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Homework Help: FRW Equation

  1. Mar 3, 2012 #1


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    1. The problem statement, all variables and given/known data

    Metric: ds^2 = -c^2 dt^2 + (t/t*) (dx^2 + dy^2 + dz^2)

    (I guess t* is a constant?)

    Is this universe matter dominant? Explain

    2. Relevant equations

    3. The attempt at a solution

    I guess you have to use the FRW equation?

    Assuming the usual FRW form, we set a^2 = t/t*

    to find H^2 depends on 1/a^4. This means it's radiation dominant, right?

  2. jcsd
  3. Mar 3, 2012 #2
    If H^2 depends on 1/a^4 then yes, this is radiation dominant since matter is a^-3 dependent. I didn't check the work though.
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