On Friday, December 2, 2022 at 4:53:22 AM UTC-6 [email protected] wrote: > The definition of the Hubble Constant implies the rate of expansion slows > as time advances. I don't see that the two values contradict this > conclusion. AG > > The FLRW expansion factor is exp(Hd/c), where Taylor's theorem means exp(Hd/c) = 1 + Hd/c + 1/2(Hd/c)^2 + ... . For small distance d we have exp(Hd/c) =~ 1 + Hd/c, and for Hd = v this is exp(Hd/c) =~ 1 + v/c. To convert this to a time dependent expansion then d = ct.
LC > On Friday, December 2, 2022 at 3:24:35 AM UTC-7 Lawrence Crowell wrote: > >> Red shift data from supernovae SN1 give H = 74km/sec-Mpc. The velocity of >> a region at distance d is v = Hd. Using the CMB data H = 70km/sec-Mpc. The >> two data points appears distinct at a rather high sigma. >> >> LC >> >> On Friday, December 2, 2022 at 3:15:15 AM UTC-6 [email protected] >> wrote: >> >>> It's measured about 70 km/sec/megaparsec. This is a direct measurement >>> using red shift to measure recessional velocity, and different standard >>> candles depending on the distance. So, at a distance of one megaparsec, the >>> expansion rate is 70 km/sec; at two megaparsecs the expansion rate is 140 >>> km/sec; and so on. This suggests the rate of expansion is greater as we go >>> back in time; or conversely, that the rate of expansion is slower as we go >>> forward in time. How is this reconciled with the 1998 measurements that the >>> rate of expansion is actually speeding up? AG >> >> -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/5b731200-4929-4ae2-8b03-21e3da54fbbbn%40googlegroups.com.
