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The opposite of the limit of light

  1. Sep 1, 2010 #1
    I was thinking about the theory of relativity and how the faster we go the slower time goes and the smaller we become which evens out the equation for speed.

    Distance / Time = speed

    Correct me if im wrong but what i see from this is, as we go faster time slows down and distance decreases which keeps the speed of light at a constant to the person in motion. So 1 second in the equation becomes, .9 seconds as we go faster. And as we get up to the speed of light, time becomes 0 and the distance is 0 in the equation. So using this cant we go the other way, and go slower to the point that 1 second is longer and our distance is larger? Maybe even calculate what a truely stationary object would be?
  2. jcsd
  3. Sep 1, 2010 #2


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    No because the time dilation factor (gamma) is dependent on the absolute value of the velocity in our (inertial) frame. It doesn't matter which direction the clocks we are observing are travelling we will still observe them to run slow.
  4. Sep 1, 2010 #3
    So our clock will always be the fastest? everything else that we observe will be slower? Wouldnt that make us stationary?
  5. Sep 1, 2010 #4


    Staff: Mentor

    In our frame, yes, by definition.
  6. Sep 2, 2010 #5
    So if we are always the slowest moving object from our own frame, wouldnt that mean the speed limit of light only applys to other objects? because no matter how fast we are moving we are always at 0 in comparison to the speed of light.
  7. Sep 2, 2010 #6


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    Yes. What? Yes.

    How does the middle statement, follow from the first and last statements? (inasmuch as a preceding statement can follow a following statement, if you get my meaning...)

    Do you mean why can't we travel at the speed of light?

    Well, even if we were travelling at .99999999999999999c, we'd still be stationary in our own frame, so it's not like our being stationary in our own frame is preventing us from travelling at c.

    Remember, we can only measure our speed wrt other objects. The trick really is to get our frame moving away from some other frame, such that that other frame is moving away from us at the speed of light. And that we can't do.
  8. Sep 2, 2010 #7
    That just blows my mind.

    Im having trouble putting this and the energy of movement together now. If we arent moving, no matter how much thrust we put into trying to move us, where does that energy go?
  9. Sep 2, 2010 #8


    Staff: Mentor

    In our reference frame, yes. Of course the speed of light limit applies to us in other reference frames.
  10. Sep 2, 2010 #9


    Staff: Mentor

    In this case your frame is not an inertial frame so things like energy conservation require a bit more care. However, essentially the energy goes into the kinetic energy of the exhaust gasses.
  11. Sep 2, 2010 #10


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    If you are using thrust to accelerate, then in any given inertial frame, your speed is changing. Of course if your speed is changing in every inertial frame, then the definition of which frame qualifies as your "inertial rest frame" is changing over time.
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