound any more whatsoever. So they know exactly what the equation is, but have no idea how to communicate it, and only sprinkle around "hints" for everybody to pick up: i.e. a wormhole that leads to a black hole and a tesseract that leads to an important person. It's like dropping a tablet on some ancient pharoah's lap with all the math necessary to build the pyramids, but you don't speak ancient Egyptian and he doesn't speak English. There's going to be a whole lot of Hand-Waving involved.
    • Except there would hopefully be no informational discontinuity between the movie's date and the quasitime of the fifth dimensional beings. We've got a lot better at accumulating information than ancient civilizations. And besides, can't they see the entire human history at once and create a method of backwards compatibility without requiring Cooper?
    • I was under the impression that the Tesseract is basically "Them" creating an interface that is effectively A Form You Are Comfortable With for their own level of existence. It's limited to Murph's bedroom and the film's timeline, but is effectively a control system of sorts to allow a human being who only has access to 4 dimensions (3 space, 1 time) to control gravity the way the 5D "Them" do.

    Leaving Earth with gravity 

  • Using data from inside the Black Hole, humanity managed to manipulate gravity enough to send enormous arks into space. But shouldn't the first option be to use this brand new technology to solve the Earth's problems, before abandoning the planet and traveling to an uninhabited planet in the same system as a black hole? How is living near a black hole safer?
    • Because you can't stop a crop blight with gravitic manipulation.
    • The solution for the gravity equation is very useful for moving large quantities of humans off the planet, Not so much for re-terraforming your planet to decrease its most abundant gaseous component to a level sufficient to retard crop blight (not to mention that the death of the biodiversity of the planet would make even a corrected atmosphere untenable for decades).
    • That being said, the logistic and technological challenges involved in fixing a planet's biosphere are still significantly less pronounced than space colonization. Especially considering that colonies wouldn't have anywhere near the manpower of Earth itself. There have been highly efficient methods of indoor farming that we are currently considering switching to even under normal climate, because they're better than what we have. Besides, having solved the problem of moving immense mass through space cheaply and efficiently, one could always change the climate via space-based factors, such as making ice asteroids melt on atmospheric reentry.
    • Colonization of other planets is a better long-term solution for the survival of the race than fixing a single planet's biosphere and staying there. If you remain confined to one planet then one disaster, like a big meteor strike, might doom the entire race. If we're spread over multiple planets in multiple solar systems one disaster can't wipe us all out.
    • Is it even show in the movie that they embrace some sort of big scale multi-planetary colonization? We only see humans living in a hugh space station and a colony in ONE other planet (Edmunds), presumably they did make other space stations, but as far as we know they did save Earth from the blight as Cooper (the daughter) is said to be living there.

    NASA doesn't know how time dilation works? 

  • Shouldn't NASA have known better than to trust a "thumbs up" ping coming from a planet with such massive time dilation? The readings would have only been a few minutes old from Miller's perspective, hardly enough time to do the detailed analysis of whether a planet so close to a supermassive black hole might not be suitable for habitation. And hopefully when they're first sending people out they're not just flinging them at planets and hoping they don't land on a lava flow. I'd hope they'd arrive in orbit and look for a safe spot to land. In doing an orbital survey, wouldn't Miller have noticed the enormous waves sweeping the planet and decided to give a thumbs down, or at least not transmit until further observation had been done?
    • They did a preliminary scan of all the worlds, found the twelve that appeared most likely to be suitable for life, and sent an astronaut to each. There were no other options. If Miller got there and realized the planet was less habitable, then they thought that before she even landed (which she might not have; the waves would have appeared frozen from her perspective) she would have had to land anyway to make sure, and then the time dilation hit. The "thumbs up" signal is just the most basic "The relay isn't destroyed and the astronaut hasn't said the world is unsuitable" signal. When the relay got destroyed, the signal didn't have time to propagate out and tell the others that something went wrong. As for the time dilation itself, the only explanation is that a bunch of very smart people were rushing and made a mistake, and never caught it until it was too late.
    • They also mention that Miller's planet was closer to Gargantua than they had estimated. As far as NASA knew when making their plans to investigate, Miller's planet wasn't being affected by a time dilation. You can only plan based on the data you have, and they didn't know they were receiving a ping echo. Had they only gotten the actual pings that were sent, they might have been able to figure it out.
    • Miller's planet may have been closer than anticipated due to gravitational lensing from Gargantua itself. With only the pings going back to Earth instead of actual data, they wouldn't know for sure until they saw it.
    • In the movie, it does seem like the characters are surprised by how close the planet is to Gargantua — as though this was information they did not have until arriving on the other side of the wormhole.
    • It was an Idiot Ball moment on NASA's part to evidently not include a date/time tag on the pings - relative to the ship's internal clock, of course, so it could be compared to passage of time on Earth.
      • It was explicitly stated during Cooper's briefing that getting data back through the wormhole was extremely rudimentary, mainly limited to very short binary blips. Presumably, an encoded timestamp would've been too complex to be readable.
      • Though, they are able to transmit audio and video in both directions...
    • Regardless, it's completely implausible that the pings made it out as they were anyway if time dilation would increase the interval between each bit of data greatly. Assuming the signal could make it out at all as something recognizable, anyone who receives it would be aware of the time dilation at signal's source.
    • All in all, what value would be to colonize a world, where for every subjective 100 colonist-years, in outside universe 6 132 000 years would pass?
    • Six million years isn't very long from an astronomical perspective. They just need a base of operations for a few hundred years to get ready to colonize somewhere else.

    The Arks on Earth 

  • The ark appears to be a giant, self-sustaining ecosystem that the people inside have been living in for years. If you can build that, why do you even need to go into space? Why not just pack as many people as you can on board, seal it off, and live there indefinitely on earth? Odds are the blight would run it's course eventually and some kind of new ecosystem would establish itself, which means earth could probably even be reclaimed.
    • The blight produces nitrogen, meaning that the new ecosystem would be something completely alien to humanity. Living inside the Arks without launching them is a short-term solution, but it can't last forever. That's why they're leaving for a new world instead of just sticking around. The Arks were never intended to last for more than a few decades, at most (it takes two years to reach Saturn, then a few more months to reach the new world, though the Arks might be slower than the Endurance)
    • Still, if creating totally self-contained habitats free of blight was an option all along, the ticking clock driving the entire plot pretty much falls apart.
    • Not really. The longer the self-contained habitats are on Earth, the greater chance of a breach and the crops inside getting infected. It's an answer that could last them a very long time, but it's not a permanent solution.
    • And in fact, it seems to be a short-term solution that they implement before the end. Murph tries to convince her brother and his family to come live with her in the NASA facility; he refuses to "hide in a hole in the ground" because it's only delaying the inevitable. On her way back to the base she passes a line of trailers loaded with people, their families and their belongings — presumably going to take shelter in the Arks.
      • Questionable. When asked what the fleeing people are hoping to find, she just says "survival." If they were headed for the arks - for which Murph is a senior official - it would've been a non-question. It's more likely that it's a re-enactment of the population movements during the original Dust Bowl: people unable to survive where they were, so striking out to find somewhere, anywhere they can make a living and survive. Thematically, it's also consistent with the film.

    The Waves on Miller's Planet 

  • Those waves, man. How do they work? Maybe this looks like a stupid question to a science major, but I really didn't get it. Why does the water look like an ocean if it's that shallow? How do those giant waves come out of water that shallow? And why were they moving so slowly?
  • According to The Science of Interstellar by Kip Thorne, Miller's planet is shaped a like a football with one end pointing at Gargantua. The waves are literally tidal waves, so it's not the waves coming toward you, it's the planet rotating under you and the fixed waves slamming into you. But because the planet doesn't rotate, the waves wouldn't slam into you. Fortunately, tidally locked planets can rock back and forth, and Thorne used this as a scientifically accurate loophole to explain tidal waves on a tidally locked planet. Also, because the water on Miller is mostly concentrated in the waves, you could have knee-high oceans, like the one shown in the film.
    • The water covers the entire planet, just like Earth after it cooled but before continents. On Earth, the moon pulls the oceans into tidal bulges, hundreds of miles across and minor. Since the black hole's gravity is so focused and much more powerful, this is taken to its Logical Extreme. Furthermore, without continents, there's nothing to stop the waves, so they just sweep around and around indefinitely. The extremely shallow water between waves is actually the equilibrium condition: the waves would keep getting bigger until the water got so shallow between the waves that they couldn't transmit properly any more, and then stop. Side note: this does not make the planet unusable. Just make all the buildings and greenhouses watertight, and go inside each time the wave comes.
    • Thank you. (OP here with a different handle, btw.) All the responses here have been really helpful but I feel like this one answers my exact question.
    • Don't quote me on this, since this is just taking what physics I know and using movie logic (ex. water is softer than rock so landing in the ocean from a great height is not fatal whereas hitting solid ground would be. Reality says hitting water from a great height would be like hitting solid concrete), but normal waves like we see on the oceans are created (I'm not sure if this is in part or entirely) by the gravitational pull of the moon on the water. The black hole has a huge amount of gravity, especially when compared to the moon. Using this logic, more gravity equals bigger waves.
    • They landed on the shallowest part. Have you... uh... ever seen a wave before? Generally there's a shallower part and a crest that goes above it. They were standing in the shallow part. And the waves weren't moving slowly, they were moving quite fast and were humongous, which is why you could see them from the horizon. And since many replies really make me think people haven't seen a wave before... have an explanatory image.
    • Thank you, but first of all, I don't need any of that presumptuous attitude. Of course I have seen a wave before. I was talking about the depth of the ocean. It seemed like they were walking on water—are you suggesting maybe that they were on some sort of coast? It seemed like they were landing in the middle of the ocean. Later I had this thought that maybe they really were in the middle of the ocean, but didn't sink as far as they would on Earth because of something to do with the gravity (I can't imagine what). However, it did look like they were walking on solid ground instead of dabbling in the water, as far as I remember. Though this is only what I remember from what I've seen in the movie theater once and I probably need to see the scene again to understand it better.
    • I think as mentioned above they were using the concept that strong gravity (and especially strong gravity variation) = huge waves. On the planet they were on the entire surface was covered in water and unlike Earth's ocean which may roughly vary from 2 miles deep in a wave trough to 2 miles + a few feet at a wave peak (making up numbers here), that planet's ocean varied from a few inches deep in a wave trough to a few inches + a few hundred feet at a wave peak. Honestly, I doubt the trough should have maintained such a constant depth between waves even in that case, but I think that's the idea they were going for.
    • Another factor is that there's nothing to break up the waves. On Earth, we have continents, islands, and other masses that prevent waves from getting too large. On a planet that seems to be almost entirely covered my water, the waves would simply keep building and perpetuating themselves until there is essential one or more superwaves just flowing across the surface. I think that's pretty much exactly what's happening on Saturn or Jupiter.
    • And with giant waves crossing the surface, you would get a lot of erosion making the planet almost flat anyway.
    • So, here's the deal. When waves happen, part of the water goes up, and an equal amount goes down. If the water were still, the surface level would have been the halfway point between the peak of the waves, and the trough (where they landed), so, y'know, the ocean would be roughly 5 miles deep? And, as prior comments have pointed out, the waves are so huge for two reasons: 1) the tidal effect from Gargantua's gravity being so, so many orders of magnitude higher than the tidal effect from Earth's moon. 2) No landmasses to break against.
    • One thing that doesn't have a solid explanation, however, is the fact that Miller's planet is still somehow NOT gravitationally locked to Gargantua. Given the mass difference, Miller's planet should've stop experiencing any asynchronous rotation a long time ago. And on a tidally locked planet (e.g. like our own Moon, which always faces Earth the same side), the gigantic tidal wave won't move anymore and will stay in one place relative to the surface.
    • It is grav locked and the planet is in fact shaped like a football not a sphere due to the forces pulling on it, but even locked planets can still rock around. This combined with the extraordinaire gravity is used as a viable loop-hole to explain the waves and tidal forces at play. This was explained in the first answer.

     Endurance and the Ranger 

  • So, apparently the Ranger is capable of Vertical Take-Off and Landing (VTOL). If they have the technology to build a reusable orbital vehicle with those capabilities, why did Cooper and Co. need to leave earth sitting on top of a rocket?
    • A rather large rocket, too. NASA apparently figured out a spacecraft that can launch from the surface of a 1.3g planet that's the size of a small plane, fuel included.
    • ... and still has enough fuel left over to land and take off from another planet afterward. It's possible that this fuel was stored somewhere aboard the Endurance, and that they refuel off-screen, but then we'd have to explain how the Endurance itself was capable of boosing itself out of and into so many planetary orbits, without any obvious large fuel tanks.
    • It seems to be a fuel-saving measure. By using a disposable booster to reach Earth orbit instead of its own fuel the Ranger gets to save its fuel for later landings and launches from other planets. It's one more trip to orbit's worth of fuel.
    • Planet landings are absolutely nothing compared to getting in and out of the black hole's gravity well to land on Miller's planet. The stated time differential of seven years per hour implies relativistic escape speed (almost the speed of light, as compared to meager 11 km/s to escape the Earth). Given overall hardness of Interstellar, it's a very blatant case of Artistic License – Physics.
    • It is also possible that they wanted the launch to be covert as in a VTOL orbiter would set off alarms that a satellite launch would not.
    • Maybe the Ranger runs on antimatter-propulsion. Because matter/antimatter-annihilation releases lots of energy, it's a very high-efficiency propulsion for when you can't afford to bring tons of fuel. It also would make it prohibitively expensive to synthesize more antimatter than what is absolutely necessary, making it cheaper to launch them into orbit via conventional means (i. e. chemical rockets) but use the high-efficiency antimatter-drive around Gargantua because they won't be able to bring much fuel (which is kind of the central problem in rocket science - if you want to bring more fuel, you also need to start with much more fuel to carry the surplus fuel you want to bring).
    • Whatever source of fuel the Endurance and its associated landing craft used, it appears to be in limited quantity, but has incredible energy density (hence speculations that it is a matter/antimatter reaction above). It is common to use fuel that is cheaper and has better thrust but less specific impulse as your first lifting stage, which is why solid fuel is often used as a first stage booster in the real world despite liquid fuel being more efficient. It makes much more sense if you understand the Rocket Equation.

     Endurance and Mann 

  • When Mann docks with the Endurance but forms an imperfect seal over the docking ring, it's implied that him trying to override the safety procedures and open the hatch to get inside would lead to a disaster. As it happens, he attempts this and causes an explosive decompression which rips apart his ship, kills him, and damaged the Endurance. In the first place, how could Mann not understand something like that would happen? Reckless as he was at that point, he wasn't trying to get himself killed. And secondly, why didn't he depressurize the airlock before opening it? No air, no explosive decompression. In fact, he shouldn't have even needed to dock at all, after he got close enough he could have just exited the ship and EVA'd over to the Endurance's airlock.
    • A reasonable assumption is that Mann has gone more or less off the deep end due to his extended isolation; from the moment of discovery, he could even have copped to the fabrication (or claimed that his initial data was incorrect, or that circumstances on the world had worsened while he was under, or any of a host of lies), and thus left the world with the others for Edmunds' world without ever killing anyone. In essence, it seems to be a combination of acute paranoia (combined with the fact that they had disabled the autopilot remotely; who's to say they weren't somehow feeding the Ranger systems false data to keep him from taking the Endurance?), and an undue amount of haste caused by attempting to board the Endurance, familiarize himself with any changes made to the systems since his departure from Earth, and escape before Cooper and Brand could themselves come on board and stop him.

     The Decaying world on Earth 

  • A blight is consuming all the oxygen in Earth's air. Over 99% of the human population has starved to death. Yet aside from the occasional dust storms, life seems to be going on as usual. The Coopers' farmhouse still has running water and working electricity. Who's running the power plant? People still drive their cars everywhere. Who's drilling for petroleum? Who's refining it into gasoline, and distributing it to the gas stations?
    • During the hunt for the Indian drone, several wind turbines can be seen. So those are providing electricity. The cars (Though their models may be older) are probably electric as well.
    • It seems likely that robots and advanced automation are running the power plants, drilling for petroleum, refining that petroleum into gasoline, etc. Cooper's own farm is mostly being run by completely automated combines and tractors, with the humans just handling what the robots and machines can't.
    • The fact that they're still using contemporary (to us) vehicles and equipment many decades in the future implies a sort of Used Future. Manufacturing probably fell by the wayside, and with several orders of magnitude fewer humans alive, resources such as petroleum are not expended nearly as quickly. Cooper mentioned high-grade solar cells on the drone he captured, implying it could power an entire town.
    • We also never actually see them fuel their vehicle, given everything else mentioned in the above two comments, it seems likely the cars would be running on pure electric engines, just so that resources wouldn't have to be wasted on refining petroleum.
    • Except we actually see the Murph using some clearly flammable liquid to burn the crops in order to distract her brother. Of course she could have the canister of that mysterious liquid in her car just in case she needs something flammable to play a prank on some poor farmer.
    • Where did you took the "99%" of humanity starved to death? is never established in the movie, not that percentage at least. On the contrary, if there's enough population for the government to have to make secret the existence of a space exploration program in order to avoid public outcry is because there's enough people to have a normal society in which democratic elections are still held and public authorities still have to worry for public rioting.

    Livestock 

  • So wheat and rice have died from blights, and corn soon will as well. What about livestock? With the population way down, there's enough land to produce enough meat to feed everyone. In fact, grow alfalfa - which fixes nitrogen - and feed that to the animals.
    • Alfalfa, hay, and other fodder for livestock may have also already died from the Blight.
    • Speaking in terms of calories, raising livestock is inefficient. You feed them more calories worth of corn, wheat, or what-have-you than you get out as viable meat. So when agricultural issues started happening, livestock were probably gotten rid of early on, so that their feed could be used to minimize human starvation.
    • Keeping livestock alive through the winter requires easily-stored animal fodder, which is usually grain-based. Grains aren't just a vital agricultural resource because they generate a lot of calories per acre, but because they can easily be stored dry for long periods.
    • During the baseball game Donald's longing for a hot dog heavily implies that there are no more hot dogs, presumably because there are no more livestock to make them from. In fact no animals of any kind appear in the movie, not even a farm dog. Probably all the animals were eaten when crops began to fail to the Blight.

     Gravitational Slingshot Around Gargantua 
  • To save fuel getting from Mann's planet to Edmunds' planet, our intrepid heroes slingshot around the black hole. A real gravitational slingshot — such as the one the Voyager probes performed with Jupiter on their way to Saturn — only works if the object you're slingshotting around isn't the object you're orbiting. A trajectory that takes you from one planet to another is, by definition, an orbit around the star (or in this case, the black hole). A close pass by the black hole wouldn't actually give their orbit any extra energy.
    • Sure they can; check out this on powered slingshots. As mentioned in the limits section, the reason we currently don't is the inability of our craft to withstand the heat passing so close to the Sun.
    • The original objection is still valid. Using the Sun to perform a gravitation slingshot is only possible for a space craft entering the Solar System from outside. In the film, they had already landed and remained stationary on Miller's planet, so they couldn't use a gravitational slingshot from Gargantua. A powered slingshot would be possible, but would require fuel, which was exactly what they needed to preserve. The better explanation is that they weren't actually performing a gravitational slingshot (which wouldn't have required losing any mass to the black hole), but making use of a different method to gain velocity from a black hole, based on the Penrose Process.
    • They did use a powered slingshot. The used the remaining fuel from the lander and from one of the rangers. They also lost the mass of the lander and the ranger, so the Penrose Process was being used, as well. It doesn’t seem to be an either/or situation, but rather that they are using both methods.
    • It is, in fact, utilizing the Oberth Effect (see "powered slingshots" above), albeit in a single pass rather than over several close approaches. The basic principle is that it requires less delta-v to change the eccentricity of the orbit (how stretched the ellipse is) when travelling at higher velocity (such as at the periapsis, or closest approach, of the orbit), and raising the eccentricity to 1.0 is what is required to escape a particular gravity well. (Conversely, plane changes are easier at slower velocities.) Cooper had inadvertantly put the Endurance onto a close approach to Gargantua in his attempt to escape the atmosphere of Mann's Planet, so he utilized that to escape. Jettisoning the two landing craft ( along with Cooper and TARS) provided mass reduction through the Penrose Process, much like staging a rocket launching from Earth would, but the primary factor in play would be the Oberth Effect.

     Tom's son 

  • So Tom named his son Coop Cooper?
    • Yep. There's a reason his wife shot the idea down originally. Or, alternatively, he named his son Joseph Cooper, and then called him by the same nickname.
    • Wouldn't be the first time. The former announcer for The Price Is Right was named Rod Roddy.

     Earth and Humanity's Future 

  • Murph has worked out the equations so Plan A/Cooper Station can work, and they might be able to colonize Edmund's planet in the future. So what about Earth. Did Earth recover? Or did it die and we only have Cooper Station now?
    • There doesn't seem to be any way to stop the blight, so it seems that Earth did not recover, and most of humanity moved on to Edmund's planet. There's no reason to think Cooper Station is the only station, though.
    • The doctor specifically mentions that Murph is transferring from another station. Presumably she didn't feel like living on the one named after her.

     The Blight and the Space Stations 

  • One thing I don’t understand is why escaping Earth helps humanity escape the blight. Presumably, any vegetation on the space station arcs sent into space would have contracted the blight as well. Meaning humanity is just bringing their problem with them to their new home planet. The only possibilities that I can think of are that there are pre-blight seeds in hibernation kept away from outside exposure or that there are greenhouse farms such as the one at NASA that are kept as far away from outside exposure as possible to prevent contamination. Did the movie address this at any point?
    • The movie didn't address it, but the most likely explanation is a combination of having pre-blight seeds on ice, and having the ability to filter the air and the soil they're bringing with them to make sure it doesn't contain whatever microparticles cause the blight.
    • The stations are effectively climate controlled, complete with air filtration. It would be impossible to filter the entire Earth's atmosphere simultaneously, so the only solution would be to let the Blight consume everything and die of its own starvation. Perhaps several centuries in the future, Earth could be re-terraformed into a habitable planet again and re-seeded with flora from the stations.
    • Another explanation is that the space stations use a different gas than nitrogen for their "air". As long as oxygen was still mixed in with similar proportions to actual air, it should be viable. Some deep SCUBA diving gear will use helium or neon in place of nitrogen (to prevent nitrogen narcosis), so it is theoretically possible with some other elements.
    • They probably made use of the Svalbard Global Seed Vault - we already have a large variety of different seeds in Norway's permafrost, obviously unaffected by the Blight. Transfer the seeds (or half the seeds, if you want to be careful) to the arks, then scaper off into space with tons of goode olde Blight-free seeds ready to use in your space station/new home.

    Cooper's personal timeline 
  • The movie begins with Cooper as a test pilot. In the scene at the school he says he's an engineer (among other degrees). But later his father in law says that Cooper never got the chance to use his degrees. Then at the baseball game, Cooper mentions that when he was a kid, people were rioting for food instead of going to baseball games. So exactly when did everything start going south on Earth? If things were so bad that there were food riots in America when Cooper was a child, then how does he go on to acquire several university degrees when society was becoming so unstable?
    • The collapse of society has been a gradual one, and probably with ups and downs. The food riots in Cooper's youth were apparently not enough to prevent him from acquiring degrees in young adulthood. His father in law says he wasn't able to use his degrees because he only went up once, and then the space program was publicly cancelled. It's quite possible that there were bad food riots when he was a kid, then things stabalized for a while during his college years, and then fell apart even worse after he joined the space program.
    • Food riots tend to happen long before starvation, when society starts to have a sustained malnourished population. Things wouldn't have had to go down and up and down for Cooper to have finished school after food riots in his youth, they could have been in a slow, steady decline.

    What's with all the American Flags? 
  • I get that this is NASA, an American run program sending Americans out to do it but come on guys. This is to save the world. It isn't some race like in the cold war. Couldn't they have made an Earth flag showing the globe to put up base on these planets except for the good ol stars and stripes? More an IJBM than a Head Scratcher but I'd still like to know if there's any reason or policy for it. Near as I can see, current space programs are quite the joint effort in the modern day.
    • For all we can tell from the movie, every nation on Earth is completely extinct except the USA. One possible cause for this: Corn is, apparently, the last food crop on earth to survive the Blight. Corn (or rather, maize) is native to the Americas. It's possible that it was not widely grown enough in other countries to save them from starvation when the other crops failed.
    • Also there isn't any "Earth Flag" currently. Spacecraft today bear the flag of the nation that built them, and astronauts today consider themselves representatives of their home nations and generally wear the flag of their nation on their uniforms. Since the movie features American-funded and controlled missions featuring American astronauts, they use the flag of the US.
    • Whether or not other nations still exist, America is the only one hubristic enough to spend resources on anything but immediate food needs.
    • It might also be simply the case that they've kept using the American flag because it's already on much of the machinery, or out of habit. Given the state of the world that we see it in, it's unlikely that changing the flag was high on anyone's list of priorities.
    • Also, simple visual shorthand. The American flag on the moon is probably the most famous and evocative image we have of space colonization, and the average viewer isn’t going to stop and ask why they didn’t change the flag to something more universal now that the space race is over. Creating a whole new “Earth flag” to use in the movie would require at least a sentence or two of in-universe explanation, while using the American flag does not.

    NASA's shutdown 
  • Professor Brand states that NASA was shut down when they refused orders to drop bombs on large population clusters (as a short-sighted panic measure to curb mass starvation, we can only assume; or perhaps to quell mass riots.) Why would the U.S. government be asking NASA to drop bombs when it has a near-endless supply of its own bombs and planes in its military?
    • The time frames aren't discussed much, but weren't all armed forces disbanded at some point? Also, NASA had the capability of doing orbital bomb drops instead of just in the air.
    • It is possible this was a sarcastic remark regarding NASA becoming unpopular and losing funding, as it did not contribute to armed forces struggling to maintain order against other nations.
    • Brand specifically mentions that NASA refused to bomb the population from orbit.
    • It's also worth noting that orbital weaponry doesn't actually fall under the bailiwick of NASA, but rather USSTRATCOM. It seems very improbable that space weaponry would be put under the command of a civilian institution when military institutions exist, so any such event would have to take place after the disbandment of the armed forces.
    • Most likely explanation is that as the world started collapsing, the US government demanded that NASA turn over all its resources to military control in exchange for continued funding / existence rather than remain as a separate civilian organisation, which would no doubt involve using NASA resources and facilities for military purposes (i.e. bombing people from orbit). NASA refused, and so the plug was pulled. Brand is simply offering a simplified version of events for the benefit of the audience.

    Cooper's survival 
  • How did Cooper survive crossing the event horizon of a black hole — a region of gravity so strong that even light cannot escape — without being either squashed to a paste or spaghettified by the gravitational forces? He seems to take less harm from that than Dr. Mann did from the g-forces during the docking spin.
    • The short answer: Extremely fast rotating black holes allow to cross the event horizon without being torn apart. For the long answer in expert terms read here under "Comments: On the last act of the movie".

     Combine harvesters going wacko 
  • It's a minor thing, but why exactly did the combine harvesters go crazy? I'm assuming it was something to do with the gravity weirdness that resulted from Cooper's various attempts to communicate with Murphy affecting their navigational circuitry, but was there any more in-depth explanation offered?

    • The harvesters relied on GPS compasses for navigation. As I understand it, GPS recievers measure the time difference between when the signals from various satellites are sent and when the reciever recieves them to determine how far away they are and obtain a position. GPS has to correct for time dialation between the harvesters on the ground and the GPS satellites that occurs because the harvesters are deeper in the Earth's gravitational field. These calculations likely didn't take into account the gravitational anomalies, which would have altered this dialation and by extension the travel time of the signals, so the positional data given to the harvesters was probably innacurate. If the 'return to base' behavior wasn't intentionally brought about, perhaps the harvesters verify their position with other harvesters every now and then, and when one goes out of sync too often, it gets sent the command "go back to the house so Cooper can fix you" to avoid going too astray and running amok in someone else's field.
    • The gravity annomaly in the bookshelf seems to affect the sensors of the harvesters. That this sensor error causes them to go to the house instead of driving into random directions is probably just for dramatic effect. The same annomaly also made the spy drone descend close to the ground after having circled for a decade at high altitude.
    • The machines returned to the house because they detected an error in their navigation system. It's a simple error-handling routine. "If something is wrong, return to base."

     Communication through the wormhole 
  • So the wormhole allows them to send video feeds from Earth to the other side but only "binary pings on an annual basis" back. Firstly, what method of communication allows you to send 1 bit per year and no more? You can't send any ID of yours, no nothing, there are distortions in the way and you can't with certainty be online at a specific time. So, how can you send exactly one bit in this situation? Secondly, if you actually can fly back through the wormhole, why wasn't there a ship right nearby to receive detailed messages from Lazarus missions, then fly back through the wormhole and relay them to Earth?
    • It probably has more to do with the Lazarus mission hardware than it does with the wormhole. Earth can send reasonably hi-resolution full video through because it has really powerful ground-based transmitters, while the Lazarus missions had to use much more portable transmitters running off of limited power sources.
    • But I still can't think of any method of communication which will allow you to compensate for weak transmitters by reducing bandwidth to 1 bit per year. Even if you just start transmitting a very simple message on one frequency, you'll probably either never get through or get through much sooner than in a year.
    • Maybe its compensation for limited power sources. If you transmit only 1 bit per year that's a lot less power than transmitting full video.
    • Secondly, there are no other ships and no other astronauts to crew them, so a relay system isn't really workable. NASA basically sent everything it had on the initial Lazarus missions except for the Endurance, and Endurance had to be saved for "Plan B" when they knew the results of Lazarus, so it couldn't be used as a relay. They didn't even have another crew ready when the Lazarus missions were sent out.
    • Well, if they sent one less ship on a Lazarus mission and used it as a relay instead, they'd get one less shot in the dark but immensely more information from the remaining ships. After all, in the end they had no shortage of A-OK signals, just no means to investigate them all.
    • It must have been a choice between "check out one more planet" and "get more overall information", and NASA preferred "check out another planet".
  • Also, by the way, how much data did the Lazarus missions send? Some explanations on the Internet say it's exactly 1 bit or maybe several bits. But then Brand said "Edmunds' data looks more promising", which means there actually was enough data to judge if it was promising or not.
    • They only received more of Edmunds' data after they were through the wormhole, so for whatever reason it seems only the "pings" could make it to Earth, but more detailed info could apparently be transmitted within the Gargantua system. Maybe Endeavor had to send a "send your data now" signal when they came in-system to get the more detailed report.
    • They specifically say that there's a relay station that cached the data it couldn't send through the wormhole.

    The Watch 

  • Why did the watch keep ticking the code after it had been moved from the bookshelf, and how did Murph get the whole message after she picked it up? Cooper manipulated the gravity, which made the hand move... then what? He seemed to only be able to manipulate things in the room, and only at the points where he actively did so. Did he keep sending the same message over and over, moving with the watch? Did it somehow repeat? Why would a hand, stuck by the gravitational anomaly in the room, stay stuck in such a pattern wherever it was moved?
    • My impression was that Cooper was programming the watch. That way it would repeat the message over and over again. When he manipulated the "thread" that hung over the minute hand, that transmitted the data, and presumably the same thread would move with the watch. Cooper was in a fifth-dimensional construct in A Form You Are Comfortable With - the ones responsible for the tesseract would see what he did and make sure that his "programming" stuck with the watch so that humanity could be saved.

    Plan B 

  • It was pretty much handwaved in the movie about the ease of setting up a colony just using the frozen fertilized eggs. All they stated was the problem of genetic diversity but there would a lot more problems before it got to that point. Just how they were expected to grow the eggs to development, and then birth them, and then raise and feed the newborns on their new planet was never explained. Was Brand was expected to carry them to term on her own, or was their space station equipped with artificial wombs? In any case, hope they also thought to pack enough diapers and baby formula on that station, along with the birthing machines and be prepared to educate them all about surviving on the new planet, because they definitely won't find those necessary things on their new planet. What was Mann's plan, steal the space station with the fertilized eggs on board and head to the last planet, and then be tasked with raising and caring for 5,000 newborns into adulthood all on his own? That would be an hilarious scene; Mann cradling newborns as they come out of the machine, tasked with finding nutrients for them and changing their diapers.
    • As was discussed above, Mann was crazy. He didn't really have a rational plan in stealing Endeavor. The other problems aren't really discussed in the movie, but Brand does seem to be doing pretty well at setting up things by herself at the end, judging from the buildings she has up already. I think we can assume that they did have provisions for artifical wombs, raising newborns, etc. Maybe the first step is to set up a TARS-style robot factory.
    • Uterine replicators. As mentioned in the info dump about Plan B, the first generation would consist of 10 humans. And in thirty years they could have a colony with a population numbering in the hundreds.
    • ^ Yes, the eggs were never suppose to be use inmediatly, they where suppose to be use in the long-term once the population reached certain number, after several generations.
    • They planned to incubate ten eggs and use that first generation to start repopulating the human race naturally. With each subsequent generation, a number of the frozen eggs would be introduced into the population via surrogacy in order to maintain genetic diversity. Brand forecasts that this method will eventually lead to a baby boom and that the population will grow exponentially.
      • More likely they'd incubate ten female zygotes to maturity, then they'd act as surrogates for the next few dozen frozen ones.
      • Incubate the eggs using exactly what? Was Brand supposed to be the mother?

    Robot Soldiers 

  • The robots in the film seem perfectly designed for their effective role as multipurpose utility units for spacecraft maintenance and space exploration, but we're explicitly told that the same model used to serve in the marines. Does that kind of structure really lend itself well to modern warfare? There doesn't even seem to be a way for the robots to hold a weapon, not to mention move around the battlefield in any proper way or take cover from enemies. How was that supposed to work?
    • When they were combat robots they probably had their weapons hard-mounted, not held in their limbs. TARS still has some kind of taser mounted in him. They probably would be better at taking cover than a human, since they can completely flatten out to just a slab on the ground in moments. Plus they can do the "spinning starfish" thing to move at high speeds over relatively flat ground.
    • While the models used may have served in the marines they may or may not have been marines themselves.
    • Chances are NASA removed his weapon-systems when they got him and replaced it with a taser.
    • They are also shown to be startling quick even without turning into a spinning wheel. TARS is shown running out of the aftermath of Mann's trap at a pace comparable to a human, possibly quicker, despite the rough terrain. It's safe to assume they only move slowly most of the time because they simply have no cause for speed. They're also shown to be extremely strong, capable of moving chunks of metal comparable to them in size. If they are armored against small arms fire then they would essentially be a small, walking tank that can think. Not something you would want to encounter in a combat situation.

     TARS' decision-making 
  • TARS makes the autonomous descision to disable the auto-docking sequence on the landers and CASE knew about it, which basically falls under Zeroth Law Rebellion. If Mann had remained sane and this measure unnecessary, would they have ever told any of the humans that they did it or just activated again without informing them of it? What other safety precautions might they have taken to make sure the humans don't jeoperdize the mission? And if Mann had been able to order them to do it, would they have had to comply or do their make their own judgements about who is in a mental state to make rational descisions?
    • I'm guessing TARS wouldn't have disabled auto-docking if Mann hadn't made off with a Ranger after blowing up KIP and Romilly and attacking Cooper. It seems like a military robot in the future might have some recognition of tactics and patterns and recognize when someone was trying to seize a position of value. It would also follow that it would have a directive to protect it's companions (the Endurance crew), and possibly recognize Mann as being emotionally unstable and deferring leadership to the others. Coming from a robot that can tell jokes, recognize when not to reveal information, et cetera, this isn't too farfetched.
    • TARS disabled auto-dock before Mann stole the Ranger. I think CASE was suspicious of KIP's deactivation, or other subtle cues that Mann wasn't quite right in the head.
    • Pretty much. TARS and CASE didn't communicate that they found Mann's story suspicious because they weren't sure (90% honesty parameter!), but did enact a safety measure on their own, just in case they were right.

     What Makes Miller's Planet a Viable Option At All? 

  • Maybe it's because desperate times called for desperate measures, so they needed every choice they can get. But by common sense, shouldn't any planet that close to a black hole equals bad thing? What's with the extreme gravity from the black hole that will most likely mess up the environment or evolution on the planet, as well as the time dilation itself. Even if Miller's planet can be settled, the extreme time dilation means that by the time the astronauts set everything up, people on Earth will probably be already dead? All in all, Miller's planet seems like a poor choice to colonize.
    • NASA knows next to nothing about any of the worlds until Endurance goes through. All they have to go off of initially is the binary pings that made it through, and estimates based on observations made from looking through the aperture. When Endurance discovers that Miller's planet is close enough to experience Time Dilation, they decide to move forward because Dr. Miller was broadcasting a thumbs-up signal, and they didn't have the resources to return to Miller's planet later on the off chance that the other two worlds didn't pan out. If Miller's planet was suitable for life, colonization prep would probably work the other way around; just send the masses of people into low orbit, where (to observers outside of the time dilation zone) they consume next to zero resources, and much of the time-consuming prep could be done outside of the time dilation zone. Hence, their decision was a desperate measure taken by a small group of intelligent people trying to decide the best course of action to save the entire human race.
    • Even if planet Miller is perfectly capable of sustaining life, why don't the astronauts have some doubts about the nearby black hole? Granted, the planet is still fine so far, and time dilation isn't really much a problem, but they don't know whether in the future the extreme gravity might do something to the planet. Black holes are known to be capable of producing such strong gravity force they pull entire stars into them, not to mention the various asteroids or space debris that will get pulled into the planet. Desperate measures or not, it seems pretty suicidal to live on a planet near a black hole, no matter how perfectly habitable it is.
    • Black holes aren't really much more dangerous than stars. In any case, the fifth dimensional future humans chose to link their wormhole to a system with a black hole because their real objective was to get Cooper inside, and there had to be habitable planets in the system so that he would come near the system in the first place. It wasn't chosen as the "best" possible future home for humans.
    • But the present humans didn't know that yet, right? All they know is that they are desperate for a new home to live, and I guess that's why they chose to explore planet Miller despite all the risks it seems to possess. It was the astronauts' choice to land on planet Miller, even if it was predestined to be by the future fifth-dimensional beings. And in doing so, they got one of themselves killed and wasted 23 years worth of time due to the time dilation without gaining anything useful.
    • They didn't go down to Dr Miller's planet because they thought it was viable, or as viable as the other two. They went down there to rescue Dr Miller, unaware that she was dead. Any info they wanted to gather on her findings was more "for future reference", perhaps to colonize it after Mann or Edmunds'. As to why Dr Miller herself gave it a thumbs up or was sent there, it's because she didn't and couldn't know whether the other astronauts on her mission had found suitable lifeforms or not, and for all she knew this time-dilated world was the only one capable of sustaining human life for any length of time.
      • And Miller didn't actually gave a thumbs up. She approached the planet, probably saw the water, and send an "OK" to show she was still alive and that the planet had water. Then, she landed, she died from the wave, and planetary seconds after, the main characters landed. It was all due to the time dilation that her first OK kept being repeated while going out of the atmosphere.

     Never send a robot to do a human's job? 
  • Why does Amelia Brand go for the black box data on the ocean planet? In saving her ass, the robot proves it was quite capable of going and finishing that job while she ran back to the ship. Serious Idiot Ball there.
    • Dr. Brand is smart and received the best training available, but she is inexperienced. She was simply too focused on doing what she felt would complete the mission and not accustomed to following orders.
    • Cooper immediately calls her out on that and calls the scientists completely unprepared for this kind of mission. The movie fully acknowledges that these action were stupid.
    • She gets only a mild rebuke considering her delay in getting back to the ship got a fellow crew member killed. And it was all for nothing!

     On blights and oxygen deficiencies. 
  • So a blight, or perhaps a series of similar blights, is taking out the world's food crops (wheat, okra, and maize mentioned specifically). This is obviously a problem, but not an insurmountable one. There's enough biodiversity among staple crops, not to mention aquatic sources of food, that it's unlikely to doom humanity. But, oh no, now we're being told that when the blight is done with corn, people are going to start suffocating because there won't be enough oxygen in the air! But hang on. The blight, as far as we've been told, only affects human-grown crops, not the entire Plantae kingdom. And even if it did affect all land-based plants (highly unlikely), around half of Earth's atmospheric oxygen, if not more, is produced in marine environments, by e.g. algae and cyanobacteria. It is a very extreme stretch to say that running out of maize = running out of oxygen. So why did NASA scientists, who really ought to know better, present that as the definite outcome?
    • Perhaps there are factors that don't come up in the movie, like pollution of the marine environments having already caused serious damage to the production of oxygen there.
    • Dr. Brand says that the atmosphere is 80% nitrogen. In reality, it's closer to 70%. But our oxygen is produced by plants, so if the blight has also hit other plants, then global oxygen levels could be falling.
    • The dust storms are the aftereffects of desertification; couple that with the mention of the lack of rain and it's fair to assume most vegetation has died off. But no it doesn't explain why ocean algae and Phytoplankton (both of which produce more oxygen than land plant-life) are unable to keep us from suffocating.
    • I was under the impression that Blight actually eats oxygen, in addition to eating nitrogen. If that's true, then a sufficient amount of oxygen-destroying Blight could overpower the oxygen-producing plants that remain.

     How did they escape the time dilation planet? 
  • The first planet they visited had time passing 60000 times slower than normal. This would also mean that to escape the gravity well they'd need to get kinetic energy 60000 times their mass energy. Given how the rocket equation works, the fuel ratio has to increase exponentially to get more delta v, so they'd probably need more fuel than exists in the universe.
    • They're not using rockets, but some kind of air-breathing turbofan, which uses the atmosphere of the planet for reaction mass. Outside the planet, there's sufficient matter in the accretion disk of the black hole to continue in this mode.
    • They additionally mention that they passed a neutron star to slow their descent, so perhaps they used a slingshot around it to get back up again.
      • It’s artistic license. Dipping in and out of that gravity well would cost thousands of Earth years, no matter how they did it. Also, Miller’s signal would have been Doppler shifted far beyond recognizably. If NASA had even tried to prepare for this signal, they sure as heck would know right away of the time dilation.

     The Miller Landing 

  • Here's what I don't get: during the landing sequence, we're given multiple glimpses of the horizon in all directions and there's not a wave in sight. All that can be seen is an open expanse of water. Yet, they're on the 'ground' for little under two minutes, when suddenly, there's this big ass wave that's slowly advancing towards them, that nobody saw coming, until it was staring them right in the face.
  • How is that even possible? At that size, shouldn't they have seen it coming as they were flying across the surface? It'd be like failing to spot The Great Wall of China, despite flying right at it. And how do they appear so suddenly, if they move that slowly?
    • Cooper was in a big hurry to get down, get the data, and get out fast. They didn't take any time sight-seeing on the way down to Miller's beacon. They did see the wave before it "suddenly" appeared - they just mistook it for a mountain range until it got closer.
    • The Ranger landed quickly under heavy cloud cover. If they were looking at the surface at all, they would only have seen glimpses of it until they had landed. As mentioned earlier, they were rushing to grab the data and leave.
    • According to the behind-the-scenes extras, the waves on Miller's Planet topped at 4,000ft high. No matter how big a hurry they were in, there's no conceivable way they should've failed to spot something that size as they were flying towards it. When Cooper lands, he banks the Ranger so the rearward hatch was facing in the direction of the approaching wave. Meaning, Brand and Doyle should've seen coming it the moment they stepped out of the shuttle, yet there was nothing there. If you pause at 1:54 of the behind-the-scenes video, that's exactly as the horizon appeared right as they first exit the shuttle. So it seems odd that these waves can appear seemingly from thin air, despite how slowly they appear to move.
    • The waves are both extremely large and extremely wide. Land mountains are noticeable because they stick out and are pointy. While landing, they didn't exactly take survey tools to make sure the horizon wasn't as perfectly round as they expected it to be. The wave WAS the horizon. It was only after walking around for 20 minutes or so that they noticed the horizon was suddenly a whole lot closer than they remembered.
    • After rewatching the clip, I have to say, you were right. At about 0:47-0:49 of the wave scene video, you can actually see the wave approaching in the distance. You can just faintly see the water rippling along the crest of it.

     Lazarus Landing Pods 

  • Why did the Lazarus missions bother with using Landing pods? They get torn apart / crushed fairly easily (at least Millers' and Edmunds' do) and they are already arriving on the planet in Rangers, which are durable enough to survive being pummeled by superwaves. Did they not have any way to rig their Rangers with a hypersleep machine and an appropriate set of supplies?
    • Did the Lazarus missions use Rangers? I don't recall anything showing they did. Maybe the landing pods are cheaper alternatives to Rangers, allowing them to build twelve of them instead of the two that were left to put on the Endurance at the time of the movie. Just about anything would fall apart if it got repeatedly smashed by a 200-foot tidal wave (Millers') or a big enough rock slide (Edmunds').
    • The Lazarus Missions were 'Twelve Ranger Launches', according to Professor Brand. Perhaps the Rangers were sent to the wormhole, but they separated from the landing pods, returning to Earth, while the landing pods traveled through the wormhole to their respective destinations. This would explain their absence on the planets Endurance visits.
    • Brand says that the metalic materials use in their projects is "one less bullet shot", so yes, probably they were using the military budget.

     NASA's Post-Apocalyptic Budget 
  • Where in the corn-eating dust-ridden no-army-having world would NASA get the money to build 14 rangers (12 rangers for the lazarus missionz + 2 for Endurance), 12 landing pods, 2 landers, one Endurance, and several colony ships, given that most of this equipment was a secret? Were these equipment salvaged from NASA pre-shutdown (given that we know that the Rangers were being tested years before at the decline of NASA) or were they all cobbled together in secret and funded at the government's expense?
    • That was the point of Coop complaining about his tax money. The government gave NASA what would normally be the military budget, since there are no wars any more.
    • As above, did the Lazarus missions use Rangers? I don't recall any sign that they did. The Rangers used by the Endurance may well have been leftovers from before the blight, like much of the rest of the technology used in the movie.

    What Direct Evidence Exists That "They" Are.... 

  • ...future humans? If memory serves, all we have are Cooper's speculations. Wouldn't it make sense that They cannot be future humans because, you know, it is a contradiction that your 60-year-old self saved you from being hit by a piano when you were 50? Doesn't "advanced aliens saved humans" make more sense than claiming "stable time loop—end of discussion?"
    • We know they're from the future at least, since otherwise they wouldn't have bothered sticking to gravity.
    • Well we know there's a Stable Time Loop, because first Cooper sees the dust-message and then later on he personally creates that same dust-message at that same point in time. Once we've established that future-Cooper sent past-Cooper to NASA, it's not hard to imagine that the entire scheme is a case of future-humanity helping past-humanity. But yeah, there's no direct evidence of that.
    • As mentioned before, there is the possibility that this is a Multi-verse. Let's assume there's a parallel Earth with no blight, humans evolved there normally and became Energy Beings in the fifth dimension, now they can see all different universes and help those where humanity get extinguish for some reason. That or in the original timeline some humans did manage to survive somehow (whether hidden in bunkers waiting for the Blight to kill itself once no more plant life and/or oxygen is available, and then rebuilding the world using the seeds guarded in Norway for this kind of scenarios).
    • Stable Time Loops are more logical and simpler than time travel that can alter the past. They seem to be uncomfortable for many people to think about because humans are used to thinking in cause-effect chains. Really, there's no contradiction. You just have to let go of the idea that the cause-effect between A and B can only go in one direction. Your old self can save your young self from dying; your old self exists because when he was young he was saved by... his old self. There is only one timeline. It's all consistent. It's just unfamiliar, but so is a lot of physics.
    • If the Bulk Beings were a benevolent alien civilization that just wanted to save us, they would have done so in a more direct manner. The circuitous, seemingly obfuscating way they help is because they have to keep the stable time loop... well, stable. Things have to happen certain way because their existence too depends of it. Think about it, the Bulk Beings give the secret to manipulate gravity, which most likely was the first step that would eventually lead humanity to transcend into the fifth dimension and become the Bulk Beings.
    • To be fair, the hypothesis that the fifth dimensional beings were the future of humanity speaking into the past was never confirmed outside of Cooper's guess, which means that the actual truth is still ambiguous. They could have been Sufficiently Advanced Aliens with Cooper just being mistaken. However, the issue of a Stable Time Loop is not ambiguous because Cooper himself was involved with it. Thus, whether it was a transcended humanity or Sufficiently Advanced Aliens, a Stable Time Loop is involved.

     Why Saturn? 

  • Of the places in our solar system, why would "they" choose to place the wormhole near Saturn? That's pretty far for a manned flight to try to reach, we're talking months worth of fuel just to get there - nevermind the rest of the journey afterward. So why not choose a closer planet, like Mars for example?

    • I know this is being pedantic, but it doesn't necessarily take months of fuel for a trip to Saturn. We have Newton's First Law to thank for that; given a strong push in the right direction, Endurance could go a long way without using a lot of fuel. It also helps that Endurance used a gravity-assist to swing around Mars to gain the velocity to reach Saturn. The real trouble, of course, was that this journey takes 2 years, but cryosleep mitigates this for the astronauts. That being said, I have a few thoughts:
    • We don't know what the limitations of the technology that They, the Bulk beings, have for creating wormholes. Space may seem like it's all the same to us, but They live in the Bulk. While the Bulk Beings appear to have the ability to create a 'window' in anywhere in our universe (for example, Murph's bedroom), it's still a limited system; light travels over to them, and gravity travels back to us. Creating a wormhole is probably much more involved; it's essentially pulling two separate points of space together so that not only do they connect, but they remain connected long enough for a baker's dozen manned missions and a few space colonies to travel through in the course of a century or two. Maybe Saturn was chosen because it was easier and safer for the Bulk Beings to keep open and stable there, or maybe that's the only place in the Solar System where the Wormhole could be.
    • Another possibility is that the Bulk Beings actually don't have any control over where the Wormhole appears, and were just lucky enough to have one appear right then and there. Our human protagonists assume that They put the wormhole there, but They could just be taking advantage of a one-in-a-quadrillion event and doing the Bulk-being equivalent of waving their arms and shouting 'Hey, over here!' to humanity.
    • A third possibility (which is easier for us to understand but might require a bit of handwaving) is that wormholes act like other astronomical bodies and need to be anchored to a large body of mass to stay in the Solar system without disturbing the orbits of the other planets. Artificial satellites are able to orbit the Wormhole in the movie, implying that the wormhole produces gravity and thus has some amount of mass. Guargantua could feasibly serve as an anchor point, since it's a massive black hole, and it would have to be this anchor point since there doesn't seem to be any other massive objects in the Gargantua system. The Solar System, on the other hand, has a lot more stuff in it, since the Sun doesn't clean up the space around it as much as a black hole. I'm not sure if the Wormhole would have as much mass as a planet (since it doesn't seem to throw off the orbits of Saturn's moons), but having it orbit Mars might make Mars' orbit unstable. Putting it near Jupiter would be risky because of the amount of radiation that Jupiter creates and it's collection of large moons. Putting it near the Sun might affect the orbits of the inner planets and make manned missions unnecessarily hazardous, so Saturn might have been the best choice.
      • Possibly they could have put it near Jupiter instead, but Jupiter happened to be on the opposite side of the Sun from Earth at the time, making for a more problematic route with a lot of rocket-burst adjustments. Conversely, Mars happened to be in just the right place to permit a trajectory to Saturn that used a slingshot maneuver to save on fuel.
    • The minimum possible delta-v to get to Saturn is 18 km/s, but that would take over twelve years. Newton's first law only applies to objects without an outside force. We have to escape the sun's gravity. We know that the wormhole is not massive enough to disrupt the planets, since it was orbiting Saturn and not the other way around, and Saturn hasn't been disturbing the planets. Given how slowly they move through the portal, it doesn't have a significant amount of gravity even at that distance, and doesn't act any more massive than an asteroid.

     Why visit the planet with heavy time-dilation first? 

  • When they had to decide which of the three planets with promising signals to go to first (they originally had enough fuel to check all three if needed, if I remember correctly) why did they decide to start with the one closest to the black hole? They knew that, even if the mission was successful, they'd have to waste years for this landing and humanity was already running low on time. Wouldn't it be much more logical to check the other two planets first, save the time-warping one for last and only go there if the two other planets turned out to be failures?

    • They couldn't double back because Edmunds was too far away from Miller to travel with the fuel they brought with them, not to mention get back to Earth afterwards. Hence, the desperate plan was taking the chance that Miller was suitable.

    • Romilly mentions shortly after coming through the wormhole that they were "coming up fast" on Miller's planet. If they were already headed in that direction, it would save more fuel to land there first than to head somewhere else and come back later, which plays right into the following "time as a resource" dialogue from Cooper.

    No Miller redshift 
  • Why did Miller's signal experience no redshift from leaving Gargantua's gravity well? Due to the time dilation, there should be a massive difference in the frequency of the signal Miller sends out and the signal NASA receives, presumably to the point of incomprehensibility, but we never hear anything about that.
    • Probably because they could calculate how much redshift there would be and treated the signal appropriately.
    • It redshifts by a factor of over 60,000. I don't think they can pick it up with the same hardware.

    Exact time spent on Miller's planet 
  • Exactly how much time do they spend on Miller's planet? The time slip being about 23 years on Earth places it at just over 3 hours, but after they go over the wave, CASE says it will take "45 minutes to an hour" for the engines to drain, so they can't spend much more than a single hour. Additionally, they leave just as another wave is approaching, which would fit in Kip Thorne's The Science of Interstellar, where he calculates that the waves come every hour or so. And before you mention travel time up/down, the astronauts estimating pre-journey that the entire trip would only take a few years in Earth's frame implies that travel doesn't take that much time anyway. And just to muddy the issue even more, I don't see any "time passes" edit between the waves to imply an hour has passed; Cooper begins draining the engines, he and Amelia have an argument, then Cooper looks out the window to see another wave coming, at which point CASE says it will only take a minute for the engines to drain, but that could just be sloppy editing.
    • Coop has CASE flush all the oxygen out of the cabin into the engine, igniting it to force the water out in one shot. They don't have to wait for the drain, but they have to equip their helmets to breathe.

    Gravity wells and multi-stage rockets 
  • When leaving Earth, a multi-stage rocket is required to put the spacecraft in a low-Earth orbit. From every other planet the astronauts visit, the same craft is quite capable of reaching space on its own, even when that planet has 1.2G. Have I missed something?
    • The (slightly handwaved) explanation would be that the fuel their landing craft uses is very, very precious - which is why they use regular fuel and a standard rocket to leave earth so said special fuel can be saved for when absolutely needed.
    • As good an explanation as we're gonna get, I guess.
    • Already covered above, but basically using a disposable booster to get the Ranger to Earth orbit lets the Ranger save at least enough fuel for one more trip to orbit to use later in exploring other planets. All fuel on space missions is precious.

     No further ships 
  • Ok, I get that it's a post-apocalyptic world and they have limited resources. But still, why the heck doesn't NASA send any further ships after the Endurance? Let's think this through. Once Cooper and Brand return from Miller's planet, 23 years has passed back on earth. In the space of 23 years, you'd expect that NASA would be able to build another ship and send it through the wormhole. And of course they'd want to do that, because the entire human race is at stake, so you might as well put everything you've got into this wormhole idea. But apparently they don't bother, or else they just seriously don't have the resources. (But in the latter case, note that we see Old Brand and Murph at NASA together, and apparently the place is still operating. What is everybody doing there, if they're not building spaceships? They can't all be working on the gravity equation.) But then Cooper and Amelia slingshot around Gargantua, which takes another 51 earth-years. Cooper falls into the black hole and gives Murph the quantum data when she's still 33-ish, and meanwhile Amelia experiences the full 51-year gap in the distant galaxy. During those 51 years, humanity has access to the gravity equation. (Obviously they were capable of putting ships through the wormhole before that equation was complete, but now they're doubly capable.) And they've got 51 years to build ships in! In fact they build a giant cylindrical Ark Ship, complete with a baseball field, during that time. But Murph tells Cooper that Amelia is all alone, and indeed she is alone. How?? In the space of 51 years, with all these advancements, you're telling me they never bothered to build an Endurance 2 to go rescue Amelia? Or heck, forget about Amelia, how about we complete the original mission and survey the available planets to decide where our new homeworld should be? Amelia should have found a whole fleet of ships flying around as soon as she escaped Gargantua's time-dilation field. And at the end of the film Cooper apparently steals a ship so he can go find Amelia. Because apparently they have capable ships just lying around like that, and nobody has ever thought to actually fly one of these things through the wormhole. Even though humanity's future depends on doing just that.
    • Actually is implied in the movie that that is exactly what happen. Cooper finds an entire hangar of ships and takes one to go to Edmunds planet, so they are interstellar ships. Is likely that interstellar travel is common for that time and other colonies in other planets were already made. The people in the Edmunds planet, including Amelia, don't know that due to time dilation.

     Lying about Apollo 
  • How could the lie about the Apollo missions being a hoax possibly be maintained? All it would take is a cursory examination of the video taken and a rudimentary understanding of physics to know this couldn't have been filmed on earth (the hammer and feather experiment done by David Scott during Apollo 15 and any of the footage of the lunar rover kicking up dust comes to mind). Such footage could've only been taken on a celestial body with no atmosphere (i.e. the moon) or in a vacuum chamber far larger than anything that existed at the time (or even today for that matter). And there's far more evidence out there for anyone who cares to look. All this information could not be suppressed.
    • Maybe the intention to suppress curiosity and exploration was so successful that the majority of people either don't care to find out or don't care to listen to those who find out. Who's got time to worry about a conspiracy when you're just trying to find enough to eat?
    • You assume that (a) most of the people in the society depicted even have "a rudimentary understanding of physics" and (b) that they also have easy access to things like footage of the moon landings and the hammer and feather experiment and so forth. In (a), that's something that's a problem even today — there's reportedly a drastic shortage of physics teachers in the US and already large numbers of people that already believe the Moon landing was a hoax, even with the evidence to the contrary easily available. With a repressive and anti-intellectual government actively ensuring that as many people as possible believe this, I imagine this would be even worse. With (b), it is heavily implied that the Internet — and by extension, the easy availability of information we take for granted today — is no longer widely available. It's easy to find evidence to prove the Moon landings when you can call up the relevant footage on YouTube and the page at Rational Wiki at a moment's notice. If you can't, where's the place most people would have any kind of access to this information? School. And who decides what gets taught at many schools? The government. Which brings us back to point (a).
      • The main character is a middle aged guy who holds a engineeer degree and flew for the NASA. The supression of knowledge at most has been going on for a couple of decades, and there are still plenty of people around who must know how things were before. Unless they are also giving some sort of amnesic drug to the population, that kind of information doesn't evaporate that quick.

     How can Edmunds' Planet be Habitable? 
  • Edmunds' Planet is revealed to have breathable air when Brand is shown without her helmet. If the entire planet is much like the location Brand is at (An Earth-like atmosphere with a Mars-like surface, possibly with some bodies of water.), then how can there be Earth-like air without plants and animals everywhere? An oxygen-rich atmosphere is unstable and can only be maintained by life, so it's generally accepted that Edmunds' Planet has primitive life responsible for the oxygen, much like Earth's Precambrian life, but that may not be the only explanation. The planet may have in the relatively recent past (a few to tens of millions of years earlier) supported a rich and diverse biosphere, but a single or multiple severe mass extinction events could have sterilized the world of everything short of single-celled life, thereby making it a clean slate ready for a duplication of Earth life. This would include not just the many Humans Plan B called for, but eventually Cooper and others bringing Earth flora and fauna there. (and this assumes Plan B didn't include an extensive seed bank and various animal embryos.) And what might be the source of the mass extinction(s)? Large flare-ups of Gargantua's accretion disk from consuming Interstellar clouds or the occasional star might do the trick.
    • Or it's just a small desert. We didn't even see a single square mile of the planet. It was pretty rocky, so it would be hard for plants to grow in that exact spot, but that doesn't mean there are none on the entire planet. There's no indication that Edmund's Planet is a Single-Biome Planet by any means.
    • Breathable oxygen can be produced without living things, if there is CO2, light, and enough time, it can split into carbon monoxide and individual oxygen atoms, which can then recombine into breathable O2. The CO2 can get there if there is any natural volcanism on the planet. Depending on how Earthlike the gravity is the oxygen could just have been sitting there for a long time. More simply, it could have been brought to the planet contained in the asteroids that formed the planet.
    • Oxygen can be produced without living things, but not fast enough to matter for a planet's atmosphere. Oxygen is just too reactive, it would leave the atmosphere by reacting with things faster than it could be produced.

     No search for Cooper 
  • If Cooper really was the best Ranger pilot NASA ever had, and none of the other potential pilots had done even a single non-sim flight, why was no effort made to try and find Cooper and convince him to come back?

     New York Yankees 
  • Why is a baseball team as well-known as the New York Yankees playing in a small, local ballpark instead of a huge stadium? I understand the players aren't what they used to be with health deteriorating with less food available, and people are less willing to put money into sports and entertainment (as they find it 'wasteful', alongside technology and space travel), but why are they playing in such a small venue? Even assuming the Yankees are the Away team (which would make sense since the movie's set in Colorado), but the Colorado Rockies also play in a large stadium (assuming they were the Home team in this instance), so why has something as big as Major League Baseball become as small as a little league team? Have baseball stadiums been destroyed/demolished, or are they just an empty wasteland now?
    • With the population so dispersed and land more valuable for crops than roads, a small local ballpark may be all that's needed to house the small number of fans who actually make it to the games anymore.
    • Bear in mind that there is very little interest in anything that isn't food production. The public mindset has shifted to survival to the point that people don't even bother with waging war.
    • Probably a combination of famine and depopulation working to thin out the people who would be making up the crowds and thus the need for large stadiums, food shortages limiting the availability of space for large stadiums (when your food source is suffering from massive blight and you need all the workable land you can find to compensate, devoting a huge space of farmable land for a sports stadium starts to look like a wasteful indulgence), society-wide depression and despair dulling people's enthusiasm for sports and other such things afflicting a failing society. Plus, in this world the New York Yankees are probably a touring bunch of athletes trading on the name; who's to say that they're the 'real' Yankess, or that in this fractured society there's even a New York any more?

     Why no protein-deficiency signs? 
  • If there's no viable food source left for humanity except corn, why isn't the entire cast afflicted with kwashiorkor? Corn, alone, can't provide the tryptophan or lysine needed for complete proteins, hence isn't a sustainable diet.
    • Well, in the film until very recently Corn wasn't the sole source of food, there was also Okra. Nixtamalization is a very simple procedure (that has been known to us for millenia) that helps to make corn more nutritious, and we do have corn genetically engineered to have higher amounts of lysine and tryptophane.

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