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Is existence faster than the speed of light?

  1. Nov 6, 2005 #1
    lets say theoretically you have a rope 200,000 miles long and it was pulled tighted with a person on each end one persons pulls the rope towards them instantaneously the rope begins to leave the other person wouldnt this conclude that something is faster than the speed of light?
     
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  3. Nov 6, 2005 #2

    ZapperZ

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    Instantaneously? How do you think the force moves along the rope? What do you think holds the molecules of the rope together?

    Zz.
     
  4. Nov 6, 2005 #3

    cepheid

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    I would argue that your premise is flawed. Does it happen instantaneously? Not likely. Would if it the rope were a perfectly rigid body? Maybe. Do perfectly rigid bodies exist? No. There is some elasticity in the rope, and even if it is very small, think about it on an atomic scale. You pull on the rope. All contact forces are electrostatic. The atoms have to influence their neighbouring atoms, all the way down the line, to the other end. There is a definite propagation time associated with that. That's my take on it. Does anyone disagree, or have I stated anything that is incorrect?

    Note also that a rope cannot be pulled perfectly taut, it will sag under its own weight. That doesn't relate much to your question, I just thought I'd point it out.

    Edit: ZapperZ beat me to it in a much more succinct way, but I feel more confident now that he has hinted at the same thing I said.
     
  5. Nov 6, 2005 #4

    Integral

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    By the way, if you replace your rope with a steel rod the results are the same. Any effort to move the rod, moves through the rod at the speed of sound in the rod. If you apply forces great enough to create a signal which moves faster then the speed of sound in the metal you will deform the rod.
     
  6. Nov 6, 2005 #5

    cepheid

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    Interesting! That suggests to me that the speed of sound in a solid material is tied to the natural frequency of oscillation of the atoms in the crystal lattice. Try to exceed that frequency, and you destroy the lattice, at least in one place. Am I right?

    Edit: Or does it have to do more with the maximum allowed amplitude of said vibrations? :confused:

    Edit2: Sorry for getting all excited like as if it was some sort of revelation, but the idea that acoustic signals are just mechanical vibrations, even when NOT in air (right?) was sort of there in the back of my mind, but brought out vividly by this example.
     
    Last edited: Nov 6, 2005
  7. Nov 6, 2005 #6

    Integral

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    I am on thin ice here... Yeah, hitting the rod harder would induce larger amplitude sound waves. My thought was that if the impact strikes the rod at a velocity greater then the speed of sound in the rod the rod will be deformed. (Depending of course on the material which hits the rod!)

    The true experts in this would be Gukul, I will yield to a post from him.
     
  8. Nov 7, 2005 #7
    ok let me clarify the rope was pulled tight and then sat down the person pulling is the only one hplding the rope now lets say we did this on a smaller scale even with a steel pole the pole being pulled away would be noticed almost instantly so whats to say that this extremely long pole doesnt react the same and if im coming off as an idiot im sorry im actually very new to the whole physics scene im teaching myself physics in a high school in an independant studies class and this is practically my project learning from the experienced
     
  9. Nov 7, 2005 #8

    Doc Al

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    Just like with the taut rope, the "pull" is transmitted along the steel pole at the speed of sound in steel. For short lengths, it may seem to travel instantly, but it doesn't. (Nowhere close to the speed of light!)
     
  10. Nov 7, 2005 #9
    Just think of the types of forces interacting which cause it to move

    *hint* the atoms don't touch each other
    :)
     
  11. Nov 7, 2005 #10
    You can imagine the analogy of a traffic jam in a highway; a car moves a little bumps into the next in front of it then that car begins to move and bumps into the next then...............
     
  12. Nov 7, 2005 #11

    -Job-

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    I guess what you're asking is equivalent to saying, "suppose i have a row of dominos 200,000 miles long. If i knock the first one over, then this will be noticeable at the other end instantly, hence something is faster than light."
    It's not really the case because it takes time for the last domino standing on the other end to fall. Similarly with any rope, you're basically setting off a chain of dominos where the dominos are the molecules in the rope. So you can see it can't be instantaneous, even if at a small scale it seems that way.
    If the rope were a rigid body, then the scenario would change to a row of dominos where the dominos are packed together (rather than being at a certain distance). In this case, if you want to make the last domino fall, you have to hit it hard enough so that the perturbation at one end reaches the other end with enough strength to knock down the last domino. Notice that this perturbation loses some of its strength with each domino it goes through because the dominos offer some resistance and push back in the other direction. For a 200,000 mile such chain you'd need considerable energy. Most likely, even if you hit it with enough energy, instead of making the last domino fall, the dominos in between will probably jump out of place to the side, so the perturbation never reaches the other end with enough strength. This is equivalent to the rope breaking. A better strategy would be to hit the first domino multiple times with less strength, so that you have a better chance to disturb the last domino. Of course this isn't instantaneous.
    I would say if the rope were perfectly streched (maximum stretch), and you pushed it on one end, it would break. This is actually evident in the assumption that the rope is perfectly stretched. When we say that the rope is perfectly stretched we are saying that rope is streched as much as possible without having it break. Hence stretching it a bit more must cause it to break.
     
  13. Nov 7, 2005 #12
    another thing to add is that you could think of the passangers as the atoms and the cars could be the repulsive magnetic force of the electrons; so the atoms themselves do not touch but the magnetic field "kinda" do.
     
  14. Nov 7, 2005 #13

    -Job-

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    This brings up a curious scenario. If i had a rope about a light year in length with one end hanging 6 feet from the ground, even though it is not attached to anything or being pulled by any force at the other end, i would easily be able to climb up on it a good deal. :smile:

    (even if it was considerably shorter than a light year, we can probably estimate how long such a rope would need to be in order to allow me to hang from it a certain amount of time)
     
    Last edited: Nov 7, 2005
  15. Nov 7, 2005 #14
    It seems to me that the initial question "is existence faster than the speed of light?" has been overlooked by the the initial writer and subsequent responses.

    Whilst the question, can anything travel faster than the speed of light? has been answered and has made for interesting reading, the question is existence faster than the speed of light is another concept altogether.

    Existence is relevant to the observer and the interactions that the internal and external stimuli effect upon the brain. I am aware of things existing around me, but only as they have occured in the past (the question of what existence means if nothing exists to observe it is a philosophical one). However, what of the awareness of my own existence?

    One could argue that existence itself must travel at the speed of light based on the electrical interactions within the brain. But what if the signals are being created by the subconscious before the actions begin? Even at the atomic level, existence must precede an action. If this is the situation, then could it be possible for thoughts to be created before they are thought? If so, then what are the implications for organic computers (if we go down that path) and artificial intelligence?
     
  16. Nov 7, 2005 #15

    Integral

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    Unfortunately this is the physics forum, here we must talk of physics. I do not see any evidence of physics in your response.
     
  17. Nov 7, 2005 #16
    possibly, however I was attempting to answer the question, nothing more. The beauty of physics is that it refers to all interactions of matter and energy. Philosophy is still an important part of the processes of our understanding the universe, if you want lengthy mathematical desciptions based on these ideas (all they are) they can be provided but id prefer to save that for my job and enjoy the general discussion. Thinking outside the boundaries of mathematical equations keeps my mind active and alert.
     
  18. Nov 7, 2005 #17
    (Nothing) is faster than the speed of light, To pun a fact, It's everywhere in the Universe.
     
  19. Nov 8, 2005 #18
    agreed, but does everything obey our current understanding of the laws of physics? until we discover a successful Theory of Everything, things that cant be directly observed such as the complexity and of existence must still be dealt with carefully. I find it very difficult to imagine anything being able to cheat its way around the boundaries of c, however, we know so little of the interactions of matter, particularly at plancks length. Do not all the laws of physics break down within a singularity? what happens then at planks length when the proposed extra dimensions come into play?
     
  20. Nov 8, 2005 #19

    Not only should there be a successful theory of (EVERYTHING) but there should also be a successful theory of (NOTHING)
     
  21. Nov 8, 2005 #20
    the forces propagate though the material at <c, I have heard some claim that it is at the speed of sound (in that material) but I dont know and Im not willing to do an experiment
     
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