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Inflation/ unification

  1. Feb 23, 2012 #1
    In GR gravity is seen as a property of space-time , curvature. Now we know that sometime after the plank's time we had the universe dominated by radiation ( recombination) as such the rate of inflation was in the range of ~ 10^30 m/s , which as you can see is considerably larger than the VOL ( at about 10^-37 to 10^-35 of a second).

    I might be waffling here but if the expansion of the universe itself is not constant due to various parameter , however , the way I see things it has no affect on individual photon speeds.On the other hand I am not sure how gravity field ( or quantum graviton would behave).
    I find this in conflict with what GR proposes where gravity doesn't stay constant , and acts as a function of the mass's object.

    Can someone shed light over this.

    Is this one of the reasons why we are finding it hard to unify GR with E-M ?

    P.S: I have more questions in mind which I will ask following on to replies.

  2. jcsd
  3. Feb 23, 2012 #2


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    Where are you getting your numbers (e.g. 10^30 m/s)? This is not the way that expansion rates are reported. Also, "inflation" refers to a specific epoch during which the early universe underwent accelerated expansion. What is "VOL"?

    That's right. It doesn't and shouldn't.

    You're losing me here. Gravitational fields are described by GR in terms of geometry. The universe is described by a non-static (expanding) spacetime, and GR accommodates this description perfectly fine. Where is the conflict?
  4. Feb 24, 2012 #3


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    As an aside, there is no problem whatsoever unifying gravity with electricity and magnetism. The problem is unifying gravity with quantum mechanics.
  5. Feb 24, 2012 #4
    I presumed that since heavier masses have more warped space-time curvature , then as a consequence of this the G-field/ wave itself would have a varying propagation speed (sound nonsense to me) , but now that I think of it , a field's strength is proportional to the number of flux lines ( as is the case with B-fields , so perhaps same thing applies to gravity ? )
    I don't know how I came with such a vague assumption. Obviously there are various parameters involved at different epochs.

    Thanks for the correction (@ Chalnoth) .Of course it's the unification of gravity with QM that is being an issue.
    Last edited: Feb 24, 2012
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