The wiki page on the Hubble parameter also says in the section at https://en.wikipedia.org/wiki/Hubble%27s_law#Time-dependence_of_Hubble_parameter that the expansion seems to be accelerating in such a way that the first derivative of the scale factor a(t) is increasing over time but the Hubble parameter H(t) is decreasing, and that this has the implication "The recession velocity of one chosen galaxy does increase, but different galaxies passing a sphere of fixed radius cross the sphere more slowly at later times". There's a more technical discussion of how these parameters are defined at https://en.wikipedia.org/wiki/Accelerating_expansion_of_the_universe#Technical_definition which mentions that physicists define "accelerating expansion" specifically in terms of the second derivative of the scale factor being positive, it doesn't require an increasing Hubble parameter.
On Fri, Dec 2, 2022 at 4:15 AM Alan Grayson <[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/7eb0dfae-1e78-4917-942a-a1d89faf424cn%40googlegroups.com > <https://groups.google.com/d/msgid/everything-list/7eb0dfae-1e78-4917-942a-a1d89faf424cn%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- 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/CAPCWU3KJv7hy7r_hc0Hq7VsVwuSsjnW_N8Yoz1Qz8ee002duEQ%40mail.gmail.com.
