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Thread: Riess and Plancks Hubble constant values

  1. #1
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    Riess and Plancks Hubble constant values

    Just an update for anyone interested…

    Continuing from this https://forum.cosmoquest.org/showthr...how&highlight=

    In a previous post https://forum.cosmoquest.org/showthr...pc)&highlight= it was argued that the rate of expansion of the universe is half of Hubbles constant i.e a(dot)/a is approximately 36km/s/Mpc

    It was argued that this was due to a misunderstanding of the redshift-scalefactor relation which should really be 1+z = [a(0)/a(1)]^2
    Which in turn led to a luminosity distance dL=(2c/H(0))*(1+z)sqrt[(1+z)-1] and an apparent omega(m) of exactly 0.25 from CMB, and just under 1/3 from supernovae

    ... this graph https://www.desmos.com/calculator/njz3vohptp (Betoule data) shows that the above equation, matches supernovae data well, with constant H(0), i.e. q(0)=-1 (constant). The top orange curve is the above equation, the middle green one is LCDM with omega(m)=0.3089 and the bottom is CDM with omega(m)=1

    Consistency can be found from Riess and Planck data as follows…

    1) Planck https://arxiv.org/abs/1502.01589 uses BAO data to determine H(0)
    section 5.2 formula (25), has the expression cz/H, in which the z should be 2[sqrt(1+z)-1]
    A z of 0.57 is used, so BAO might overestimate distances by a factor 1.126 (0.57 compared to 0.505993) and hence underestimate Hubbles constant by the same factor.
    Plancks value of 67.3km/s/Mpc, formula (27), times by 1.126 becomes 75.8 km/s/Mpc.

    2) With omega(m) as 0.25 and using the latest Planck value for omega(m)h^2 of 0.142 gives H(0) = 75.4km/s/Mpc

    3) Riess 2016 https://arxiv.org/abs/1604.01424 has H(0) of 73.24, but in the analysis uses q(0)=-0.55 derived (as mentioned near the bottom of page 15) from his 2007 paper, which uses the assumption of the faulty LCDM model. The q(0) should be -1.
    When this value is applied to equation (5) it changes ax and so from equation (4) changes H(0), by a factor 10^ax. The data has redshift between 0.023 and 0.15, with more data near the 0.15 side, figure 8 page 47. The change at different redshifts is: for z=0.023 it's by a factor 1.0052, z=0.05 it’s 1.01115, z=0.1 it's 1.0235, z=0.15 it's 1.036 so a factor 1.025 is applied. 73.24*1.025 = 75.1km/s/Mpc

    1-3) are consistent with each other given the errors involved and have an average value of about 75.4km/s/Mpc
    Last edited by john hunter; 2018-Jan-07 at 11:12 PM.
    "...when you have eliminated the impossible, whatever remains, however improbable, must be the truth." Sherlock Holmes

  2. #2
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    Quote Originally Posted by john hunter View Post
    Just an update for anyone interested…
    As you know from your other ATM thread on the same subject:
    The physically measured value of Hubble's constant - H(0) - is over 70 km/s/Mpc.
    The value of a(dot)/a is called the Hubble parameter H(t) and varies with time.

  3. #3
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    Closed pending moderator discussion.

    Update:

    This thread will remain closed because it continues discussion of an ATM topic that has been previously closed...twice.
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