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Is vacuum acceleration directly proportional to distance?

  1. Aug 17, 2015 #1
    Do we know if the instantaneous/observed acceleration due to the vacuum is directly proportional to distance or possibly? (ignore any gravitational effects)
    A~D ?
    A~D^2 ?
    A~D^(1/2) ?
    A~D^(-2)
    A~D^(Other) ?
    OR
    A= constant (edited as I forgot this one)

    If not, is there a best guess/fit or simply not precise enough data?

    Feel free to correct my question if it is simply a bad question. I didn't see this directly address in any thread; if I missed one, a link would be great.
     
    Last edited: Aug 17, 2015
  2. jcsd
  3. Aug 17, 2015 #2

    PeterDonis

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    What do you mean by this?
     
  4. Aug 17, 2015 #3
    The observed acceleration of distant objects from the supernova data or other observation.
     
  5. Aug 17, 2015 #4

    marcus

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    You could look at the Hypersine thread.

    To an excellent approximation, distances are growing and are expected to continue growing as the function
    sinh2/3(1.5 t) where the present is at time t = 0.8

    This looks more and more like exponential growth (at a very low rate of about 1/173 % per million years) as time goes on. Eventually it will be indistinguishable from exponential growth at that rate call it H

    D(t) = eHt

    If you differentiate that you get the expansion speed is proportional to the distance multiplied by H and if you take the derivative again you get the acceleration is proportional to the distance multiplied by the square of H

    The Hypersine thread https://www.physicsforums.com/threads/the-hypersine-cosmic-model.819954/#post-5146660
    has some graphs that show the distance growth curve and the gradual onset of exponential growth at a small constant rate.
     
    Last edited: Aug 17, 2015
  6. Aug 18, 2015 #5
    The Hypersine thread provided the understanding of the acceleration rate I was looking for.
    Thanks!
     
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