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Can someone please explain this aspect of Interstellar

  1. Apr 14, 2015 #1
    I know there are many aspects of Interstellar that are true to science and it appears that there are many that aren't. I was confused about one particular aspect but wanted to know if this was actual science or one of the things that wasn't.

    Ok, so Earth sent some scouts to 12 or 13 possible planets. Over a period of 10 years, Earth had been getting a ping from the water planet (the one with the giant tidal waves). I don't believe they give the frequency of the ping but for arguments sake, let's say Earth gets the ping once a month. That's 120 pings over 10 years. When Cooper's ship lands on the water planet, they say the scout on that planet died minutes before they landed. This was explained because of the time dilation (1 hour to 7 years on Earth) and thus the craft must have had about 1.5 hours on the planet. However, in order for Earth to have received 120 pings, that must mean that the scout craft sent 120 pings right? So was the frequency of the pings from the scout craft was 120 over 1.5 hours. This frequency would have been what they setup initially from Earth.

    Is my thinking correct? If not, can someone please explain this in more layman terms?

    TIA
     
  2. jcsd
  3. Apr 14, 2015 #2
    The frequency of the "ping" which is received on Earth will be less than the frequency at which it was emitted on the planet. This effect is called gravitational redshift. It basically means that as light moves against the strong gravitational force of the nearby black hole (and of the planet as well but to a very small degree) towards the "wormhole", it's frequency reduces. Light which moves from a region of lower gravitational potential to a region of higher gravitational potential always gets redshifted.
     
  4. Apr 14, 2015 #3
    Ah ok, it's as I thought. Thanks for the clarification.
     
  5. Apr 14, 2015 #4

    Hepth

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    What about all of the GPS-enabled tractors going/returning to the guys house? Did they cut a scene where he programs them? GPS doesn't work by gravitational pull, and if it was by compass why would they all return to a pole?
    As a moviegoer it really bothered me.
     
  6. Apr 14, 2015 #5

    phinds

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    The GPS has to take gravity into account, else yours in your car would have you driving into buildings and fields instead of on the road. According to my notes (and I can't give you the math to back this up but the figures come from a thread on this forum:

    So most of the accuracy depends on the assumption that the Earth's gravity field doesn't change from what was programmed into the GPS system)
     
  7. Apr 14, 2015 #6

    Hepth

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    Yeah, I know general relativity. But why did they go to his house, from all other fields? And not just have some small error about their location and thus move incorrectly.
     
  8. Apr 14, 2015 #7

    phinds

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    Artistic license, and general BS would be my guess.
     
  9. Apr 16, 2015 #8
    I would assume there was a deleted scene that explained this. Perhaps he used it as a test bench to figure out exactly how to manipulate stuff while in the black hole?
    But again thats all supposition
     
  10. Apr 28, 2015 #9
    My guess, the tractors recognized that something was wrong with the GPS and so switched to a backup program.
     
  11. Apr 29, 2015 #10

    Hepth

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    I guess my complaint was that they were pretty good about explaining all of the goings-on of the movie, except this one aspect. Even though it doesn't matter to the story it makes it feel sloppy. If there had been a sentence where he said "They all switched to backup mode for some reason when they lost GPS", then nobody would have asked this question. Instead we're left to wonder what magical science caused it to happen, as most of the other scientific stuff was at least based in reality (for a little while rather).
     
  12. May 9, 2015 #11
    My biggest problem with the movie Interstellar was the worm hole. A worm hole is two black holes that are connected. Black holes have a mass that exceeds 3 solar masses. Yet they place one of these black holes right next to the planet Saturn without any apparent gravitational effects. If you placed a 3+ solar mass object anywhere near our solar system, you would definitely notice gravitational effects. Placing a worm hole next to the planet Saturn should have disrupted the entire solar system. That completely ruined the movie for me and made the rest of the movie unwatchable.
     
  13. May 14, 2015 #12
    I believe the worm hole in the movie is traversable worm hole rather that the Schwarzschild wormhole you may be referring to. The Schwarzschild wormhole came out of the solutions to Einstein's Equations of general relativity but I think they evaporate so soon as to not allow anything to cross it. The traversable wormhole shown in Interstellar is very accurate to the theory in my opinion. Of course Kip thorne himself who first demonstrated their possibility was science advisor to the film.
     
  14. May 14, 2015 #13
    There is only one type of "worm hole." It is known as the Einstein-Rosen Bridge (sorry, but Kip Thorne was not the first to demonstrate their possibility). Albert Einstein and Nathan Rosen created this solution in 1935 in an attempt to eliminate singularities where mathematical quantities become infinite. Worm holes are not stable structures. According to the theory, a worm hole opens and closes too quickly for even a photon to get through. Although some have suggested that exotic energy might keep the worm hole connection open longer, it remains unclear whether that is even physically possible. In either case, there is no escaping the fact that at least 3+ solar masses are required, at either end, in order to form a worm hole.
     
  15. May 14, 2015 #14
    I cant discuss with you further with you if you are going to be illogical. To make definite statements (which are also false) about these hypothetical features of nature is unscientific. Wormholes are allowable solutions to the equations of general relativity, there are multiple solutions that take the form of what could be called a wormhole. You misunderstood I clearly wrote that Kip Thorne was the first to demonstrate the possibility of Traversable wormholes in this paper here http://authors.library.caltech.edu/9262/1/MORprl88.pdf. You are also wrong about Einstein and Rosen discovering the 'Einstein–Rosen bridge' it was discovered by Ludwighttp://en.wikipedia.org/w/index.php?title=Ludwig_Flamm&action=edit&redlink=1 [Broken]Flamm in 1916 way before Einstein and Rosen. Apparently they found it independently and I wouldn't question Einsteins integrity but It seems unlikely they never saw his paper. Anyway im not well versed in wormholes but I do check my thoughts against probable fact and experiment before I write. I think you should do the same, if you wish to follow the scientific method. A quick check of wikipedia is not as rigorous as checking your text book or a published paper but its getting close in my opinion and of course its easy. A quick check will set your facts straight. Heres an excerpt I just found "The Einstein–Rosen bridge was discovered by http://en.wikipedia.org/w/index.php?title=Ludwig_Flamm&action=edit&redlink=1 [Broken][14] in 1916 a few months after Schwarzschild published his solution, and was rediscovered (although it is hard to imagine that Einstein had not seen Flamm's paper when it came out) by Albert Einstein and his colleagueNathan Rosen, who published their result in 1935." Knowledge is power, providing its correct.
     
    Last edited by a moderator: May 7, 2017
  16. May 14, 2015 #15

    DaveC426913

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    Really? I found they left a lot for the audience to interpolate. Which I kind of appreciated.

    I'm not sure why you didn't make this leap. Well ... you did make this leap.

    This is a film that definitely does not spoonfeed its audience. We are still talking about it months later. That is the hallmark of a good film.

    So we have an excellent explanation as to what happened, we just had to get there on our own because it didn't pander to an unintelligent audience. Why does this dissatisfy you?
     
  17. May 15, 2015 #16

    Hepth

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    Because then THIS explanation is the only one that seems non-"deus ex machina" and based on default science. It felt like everything else that was extraordinary was just inter-dimensional ghost dad's fault. Even so, the GPS-default reason not a good one because if the GPS system were WRONG; as if it were getting weird timing measurements due to some gravitational anomaly that made its precision poor, the machine would not know where it was with accuracy. Therefor it could not return to the farm with accuracy, (and we saw that all of them lined up in a way that didn't seem to be some default configuration, but a face-the-front-door-of-the-house configuration.) The chances of that feel low.
     
  18. May 15, 2015 #17

    DaveC426913

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    hrm... The whole part about whether their GPS was directly thrown akilter, such that they literally got lost is, in my view, drastically overthinking it.

    It was a ten second plot point. The machines simply got confused by some aberrant signals and their program was to go home. That's all the story needs to cover. And cover it, it did.

    Anything else is us inventing our own rationale, and then finding it wanting. There was no mention of any GPS faulting in the story - that's been invented here in this thread.

    Think about a fictional Google car. If it gets anomalous readings in the fuel injection, that does not mean "I'm not getting any fuel and therefore I have halted in my tracks"; it means, "hey something's definitely not right, I'd better limp home for servicing before really bad things happen." If a self-driving car did that, we would not question it further, or wonder how exactly it could have gotten home with a fault in the fuel. It did.
     
  19. May 18, 2015 #18
    I watched that movie twice, lots of the science seem possible. I don't quiet understand your question though, and even confuse why the water is so shallow on that planet yet the tidal wave could be so huge. beside, a spaceship could withstand gravitational force, yet cannot withstand tidal waves?

    the ending of the movie is even more confusing to me.
     
  20. May 20, 2015 #19
    I don't think the water was shallow. In order for the entire planet to be covered in water either the water must be very deep or the surface must be extraordinarily flat. When they stepped out of the ship, I assumed they had landed on the top of the previous ship. The tidal forces from a close black hole would be really intense and I'm sure could easily produce waves that big, especially with no land to slow them down and with less surface gravity than Earth.
     
  21. May 21, 2015 #20

    DaveC426913

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    Here's the problem with that:

    Tides in deep, open water don't have steep waves. In fact, they are so gradual, you would need instruments just to tell that you are rising and falling. (After all, crest-to-crest distance = the planet's perimeter/2.) See diagram below. OK, that's for Earth Moon, but the tides are the same.

    Where you get tall, short waves is in shallow water, where base of the wave is retarded by the seafloor, allowing the crest to overtake it.

    hilotide.gif
     
    Last edited: May 21, 2015
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