If you say boo to a goose and it flies away, rather than attacking you as they used to at York University, then the sounds you hear coming from it will shift to a lower frequency as the waves from your point of view are spread out. This is the Doppler effect and applies to light waves as well. As we know, Edwin Hubble noticed that the light from distant galaxies was red shifted, that is, the wavelength of the light we received from them was longer, implying that the galaxies were moving away from us and that the further ones were moving away faster than the closer ones. This was taken to mean that all the galaxies were moving away from a common centre as if there had been a Big Bang (or a Big Boo) 13.6 billion years in the past.
Looking at local galaxies, the Hubble expansion rate has been measured to be 73 km/s/Mpc. That is, galaxies one megaparsec (Mpc) away from us are apparently moving away from us at 73 km/s.
Recently, a new method was devised to calculate the Hubble constant from observations of the Cosmic Microwave Background, that represents the cosmos long ago at a redshift of Z=1000, and then extrapolating forward using standard models assuming dark matter and dark energy. Perhaps not surprisingly they got a different answer: 67.7 km/s/Mpc.
This discrepancy is now much bigger than the uncertainties in these two numbers, so it is significant (Reiss et al., 2019). As is usual in physics now, to avoid offending anyone, this is called "The Hubble Tension", but in fact it is a falsification of the present model (as stated, the difference is larger than the error bars).
What does QI have to say about this? Well, there is an interesting link up. If you look at the difference in these speeds you get 73 - 67.7 = 5.3 km/s/MPc. Scaling this up to the speed at the edge of the cosmos you get 155,000 km/s and if you calculate an acceleration from this by dividing by the age of the universe you get
Acceleration = 3.8x10^-10 m/s^2
This is the mutual acceleration of both sides of the cosmos and we just want that of one, so when we divide by two we get about 2x10^-10 m/s^2. Those who know about quantised inertia, QI (surely most of you reading by now) will see immediately that this is the minimum cosmic acceleration predicted by QI as 2c^2/CosmicScale = 2x10^-10 m/s^2. So maybe the Hubble "Tension" is just the fact that they left QI out of their model!
Note that there is probably more to this, as I'm not sure I believe in the physical acceleration model either, but you must admit this does all fit rather well!
References
Riess, A. et al., 2019. Large Magellanic Cloud Cepheid Standards Provide a 1% Foundation for the Determination of the Hubble Constant and Stronger Evidence for Physics beyond ΛCDM. The Astrophysical Journal, Volume 876, Issue 1, article id. 85, 13 pp.
