On Friday, November 28, 2025 at 6:06:56 AM UTC-7 Alan Grayson wrote:
On Thursday, November 27, 2025 at 8:01:08 PM UTC-7 Alan Grayson wrote: On Saturday, August 30, 2025 at 5:20:04 AM UTC-6 John Clark wrote: On Sat, Aug 30, 2025 at 6:56 AM Alan Grayson <[email protected]> wrote: *The following quote is from Expansion of the universe <https://en.wikipedia.org/wiki/Expansion_of_the_universe?utm_source=chatgpt.com> :* *"The very earliest expansion, called inflation <https://en.wikipedia.org/wiki/Inflation_(cosmology)> saw the universe suddenly expand by a factor of at least 1026 in every direction about 10−32 of a second after the Big Bang. Cosmic expansion subsequently decelerated to much slower rates, until around 9.8 billion years after the Big Bang (4 billion years ago) it began to gradually **expand more quickly <https://en.wikipedia.org/wiki/Accelerating_expansion_of_the_universe>, and is still doing so." * *The following quote is from** Accelerating expansion of the universe <https://en.wikipedia.org/wiki/Accelerating_expansion_of_the_universe>:* *"The accelerated expansion of the universe is thought to have begun since the universe entered its dark-energy-dominated era <https://en.wikipedia.org/wiki/Dark-energy-dominated_era> roughly 5 billion years ago"* *> I never disputed that conclusion; only yours, that it implies that after the galaxies formed, the universe was expanding very slowly.* *Expanding "very slowly" compared with the expansion of the universe during inflation certainly. I will now make a statement that you dispute that I am nevertheless absolutely certain is true: * *Today galaxies are expanding faster than they were before galaxies started expanding faster. * *The reason I would be willing to bet my life on the above statement being true is because all tautologies are true.* *> Sure, after that the expansion slowed due to gravity, but the discovery of the accelerated expansion says NOTHING about the much earlier rate of expansion. AG * *Yet more evidence that you don't read what I write, not even the parts that I underline. * *"Cosmic expansion subsequently decelerated to much slower rates, until around 9.8 billion years after the Big Bang (4 billion years ago) it began to gradually **expand more quickly <https://en.wikipedia.org/wiki/Accelerating_expansion_of_the_universe>, and is still doing so." * *Sorry, but I'm still confused about what, exactly, Hubble's law is telling us. On its face, it's saying that on average, the farther away galaxies are, the faster is their recessional velocity. Does this mean that in the past, after the very short period of inflation ended, and ignoring 1998 measurements, they were receding faster than they are today? TY, AG* *I think I get it. The recessional velocity is simply a function of distance, so regardless of the rate of expansion of the universe, the recessional velocity will keep increasing, but at different rates, depending on the rate of expansion and how distant a galaxy is. Even assuming the effect of gravity is to slow the rate of expansion, and even if that rate increases as shown by the 1998 measurements, the recessional velocity will increase or decrease in its RATE, but in absolute terms its value must increase if the universe continues to expand. In sum, although we're viewing those galaxies as they were billions of years ago, Hubble's law tells us how fast they are receding in the present, aka NOW. (This is what was puzzling me; whether or not the high recessional velocity of distant galaxies is occurring now or in the distant past.) Finally, since the galaxies were closely located relatively soon after inflation ended, the magnitude of mutual recessional velocity at that time was positive, but small. AG* *Clark; do me a favor and post if you agree with my analysis of Hubble's law. TY, 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 visit https://groups.google.com/d/msgid/everything-list/fb8ee431-4251-4fa1-bbf5-0e6d3931372cn%40googlegroups.com.
