science and logic behind interstellar

‘Interstellar’, Explained

Interstellar, Christopher Nolan’s most complicated movie, is not perfect, and neither is it trying to be (as I write in my review here). It uses the science of interstellar travel, relativity, black holes, wormholes and fifth dimension as a tool to tell an emotional father-daughter story.  So, expecting ‘Interstellar’ to be 100% scientifically accurate is not only foolhardy but also, not the right way to watch the film. In fact, many of the theories that ‘Interstellar’ uses, haven’t yet been proved; so it’s virtually impossible to portray them on-screen. Having said that, it doesn’t mean whatever ‘Interstellar’ deals in is all bullshit. In fact, far from it. After all, there’s a method behind all the madness that you see in Interstellar. So, let’s tackle it one by one. Here is the explanation and meaning of science and logic behind Interstellar.

What’s Plan ‘A’ and Plan ‘B’?

Early on in the film, we find out that NASA is working on a plan to have humanity leave the earth in the face of impending catastrophe. The scientists have also learned that an unknown civilization (referred to as “they”, read below) have put created/put a wormhole near Saturn (read about wormholes below). The scientists have also found out after sending a number of expeditions in space that there are three habitable planets in another galaxy. They have named the planets after the explorers who went in search for them: Miller, Mann, Edmunds. And therefore, to understand which out of three planets is actually habitable, they are planning to send a team of scientists (Endurance) to these planets. Meanwhile, professor Brand (Michael Caine) himself has been working to solve a quantum equation for last several years that will solve the riddle of space, time and gravity.

Plan ‘A’ : During the time Endurance will be on its interstellar voyage, Dr. Brand will continue working on the equation, which if solved, will allow them to figure out all the five dimensions including gravity. After which, their plan is to carry all the remaining population of earth in a massive space station to whatever the most habitable planet is.

Plan ‘B’: If Dr. Brand fails to solve the equation, they have a fallback option. NASA have harvested a bank of fertilized embryos which will be carried by the Endurance team on their interstellar voyage, and in case the Earth gets destroyed, they will raise the next generation of humanity in a planet that they find most habitable.

Later in the film, Dr. Brand will reveal that Plan ‘A’ was never possible. To completely solve the equation he would have needed data from the center of black hole, which was impossible to get, and hence the whole plan was a lie.

Warmholes and how do they work?

I think the film does a good job explaining the concept of wormholes in a very short and sweet way. One of the scientists, Romilly, explains it pretty well using a paper and pencil; and it is precisely the concept of wormholes. It is a shortcut in space-time. So, what would take light years to reach in space if followed the normal route, can be reached in a matter of minutes/hours/days through wormholes. Obviously, no wormholes have been discovered yet, but wormholes were always the part of solutions to the Einstein’s field equations for gravity.  Anyway, in the movie, the group of scientists uses the wormhole (which initially scientists think has been put near Saturn by aliens) to reach to another galaxy where the three planets with life potential exist.

Black holes and compressing of time

Black holes are regions of spacetime from which gravity prevents anything, including light, from escaping. Kip Thorne, who also helped Christopher Nolan to come up with black hole models, explains Black holes as: “”When you fall into a black hole, everything that falls in after you over millions of years, as seen by you inside the black hole, comes pounding down on you in a fraction of a second, because of the enormous differences of time flow,”

In short, a place where gravity is excessively strong. So, strong that it even dilates time. The first planet, Miller, that Endurance team visits, has one hour on its surface correspond to seven years on earth. It is because, as mentioned in the film, Miller is located very close to a black hole called Gargantua, and hence time moves much slower on Miller than on Earth.

Who are “they”?

Initially, NASA scientists think “they” to be some extraterrestrial aliens, who are advanced enough to have figured out the five dimensions and hence, can manipulate space and time, and for some unknown reason are also willing to help humans escape the doomed earth. NASA scientists also believe it is “they” who have placed the wormhole close to Saturn so that humans can use that as a shortcut to other habitable planets. It is only in the final act of the film when Cooper (Matthew McConaughey) falls into the black hole to finally find himself in a Tesseract, does he realize that “they” are not aliens but actually future humans. The future humans, who have mastered laws of the universe — space, time and gravity. It is the future humans, too, who constructed the Tesseract for Cooper to communicate with his daughter, and hence, save humans in the past. The implication here is that future humans are trying to save humanity so that they themselves can exist. (I understand, this is slightly ridiculing, since, future humans exist because someone in past was able to survive. It is kind of never ending loop).

Fifth Dimension and the ending

The most “difficult to understand” part of the film is Tesseract or the cubic prism where Cooper finds himself after his spaceship gets destroyed inside the black hole. Basically, it’s a three-dimensional representation of the five-dimensional space. And as already mentioned above, this Tesseract was created by future humans so that Cooper could communicate the data about singularity (center of black hole) to his daughter, Murph (Jessica Chastain), so that she could solve the quantum equation. So, what is fifth dimension, and why is it important to understand? Let’s dive in.

So, as we all know, we live in a three-dimensional space. As per Einstein, and his theory of relativity, time can be considered as the 4th dimension. If you studied maths and graphs, you will remember, that on a two-dimensional graph we represent the two dimensions with axis x and y. Also, to represent space, we must have a third axis z. With the three axes: x, y, z we represent the 3D space. Now, imagine this three-dimensional space across a fourth dimension: time. So, what we are saying is, just like in a 2D graph for a constant x, we can go up and down the values of y; similarly, in a 4D space for a constant x, y and z we can go up and down the 4th dimension, that is time. That’s why and how the theory of relativity supports time-travel.

Now, imagine a 4D space across a fifth dimension where gravity can, too, be controlled. Cooper falls or is rather brought by future humans into this five-dimensional space because:

1st: In a 5D space, he can traverse across time, and
2nd: Since gravity, too, is a variable entity in 5D Space, he can use gravity to communicate to his daughter the quantum data that was needed to solve the equation.

And that’s exactly what Cooper does. He time-travels to his past and uses gravity to move hands of the Murph’s watch to communicate the data to Murph in Morse code. With the data that she gets from her father, Murph is able to solve the equation, which enables humans to master space, time, and gravity. In short, they could now play around with space, time and gravity. That’s why you will see, towards the end of the film, the sort of world that humans have created near Saturn; a world that defies rules of gravity and space.

I hope, I was able to clear most of your doubts about ‘Interstellar’. Believe me, it is not as complicated as you think. I would seriously advise, irrespective of whether you like the film or not, to have a second go at it. I bet, you will appreciate it much more. In the meantime, if have you any further questions or doubts, write them below in comments. I will try to answer them to the best of my knowledge.

Read More: Inception, Explained


  • I have a small doubt, When Copper in 5D, how that robot communicated to him. Where was it at that time. Radio communication is allowed in 5D…

    • They were talking on an extremely advance bluetooth and not radio. Robot TARS was also in the same 5D space but because of the complex nature of the whole creation, Cooper was not able to see him.

  • I would like to know how the endurance could travel over the hot gases around the black hole (just before cooper plunges into the black hole) without getting fried?

    I didn’t understand the part where cooper shakes hand with Brand? I also don’t understand why somebody yelled ‘NO!’ when brand stretched her hand for the ‘first’ handshake?

    • Because, black hole was created by future humans.

      Cooper was time-traveling at that instance. They yelled “No”, because they were not sure what it was.

  • Hi thanks for an amazing clarification. However please help me clarify the last scene in which cooper is seen leaving for planet edmund. So from the station where all the humanity is currently present orbiting the saturn is he going to edmund to get Ms brand back at the station or the edmund planet is the final destination where all the humanity will be eventually moved?(That too why he does that so secretly)

    • This is a genuine question, but from what I interpreted, humans had already formed a colony near Saturn, and I don’t think they were planning to leave to Edmunds. It is only Cooper who went to Edmunds, either to save her, or live with her.

  • How does Cooper Stay alive after the tesseract closes? what happens during that part? how does he reach back in space where he was found by ranger?

  • Why would Dr. Mann, who is supposed to be the greatest scientist to ever grace the earth, do something as stupid as send across false information about the surface of his planet just so he could have someone come rescue him? Didn’t he already know the possible consequences? “Bravest humans to ever live”…

    • This is the only thing I didn’t understand in the movie. Why would Dr. Mann fake those data? Why did he try to kill Cooper? Why was Dr. Mann’s robot programmed for blast? Why? Why? Why?!

  • So Dr.Edmund’s planet is not the final destination for life form you say ? But isn’t tat Jus a Station? Tat place where Murph (old) is shown getting treated ??How could it possibly be able to Sustain large population? And does tat mean he is gonna time travel back to the past ? Like go thru black hole knowing all the consequences?

  • Just wanted to clear something up…in the end it is not a station that defies gravity..its an o’niel cyleinder and it mimics gravity using centrifugal force.

    • Probably. But Plan ‘A’, itself, rested on solving the equation; without which humanity won’t have been to fly or live in the space-station.

  • Why did they choose a solar system with a black hole in it ? Wouldn’t that be a bad and short term decision for humans? And did the worm hole lead only to this system with 3 possible planets or does it also lead to the other 9 that the lazarous missions talked about

  • you said in the end murph created a station which defies time space and gravity ,where they are carrying last remaining population .how defies time space and gravity can you explain this.a boy with baseball hits the ball up in the air that scene

  • That’s really well written and apt article. Thank you. I just had one doubt. How can one use/change gravity to move hands of a clock? Gravity is a force towards the center of a planet. So how did he move the hand forward and backward? That means he had the power to exert force in each and every direction. Why didn’t he used this power to maybe pick up a pen by applying upward force on it and then writing somewhere. Would have been easier.

    • Do you think for a person who just came to know that he can control gravity can pick up a pen and write ? It’s as if you asking a person who has just learnt to drive car to compete in F1.

    • According to Einstein’s general relativity gravity is not restricted to define it as a force towards the center of an massive object
      but it asserts as a force that results from warping of space time geometry. Massive object warps the space time geometry so we experience the force defined by us as gravity. Einstein generalizes the concept of gravity in this way. So, if we can warp space time geometry in any possible way we can generate gravity. The film is probably depicting this particular idea of Einstein.

  • But how can cooper control the seconds hand in murph’s watch by use of gravity ? i mean he can’t move it with the help of gravity as it acts vertically ??

    • According to general relativity of Einstein gravity is the 5th dimension of space and time. This means gravity is dependant on space and time and vice versa. All the four dimensions of space, time and gravity are interrelated in such a way that if anyone of these quantities changes for an observer than remaining others quantities will change for that observer in a way so that speed of light remains the same for that observer before and after the changes. This is the essence of Einstein’s relativity. So, if gravity can be controlled by some mean than other dimensions including time will change (i.e. from past to present or vice versa) for that observer to maintain the speed of light. Or in other words ticking of clock will be faster or slower according to the change. Ticking of clock slower or faster doesn’t mean speeding or slowing the mechanical ticking by using any force vertically or so. But slowing or speeding the time itself. Control of ticking of clock is always a common and may be a easier example or instance to present this idea in the film or any where. So, this simply mean to say or depict this extraordinary idea only.

  • As per grandfather paradox, we are unable to time travel in the past. How come Cooper travels back in time?
    Next is, yes I understand when you travel with a speed of light you can travel to future. But how come by controlling gravity how can you access any point of time future or past?
    Further, we know no object can survive in a black hole so when Dr Mann explains about survival instinct, is watching Murph is past is the survival instinct of Cooper? And he is actually dead?

    • 1.I didn’t understand what you said about the grandfather paradox ( can you tell me what you tried to say? )
      2.Gravity affects the speed of an object, many a times its not in a direct way but it still does for example when you are going up a hill you go a lot slower than when you come down. So if you create a gravitational field much much greater to what we have on Earth and go towards it with maximum power there are chances that you might reach or even pass the speed of light depending on you “maximum power” and the gravity field.
      3.We do not know whether an object gets destroyed or stays intact in a black hole cause nothing ever came back. And i guess this is how the “future humans” setup the tessaract in the black hole for Cooper to enter.

    • 1- He didn’t actually travel to the past, he was using the gravity to communicate in the morse code, he wasn’t actually present in the daughter’s bedroom ,that’s why her daughter referred of having a ‘Ghost’ in her bedroom, cause she can’t see her just communicate
      2- Gravity and time are interdependent and connected, That’s why near a black hole 1 hour was equal to 7 years on earth because The gravity near the black hole is so high that the fabric of time is stretched to counter-act that on an insane level
      3- ‘They’ as in future humans, have mastered the 5 dimensions and can easily manipulate it as they like, just like we can do with 3-D plane

    • Hey man it was the Tesseract in the Blackhole built by the future gen. of human to show cooper’s daughter through cooper about singularity and saving earth from extinction. He actually went into the Tesseract not only in the black hole

  • Hi, first of all let me just tell you across the entire movie blogger network. Your explanation of “Interstellar” is just mind blowing and the best till date. You have explained everything in detail with the most simplest way anybody can. So a big “KUDOS”.

    Having said that you missed on a crucial aspect of the movie in this post which is about “Them”.

    Many people are still in argument as to hows its possible that if Cooper landed in the Tesseract that it was built by future humans, since the very existence of the wormhole or the artificial black hole is not possible unless the human race survives.

    So basically what Christopher Nolan missed out explaining in the end in a more simpler way is that this whole plot was based on a parallel universe where initially Plan B was successful, and there is no other alternative to that. The advance human race were able to solve Dr. Brand equation in some time and that’s how they helped this version of Humans to survive. Whats your take on this?

    • Thanks.

      What you are saying is one of the many interpretations. There’s a reason Nolan didn’t explain everything. He wanted to leave it open ended so that we can discuss just the way we are doing now.

    • that’s why he mentioned that it seems like a never ending loop..because cooper had to go in the future, convey the data to his daughter and help her solve the equation.. so that past human race survives..its as if like our ancestors who died way back come in our dream and guide us what to do.. here its just like we ourselves coming in the dreams to save us…

    • Time distortion- Think of time as a stream… we are now going with the flow… But when you divert slightly from it , the stream tries to bring you back into it. Well as the stream is less continuous now it causes distortions (changes in original form). Well the actual time taken for the protagonists to reach the “habitat-able planets” would take an unimaginable time.But by going through the worm hole they reached the planets in a matter of minutes/hours thus diverting from the time stream, So to fix this the time flowing out of the wormhole flowed quicker than the time flowing in the wormhole. ( I hope you understood this, BTW its my iteration of what might have happened ).

    • Its a very basic medium of communication where letters are translated into dots and dashes Example: D in morse is ” _ . .” (dash,dot,dot). This type of communication was created during War times during 1800’s when communicating in war zones was too hard

  • Well Great Explanation there Man!! *Claps*. Unfortunately i still have a few doubts…
    1.When Cooper returns back to Earth, it seems like the whole planet became a halo/donut instead of being a sphere.Why is that?
    2.How did solving the equation for gravity help getting rid of the dust storm, the storm that killed almost every single crop and half the life on the planet?

  • If the “future humans” knew that Cooper had to tell Murph the solution to the equation why put him through such work? Like why did he and his crew had to go to those other planets (where they could have easily died seeing what happened) Couldn’t they have come directly to Murph or Dr.Brandt and tell them the solution Dr.Brandt could have atleast died peacfully!!!

    • Quotes from the movie: 1. “We’re here to communicate with the three-dimensional world! We’re the bridge!”
      2. “They have access, to infinite time and space, but they’re not *bound* by anything! They can’t find a specific place *in* time, they can’t communicate. That’s why I’m here. I’m gonna find a way to tell Murph, just like I found this moment.”
      3.”My connection with Murph, it is quantifiable. It’s the key!”

      Sorry to say, but You gotta re-watch the movie.

  • How does murph still get to read the morse coded watch after Coop leaves the tesseract and she’s taken the watch out of her room (apparently to her office/NASA) ??

    • Anish, your question is logical, but the movie’s timeline is not in a linear pattern. The editing is not done to show You different shots happening at the same time. For example the concluding part, where Anna Hathway’s character has just reached Edmund’s planet, is not happening while Cooper is talking to her daughter in the hospital. This does not necessarily means all the movie is in non-linear timeline. All these years watching Mr.Nolan’s work, You gotta apprehend such details.

  • Good explanation. It’s just the last part you are wrong. With the quantum data murph gets they simply get knowledge about gravity, they dont master space-time. The messed up world we see at the end is nothing but a bigass space ship(like NASA’s command centre) shaped in a centrifugal form(which is required to generate gravity in space, and a proven concept). Similar forms of spaceships are used in Martian and upcoming movie The passenger.

    And 4th dimensions isnt called Time, its ‘Space-Time’.

    To understand the movie I would recommend people to watch the Science behind interstellar, which is produced by the makers of interstellar. Available on YouTube.

  • Nice and convincing explanation. However I have a question. Cooper found NASA address through gravity, which he himself has created from tessaract. Without getting that he cannot go to the mission. So the very first time when he is still in earth and not there in tesseract, how he find the address of NASA. Because unless he finds it, he cannot exist in tesseract.

  • My doubt is that, Cooper comes back from future and gives his daughter the calculations so that they can leave earth and go to a safer planet, but she recieves a message “STAY”. That means Cooper has to to stay and shouldn’t go. Then if he doesn’t go, how can the further things happen???

  • Hey man whoever you are you don,t know much about science or the facts used in the movie which was latest science and research pictured and put beautifully in the movie, it was not all b****it or fiction but all of the latest findings and all science.From time running slower near blackhole to wormhole bending time and space and gravity being the only thing to travel backward in time all were latest research and findings of science bought together by Christopher Nolan. It was not Star Wars where every planet supports life and you could roam anywhere or every planet has same mass bcz it didn’t affect anyone from planet to planet. They had limited fuel and resources how Cooper communicated with his daughter with gravity was truly amazing.. So stop commenting on the Oscar Winning movie bcz. you are just too small worth for criticizing such great movie….

    Please do reply on my comment….

  • […] ‘Interstellar’ is not perfect, and neither is it trying to be. It uses the science of interstellar travel, relativity, blackholes, wormholes and fifth dimension as a tool to tell an emotional father-daughter story.  So, expecting ‘Interstellar’ to be 100% scientifically accurate is not only foolhardy, but also, not the right way to watch the film. In fact, many of the theories that ‘Interstellar’ uses, haven’t yet been proved; so it’s virtually impossible to portray them on-screen. Having said that, it doesn’t mean whatever ‘Interstellar’ deals in is all bullshit. In fact, far from it. After all, there’s method behind all the madness that you see in Interstellar. You just need a little patience and multiple viewings to completely get the film. Read: Full Explanation […]