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B Standard Ruler

  1. Jan 27, 2017 #1
    What I'm doing wrong?
    speed X time = distance
    0,6 c X 380000 jr = 228000 ly
    times expansion of 1000 gives 228.000.000 ly
    This is equal to about 72 Mpc
    Why is the standard ruler 2 times as long: about 150 Mpc
    What is wrong, or do I forget in my calculation?
     
  2. jcsd
  3. Jan 27, 2017 #2

    mfb

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    2016 Award

    Staff: Mentor

    What exactly do you want to calculate? Where do those numbers come from?

    A (!) standard ruler is any object of known size.
     
  4. Jan 27, 2017 #3
    With these numbers I am pointing of course at the cosmic standard ruler which is used in the BAO.
    Speed fundamental tone of acoustic waves 0,6 c, time to sound horizon 380.000 yrs
    And the calculated standard ruler is the radius of the sound horizon shell (not the diamater)
    So, again, why 2 times so long?
     
  5. Jan 27, 2017 #4

    Bandersnatch

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  6. Jan 27, 2017 #5
    Thank you very much. By coincidence I was just beginning to think into that direction when your answer arrived.
     
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