# Thread: Riess and Plancks Hubble constant values

1. Established Member
Join Date
Nov 2005
Posts
533

## 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.

2. Order of Kilopi
Join Date
Aug 2008
Location
Wellington, New Zealand
Posts
3,945
Originally Posted by john hunter
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. Closed pending moderator discussion.

Update:

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

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•