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Mechanical Energy - Self energy of Universe

  1. Jul 21, 2013 #1
    What is the total mechanical energy (self energy) of the universe that is due to the fact that it expands, taken the big bang as the origin - on the basis of general relativity?

    If anyone could supply me with the equation and number (what size is it in kgm2/s2) I would be very thankful.
  2. jcsd
  3. Jul 21, 2013 #2


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    There is no meaningful way to express the expansion of space as a kinetic object of objects inside.

    Unrelated to that, the total size of the universe is unknown (it could even be infinite). You can ask for the observable universe.
  4. Jul 21, 2013 #3
    Thx, that is what I had thought was the standart view, but someone whom I thought would know for sure made me believe differently .... that was why I asked this question. All good. Thx.
    Last edited: Jul 22, 2013
  5. Jul 22, 2013 #4
    What can I ask for the observable universe? Considering there is no meaningful way to express the expansion as a kinetic object.
    The observable universe is what I'm after. So is there any energy associated with its expansion or not? - Because I was told there is just the way I did it is wrong...

    Thx in advance
    Last edited: Jul 22, 2013
  6. Jul 22, 2013 #5


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    The average energy density (for regular matter, dark matter and dark energy) is an interesting number.

    The cosmic energy inventory

    You can associate the acceleration of the expansion with an energy density (dark energy). You do not have to, however.
  7. Jul 22, 2013 #6
    You will notice in the article MFB posted there is a kinetic energy value, however that energy describes a different process than those associated with expansion see section 2.10
  8. Jul 22, 2013 #7
    Thank you both, and thank you very much for the paper. Will have a good read. The acceleration -DE context sounds exactly what I stumbeled accross.
  9. Jul 23, 2013 #8


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    Energy is not defined in GR on global scales.
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