We see Murph finally realised that Cooper is her ghost. Cooper has transmitted the quantum data encoded via manipulating the gravitational waves affecting the watch's seconds hand on Murph's bookshelf. However, the subsequent scene shows that Murph is decoding the watch signal in her NASA office. How?


2 Answers 2


It seems to be a function of the tesseract. From Ch. 30 of The Science of Interstellar:

By the time Cooper has received the quantum data form TARS, he has mastered this means of communication. In the movie we see him pushing with his fingers on the world tube of the watch's second hand. His pushes produce a backwards-in-time gravitational force, which makes the second-hand twitch in a Morse-encoded pattern that carries the quantum data. The tesseract stores the twitching pattern in the bulk so it repeats over and over again. When forty-year-old Murph returns to her bedroom three decades later, she finds the second hand still twitching, repeating over and over again the encoded quantum data that Cooper has struggled so hard to send her.

(The "bulk" is the higher spatial dimension that exists between the Tesseract's 3D "sides")

  • 1
    The question is asking about when Murph takes the watch from the room, and is still able to view the message being sent in Morse.
    – phantom42
    Nov 24, 2014 at 16:59
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    @phantom42 - Yes, I know. If the tesseract can store the pattern and continually send it to the clock at different points in time, why should it have any special problem if the clock leaves the room? Is there any suggestion that its gravitational signals can't escape the boundaries of the room?
    – Hypnosifl
    Nov 24, 2014 at 17:05
  • Unknown, but if so, it does sort of raise the question of why Coop didn't try to send the message to Murph more directly instead of on a watch that she had left in the room for all those years.
    – phantom42
    Nov 24, 2014 at 17:08
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    @phantom42 - I would speculate it's because of the "interface" of the tesseract--he has to be able to actually see an object (specifically its 4D world-tubes) in order to tell the tesseract he wants to send a pattern of gravitational waves to it by banging on the world-tubes. And he didn't seem to have conscious control over where the tesseract took him, maybe it was picking up on subconscious wishes.
    – Hypnosifl
    Nov 24, 2014 at 17:30
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    @phantom42 Cooper is a 3D being, and the Tessaract needed to provide him with a simple point of reference to position on Earth where Murph was likely to be found throughout her life. Having anything larger than a room would be impractical. So he can only affect the things inside the room. However, the Tessaract and the higher beings behind it are not bound by such petty limitations
    – Petersaber
    Jun 23, 2015 at 10:38

Maybe we are thinking too three-dimensionally. It's theorized that some of the higher spacial dimensions are really "small" (though infinite) and curled up and exist within every point of our three-dimensional space. Do not ask me to explain this.

So, maybe the tesseract sends gravity through some of the higher dimensions which are curled up within each point inside the watch, such that removing the watch from the room really doesn't matter because the higher dimensions travel with the watch.

I know "they" are supposed to be fifth dimensional beings, but that doesn't mean the tesseract doesn't operate through higher dimensions.

  • There are a bunch of extra space dimensions in string theory, but there are theories of large extra dimensions which suppose that one of these dimensions is not curled up at the same tiny Planck-scale size as the others, and this large extra dimension is often referred to as the "bulk" dimension. Kip Thorne makes clear in ch. 23 of The Science of Interstellar that he is assuming there is one such large extra dimension.
    – Hypnosifl
    Nov 27, 2014 at 0:08
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    Specifically, he says "Physicists who struggle to understand quantum gravity think this is the fate of all the extra dimensions except possibly one or two: they are curled up on microscopic scales ... In Interstellar, Christopher Nolan ignores these curled-up dimensions and focuses on just one bulk dimension that's not curled up."
    – Hypnosifl
    Nov 27, 2014 at 0:10
  • Wow, that is fascinating Hypnosifl. Just to clarify: do you mean that the the universe of Interstellar only assumes three-dimensional space plus time plus the bulk, to the exclusion of any curled up higher dimensions? If so, then my answer about curled up dimensions obviously would be wrong within that universe.
    – Xplodotron
    Nov 28, 2014 at 15:30
  • @Xpodotron - I interpreted it to mean that the curled up dimensions just weren't relevant to the narrative, not that they didn't exist at all. Since they'd be curled up at the Planck scale, intelligent higher-dimensional beings wouldn't perceive them or have freedom of movement in them, and from what I understand of real theories of "large extra dimensions", only the non-curled dimensions would be relevant to macro-scale deviations from the expected behavior of the gravitational force (for example, it might obey an inverse-cube rather than inverse-square law at millimeter scales).
    – Hypnosifl
    Nov 28, 2014 at 18:00
  • And for more on real theories of large extra dimensions, you can read this article or the wiki page, and The Science of Interstellar discusses these models too. For a good extended discussion there's the book Warped Passages by Lisa Randall, one of the physicists behind the Randall-Sundrum model, apparently one of the most popular models of large extra dimensions because it doesn't require much fine-tuning.
    – Hypnosifl
    Nov 28, 2014 at 18:06

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