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Current value of the scale factor(R₀)?

  1. Dec 20, 2011 #1
    What is the current value of the scale factor(R₀)?

    a= R(t)/R₀

    Give me the number.
     
  2. jcsd
  3. Dec 20, 2011 #2

    Simon Bridge

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    R0 is the value of R(t) at t=0.
    Apart from that, need more information.
     
  4. Dec 20, 2011 #3

    e.bar.goum

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    Since a = R(t)/R0, and we normalise to the current epoch, right now, R(t) = R0
     
  5. Dec 20, 2011 #4

    Simon Bridge

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    <headslap> cosmology forum!
     
  6. Dec 20, 2011 #5

    e.bar.goum

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    Sorry, is that directed at me?
     
  7. Dec 20, 2011 #6

    Simon Bridge

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    No - I don't slap anyone elses head unless there is some sort of contractual obligation.
    See post #2 ... mumble mumble I suppose had I shut up people would think I was being clever?
     
  8. Dec 21, 2011 #7
    Number?????????
     
  9. Dec 21, 2011 #8

    e.bar.goum

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    It's a scaling factor, there isn't one. Maybe if you be more specific with your problem, we can help you. You can arbitrarily change it depending on your cosmology.
     
  10. Dec 21, 2011 #9

    George Jones

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    If the universe is not (spatially) flat, then

    [tex]R_0 = \frac{c}{H_0} \sqrt{\frac{k}{\Omega_{m,0} + \Omega_{r,0} + \Omega_{\Lambda,0} - 1}}.[/tex]
    If the universe is (spatially) flat, then [itex]R_0[/itex] is arbitrary.
     
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