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Self-rotating body with speed of light

  1. Jun 1, 2010 #1

    I am not a physics guy but I got this idea, sorry if this is a dumb question.

    What happens if a self-rotating solid cone that accelerates to speed of light in space. Imagine that it has a circular base and at the apex there is only one atom.

    What happens to it, it it going to get disintegrated when it reaches the speed of light? Is conical base is going to be effected first or the apex of one atom?
  2. jcsd
  3. Jun 1, 2010 #2
    Do you mean that you have a body that rotates and then you take a bystander who moves really close to C compared to this rotating body and imagines how he would see it?
    What would happen is that according to a bystander it would now rotate slower due to time dilation.
  4. Jun 1, 2010 #3


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    First of all there are no truly rigid objects in relativity. If you rotate anything very fast it has no choice but to distort into a different shape. The apex wouldn't be affected, but the stretching or squashing would get worse further away.

    Secondly, even if you had a sufficiently flexible elastic cone that wouldn't shatter into pieces, there isn't enough energy in the Universe to spin the cone fast enough to reach the speed of light.

    EDIT: I assumed above that you were referring to the rotational speed reaching the speed of light, not that the cone was rotating slower but moving sideways as well. But there's still not enough energy for anything to reach the speed of light.
    Last edited: Jun 1, 2010
  5. Jun 1, 2010 #4
    Very true, the mechanical work to accomplish such a feat is infinite.
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