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Rotational reference frames

  1. Feb 8, 2008 #1
    It occurred to me that, as far as calculating the position or movement of objects a reference frame can be rotational, see the "http://en.wikipedia.org/wiki/Rotating_reference_frame" [Broken]. So instead of seeing the Earth as orbiting the sun you could say that the Earth is stationary and the rest of the universe is rotating around an axis going through the sun and perpendictular to the plane of the Earth's orbit. (I feel dizzy…)

    Of course, this results in all sorts of "http://en.wikipedia.org/wiki/Fictitious_force" [Broken]. It also seems notable to me that this will also mean that non-rotating objects a certain distance from the axis will appear to be moving faster than c. And accelerating at a ridiculous rate, of course.

    I was wondering if anything interesting is derived from the fact that any object can be construed as rotating at any rate by selecting a different rotational reference frame. And also if anything interesting happens as the speed of rotation approaches the speed of light with respect to a non-rotating reference frame. (Not physically possible with any known material, of course, but you get what I mean.)

    It seems that this relativity of rotation can't be "real" in that there's only one reference frame where conservation of momentum, conservation of energy, etc. aren't violated. (Or is there a Lorentz-transformation-like way of correcting for that?) So does that mean that even though the universe doesn't have a "here" and a "there" (i.e. no absolute inertial reference frame) it does have an "up" and a "down", left and right, forwards and backwards? (Obviously these are anthropomorphic labels but the point is that cardinal directions are the same somehow everywhere and everywhen and in every inertial reference frame.)
    Last edited by a moderator: Apr 23, 2017 at 10:40 AM
  2. jcsd
  3. Feb 8, 2008 #2

    D H

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    In talking about orbits you have the wrong concept in mind for a rotating reference frame. The motion that occurs when one body orbiting another body is not rotation; its an orbit. A rotating body is spinning about some axis located within the body. The reason the surface of the Earth is called a rotating reference frame is because the Earth is rotating about its own axis (which is why our days are only 24 hours long).
  4. Feb 8, 2008 #3
    Uh, thanks. But the reference frame that an orbiting body would be stationary in would still be a rotational one - I'm talking about a reference frame rotating, not an object - and the various questions above still apply.
  5. Feb 8, 2008 #4
    Maybe what confused you is that the phantom forces in the situation I describe aren't things like centrifugal force but are things like the Corolis force, with other objects in the universe accelerating along curved paths. Look at the animation on the right in "http://en.wikipedia.org/wiki/Coriolis_force" [Broken].
    Last edited by a moderator: Apr 23, 2017 at 10:40 AM
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