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Traveling near c

  1. Apr 18, 2003 #1
    Ok, so I'm sitting in class thinking, which is never a good idea, about objects moving near c. I think that if you have a wire moving near c and shoot an electrical signal down it, the signal is going to move faster than c, but then I remember Lorentz and that contraction will fix that, but then what if you hurdle a non-ionized hydrogen atom near c. What happens the the electron and or its orbit. You could use a Lorentz contraction to change the path length, but how far can you stretch a nucleus before it breaks down, or could you have the orbit simply run perpendicular to the nucleus direction, and if this is the case, what happens to atoms with more electrons, or molecules.
  2. jcsd
  3. Apr 18, 2003 #2
    Well, here are some things to think about.
    In the frame of refference of the atom itself (or actually the center of mass of the object which this atom is made of, just to take the idea of temprature breaking atoms away), the atom is not streched at all, therefor it is not even on the limit of breaking :smile:

    And, about the signal in the wire, I think the signal's speed is measured from the frame of refference in which it was made, not from the frame of refference of the conductor.
  4. Apr 18, 2003 #3


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    You must remember that velocity must be measured with respect to something. With that in mind let us measure the earths velocity with respect to the distant galaxys. In that frame of reference the earth is moving at a significant fraction of c. Now do your experiments, what do you observe?

    The point?

    No matter what your velocity (that is, what point you choose to reference your moition to), you will not observe any effects of relativity in YOUR frame of reference. c will remain c, the velocity of the electrons in atomic shells or your TV will be the same.
  5. Apr 18, 2003 #4
    ok so say the wire is travelling @ 1 m/s less than the electrons travelling through it and the wire is one meter long and has zero resistance.
    How long will it take for the electrons in the wire to go form one end to the other?
    Im guessing 1 second.

    Answers on a post card. :smile:
  6. Apr 18, 2003 #5


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    The time required for a electron to move through a wire is not as easily determined as you would have it. In reality a single electon moves very slowly, the energy transfer due to an electric current is more vibrational then translational.

    Further electrons are firmly bound to the atomic structure of the wire, so basicly all electrons in a wire have the same velocity as wire. If a stationary observer were able to measure the velocity of an electron of a current carrying wire as it moved past the net velocity of the electron would be determined by the Lorentz transforms.
  7. Apr 18, 2003 #6


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    How slow is very slow?
  8. Apr 18, 2003 #7
    Depends on the material and conditions, but on the order of 1 mm/sec is common IIRC.
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