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Amount of dark Energy at different times

  1. Dec 17, 2015 #1
    I am wondering what the formula would be for the amount of Dark Energy in the observable universe would be for different time (t). (according to best current theory/data)

    Would it be this directly proportional to volume?
    Dark energy (t) = Dark energy (present time)/ (scale factor (t)3)

    If so, 6GY ago scale factor = 1.618 therefore Dark Energy would be about 1/4 the current amount.

    I could be way off as I am just starting on this stuff.
    Last edited: Dec 17, 2015
  2. jcsd
  3. Dec 17, 2015 #2


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    I don't think that the amount of dark energy is a useful quantity (total energy is not well-defined in General Relativity). The density, however, is useful, and can be thought of as a constant (if it does change over time, those changes haven't yet been detected).
  4. Dec 17, 2015 #3


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    Apart from what Chalnoth said about the usefulness of total energy, the radius of the observable universe does not scale directly with scale factor a. You mentioned a=1.618, which is in the future, so I guess you intended to say a=0.618, which correlates with 6 Gy ago.
    The radius of the observable universe was then about half of what it is today ( D_particle ~ 23 Gly then, according to LightCone 7) and the total vacuum energy in the observable universe about one eighth of today (at constant density).
  5. Dec 18, 2015 #4
    Jorrie: That clarifies what I was looking to understand. I also was not using scale factor term correctly.
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