ArpitGarg's Weblog

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Interstellar: Time Travel Climax explained

with 13 comments

Saw Interstellar last night; another one of the notebook movies. I call them notebook movies as you have to sit with a notebook and pen to understand the mind-bending concepts.

I liked the movie overall which has a repeat value for me on the entertainment quotient alone. First half is a bit lazy as it unfolds, but second half is an edge of a seat journey.

This movie is based on scientific nuances of Time Travel, Wormholes, Black holes, which humans know in theory but are yet to corroborate by experiencing physically. It contains directors take on such concepts. In the process it fringes on the boundaries of present scientific knowledge. Hence explanation of entire movie within the layman notion of science might not be entirely possible. However I will relate what I make of it. This post deals with the Time Travel Climax of the movie and the confusion thereof.

Let me call Two Coopers as Cooper farmer (who lives with child Murph) and Cooper bookcase (who went into the blackhole and emerged into the bookcase). Cooper bookcase gave Cooper farmer the coordinates to the NASA facility. Cooper farmer could not have gone to NASA and eventually become Cooper bookcase without knowing these coordinates. How did Cooper (any one of the two) come to know the coordinates in the first place? Someone other than Cooper would have told them right? How does the knowledge of coordinates become self sustaining? Cooper told Cooper, but who told Cooper?

This deals with the concept beyond what humans have experienced physically. The 4th dimension of Time. Post Miller mishap, a desperate Cooper asks Amelia, “Can’t we go back to past, change something to save people?” And Amelia replies, “Time flows in one direction. We can’t change what has already happened”. Her reply was perfect as far as our 3D world goes. But when Time becomes a dimension, we can travel though time too.

Just like we travel in 1D (ants moving in a single line), 2D (cockroach crawling the floor), 3D (insect flying in the room), we can travel through time in 4D (where 4th dimension is Time). In 1D, we can move back and forth on the line; in 2D we can crawl in any direction on the floor and in 3D we can fly in any direction in space. Similarly we can move in any direction in time.

Here comes the catch. Since we have understanding of just 3D world, we start asking questions about, “What will happen if someone goes in the past and kills his grandfather, thereby erasing his own birth?”, Or in the movie’s case, “The Cooper farmer got the coordinates from Cooper bookcase and went to NASA and ultimately reached the bookcase from where he relayed back the coordinates. How?”

Various scientists have tried to explain the Grandfather paradox from the 3D understanding,

  • “A new timeline will emerge when he kills his Grandfather, a parallel universe”, Or
  • “We can’t change anything. What will happen, has already happened. The rules of dimension make sure of it”.

Since we have never experienced the 4th Dimension of time, whatever science of today tells are mere guesses. Researched Guesses to be exact. But still guesses.

As I see in 3D, we can move from one 2D plane to another 2D plane, which would be mind-bending to a person who lives in 2D. Similarly in 4D, we can move through time, front and back. In fact past-present-future all exist simultaneously (don’t think of them as existing at the same time. Time has become a dimension now, not just a measure of past-present-future). The concept of PPP is no more in 4D. Hence Cooper bookcase and Cooper farmer can come to know of coordinate from each other as they both exist simultaneously in 4D.

Since time is not uni-directional in 4D, to think that Cooper bookcase came to know of coordinates only coz he was Cooper farmer in the past is wrong. It’s not Past-Preset-Future but Future-Past-Preset, Present-Future-Past anything. The only fact is that both Coopers has to come to know of the coordinates somehow. Information in 4D does not flow from Father to Son, but can be Son to Father too. In either direction.

Bookcase Cooper does not depend on existence of Farmer Cooper as time is not longer linear (Amelia was hence wrong). Bookcase Cooper came to realize this in Tesseract where he saw the entire timeline of the Murphs room all at once. Initially he tries to stop Cooper farmer by asking Murph to make him STAY. But he realizes it’s futile as laws of 4th Dimension are not allowing it.

What Nolan has portrayed is a 4th Dimension with a closed loop explanation, which says nothing can change. Cooper bookcase can tell anything to Cooper farmer; still he will end up in the bookcase. When he says “Stay”, Cooper farmer ignores the message, whereas he easily believes in Gravitational anomaly message from Cooper bookcase. Rules of universe made sure of it.

Similar is the explanation as to how future humans survived in the first place to be able to put wormhole to attempt saving past humans.

If and When humans conquer the 4D, they may find this explanation to be entirely wrong. Something we have never thought of could be the reality in 4D. Till then we are free to throw off our own hunches and punches just like Nolan has done.


Written by arpitgarg

November 10, 2014 at 6:54 pm

13 Responses

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  1. Thax..awsm explanation..


    November 3, 2015 at 11:12 pm

  2. Hello Arpit,

    I have a simple doubt. I guess you might be able to clear it.
    As you said, If it was the Cooper Bookcase who was sending those signals
    ( both NASA coordinate details and STAY message);
    What does he actually want? STAY or GO

    If he wants the Cooper Farmer to “STAY”, then why is he also sending the coordinate details of NASA?
    If he really wanted Cooper Farmer to STAY, the easiest way was to not send the details about NASA.
    And if he wanted Cooper Farmer to GO with the mission, why does he send a message to STAY?

    Paul Varghese

    November 20, 2014 at 11:16 pm

    • Hi Paul,

      Inside the bookcase, Cooper saw the entire timeline of that room together.

      1. He find himself through the singularity into the bookcase. He felt confused/scared. He thought he will never see his daughter again. So in panic he tried to send in STAY signal. Bookcase Cooper sent STAY signal to TIME of farmer Cooper when farmer Cooper had decided do go on mission (means by that time he had already received the coordinates and been to NASA). Bookcase Cooper understands that STAY signal had no effect on Farmer Cooper, as he decided to GO even after getting STAY signal.

      2. Above understanding gave idea to Bookcase Cooper that whatever he do, he can’t change his coming to Bookcase. Moreover he now understood that he himself was the force that gave coordinates to Farmer Cooper in the first place. So now he selects that very TIME from Bookcase timeline, and sends the coordinates. This he did to close the loop. His not having done so, Bookcase Cooper might have emerged in the 5th Dimension (supposedly parallel timelines). So to keep himself inside his timeline, he closed the loop of information.

      3. If Bookcase Cooper had not given coordinates to Farmer Cooper, a new dimension might have opened. Past would have been changed and hence the future. Bookcase Cooper might not have been able to go back to his own timeline and meet his daughter.


      November 21, 2014 at 2:17 am

      • Why was he struck in the bookcase?? Why can’t he go to some other place in the 4D world?? And how can he move books and whisper, if he can’t give the complete details??


        November 22, 2014 at 12:45 pm

        • The directors view on this seems to be 5D beings rendered the 3D view of the 5D world for Cooper to grasp. It was the view from behind the bookcase across the timeline.

          He can communicate only via manipulating gravity (a force which movie says transcends dimensions)

          He does not move books. He manipulates gravity.


          January 1, 2015 at 3:22 am

    • Its not something that cooper confused or scared. He thought if he makes himself stay in the earth he can save the world by getting the singularity equation message through the bookself. But the future people (they invented the 4th dimension ) never meant for him. they meant for his daughter. so that his 4th dimension filled with his daughter room. so initially he thought to make him stay…then he understood it was meant for her daughter so he embedded the morse code on the watch

      Mohamed asaraf

      December 8, 2014 at 3:22 pm

  3. Good stuff from Nolan, but hard to sleep knowing these plot holes:


    November 19, 2014 at 9:01 pm

    • Hi Arpit ,

      Your explanation is awesome .. Though the climax , I found to be very confound but after getting your inputs while going through the blog … I felt satiated and relieved.
      Just a small query..
      Does this apply in our world also ?
      I feel future is always defined …People say that we cant predict the future.
      I feel Its an end goal , Its a conclusion of your whole life anecdote. Present and Past moments try to manipulate the different avenues and moments which come in our life to reach to the end goal that is Future. Here we call it some Supernatural power or Destiny. Future is always defined.
      Is it the basic premise of the movie too? Cooper was far ahead of the time .. He knew where he was ..
      That was the end goal .. To reach to that goal . He manipulated the past and present with some hi-fi concepts of Physics .

      Please share your thoughts



      November 26, 2014 at 12:38 pm

      • Your view seems appropriate.
        Its not that future is defined.

        Once we transcend to 4th Dimension. Past-Present-Future is not linear but exist at the same time.

        Like infinite 2D planes exist together to create a 3D world.

        In that sense future is defined. But we shud not see future as something that stems from past.
        Past can viewed as something that comes by rewinding from the future.

        There are other hypothesis also on this topic. One of them is very amusing. It stems from Newtons Law. Since a system does not change in absence of external force. And b4 big bang there was a singularity. Big bang happened spontaneously w/o any external force. And it expanded. Galaxy’s got created. Earth and humans etc got created. Then the contraction started (Universe is in contraction phase right now) ultimately leading to the singularity back.

        Again big bang and since no external force, so same universe, earth, humans will get created. So in the sense we have lived our lives infinite times already. Hence future has already been lived infinite times and hence defined already.


        January 1, 2015 at 3:31 am

        • that was dope:-)



          September 8, 2017 at 8:22 pm

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