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Space and single objects.

  1. Feb 5, 2009 #1
    A funny thing I have been thinking about and probably a lot of other people.
    How would I do to send an instant message to anywhere like, for instance, to a distance as far as the moon from earth.
    Easy, only by using an object that covers the distance :p A long wooden stick that I would point toward the moon and knock on it. All I need is a long tree in which get the wood and big muscles to wield it lol.
    As I've just copied it from somewhere on the internet "under certain circumstances subatomic particles such as electrons are able to instantaneously communicate with each other regardless of the distance separating them" Why wouldn't they be the same object same thing as the wooden stick.
    The distance to cover and the space to cover are two different things. Withing a same object there is no space to cover and if my friend on the moon grab my stick and pull it down I would feel it instantaneously. Well the article I have taken it from is about the holographic universe theory which I advise those who don't know about it to read :) In this theory they say that these particles would be the same object, or rather, different display of the same broadcast particle.
  2. jcsd
  3. Feb 5, 2009 #2
    rigid rod FTL communication

    Forget what you read "somewhere on the internet" about instantaneous, and now imagine if your long stick was really, really, floppy (like it was made out of rubber hose). You could shake one end, but the other end wouldn't move instantaneously, in fact you could watch the movement go like a wave across to the other end.

    But you're thinking of a rod that is as straight and stiff as an arrow? I guess you've never seen http://www.youtube.com/watch?v=SuHW8InB5tk"! That's right, compared to the speed of light, nothing is rigid.. and that's why you can't send an instant message from Sydney to Tehran.
    Last edited by a moderator: Apr 24, 2017
  4. Feb 5, 2009 #3
    If you take a pencil and move it from left to right like from that [..__.......] to that [.......__..], won't both the ends of the pen move in the same time ? That's my point, no matter the length of the pencil and no matter its speed or acceleration but if there was people at both the ends of it, they would have the pencil slip off their hands before they even see the other end moving wouldn't they, because nothing can travel faster than light but light has to travel anyway. The pencil doesn't, both its ends just go a very short distance to compare with the distance the light has to cover. I may be wrong in which case I am sorry
  5. Feb 5, 2009 #4
    This won't work. When you move your end of the pencil you're really moving the atoms of which the pencil is composed. The ones closest to your finger move first, then photons from them move the other atoms further away, and then they move atoms further away, ... until eventually the other end of the your pencil moves. So the other end of your pencil does NOT move instantaneously and is in fact bounded by the speed of the photons that move it. It may look instantaneous to you, but if you were to see it in slow motion you'd see that the process is slower than just shining a beam of light from one end of your pencil to the other. Both processes are facilitated by photons, but moving the pencil takes longer.
  6. Feb 5, 2009 #5
    Look at Einsteins famous very large rotating wheel where the outer perimeter should move faster than light - but of course cannot, so the whole thing bends.
  7. Feb 5, 2009 #6


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    No need to over-complicate the issue with Einstein's wheel.

    All objects made of atoms are not rigid. The hardest material - even in theory - will still only transmit movement down its length at a sublight speed. In fact, significantly slower: it will transmit movement down its length merely at the speed of sound in that material.

    The speed of sound through steel (from here: http://hyperphysics.phy-astr.gsu.edu/Hbase/sound/souspe2.html#c3) is about 6.4km/s. Waving rod made of steel that stretches from Earth to Moon will take about 16 hours to get there.

    Diamond, the hardest substance known, will have a delay of a little less than 8 hours.
  8. Feb 5, 2009 #7
    wow men :smile: thanks for the detailed answer I can really see how wrong I was. Non object can transmit the motion faster than the speed of light indeed.
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