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Homework Help: Calculating the scale factor (cosmology) for a universe starting at the Big Bang

  1. Nov 25, 2012 #1
    1. The problem statement, all variables and given/known data

    Show that by using the Friedmann-equation you can determine the scale factor for a Universe in it's early stages (starting with the Big Bang) to:


    2. Relevant equations

    The equation for the scale factor:


    Where r(t) is the distance from us to a given galaxy to the time t and r0 is the galaxies current distance from us.

    And the Friedmann equation:


    3. The attempt at a solution

    I'm dumbfounded and I have no idea of what to do. This is for a major paper and any help is much appreciated. If you don't understand the problem, please do say so and I'll try and clear it up. Thanks a lot!
    Last edited: Nov 25, 2012
  2. jcsd
  3. Nov 25, 2012 #2
    Here is my thinking so far: isolate the scale factor so that you have:


    and then find values for the two unknowns somehow.
  4. Nov 25, 2012 #3
    Doesn't matter anymore, figured it out. You can lock this now.
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