On Sunday, July 20, 2025 at 1:42:22 PM UTC-6 John Clark wrote:
On Sun, Jul 20, 2025 at 2:38 PM Alan Grayson <[email protected]> wrote: *> I made no deductions about inflation. * *On July 14 you said "the theory of Inflation must be false, insofar as it alleges a huge initial expansion rate to account for the observed uniformity of the current universe", but perhaps you've changed your mind, and there is no disgrace in doing that.* That was either my typo or your misquote, since the rationale for inflation is pretty strong IMO. I'll check on that later today, after my laundry. I forget, but there's another important prediction of inflation, which is verified in the CMB. Do you recall what it is? AG *> it's generally accepted that the red shift we measure today left those galaxies well in the past, and AFAIK, has always been interpreted as due to expansion of the cosmos.* *Yes light left those galaxies long long ago, and during its multi billion year journey space has been expanding, and that spatial expansion produces a redshift. * * < It's obvious that in ancient times galaxies were much more closely separated than presently,* *Yes* * but Clark ALSO claims the rate of expansion was small at that time.* *Yes, back then the average distance between galaxies was less than it is now, and the rate at which that distance was increasing was also smaller. * I really don't see how the rate of expansion can be smaller today, since the measured value in ancient times is much larger than it is today, ignoring the new data from the late 1990's. AG *Well... if I'm being pedantic it's a little more complicated than that. In the late 1990s it was discovered that during the first 9 billion years of the universe's existence the rate of expansion of the universe was indeed slowing down just as you'd expect because gravity is attractive but then, about 5 billion years ago, there was a cosmic "jerk" (the rate of increase of acceleration) and the rate at which the universe was expanding started to increase. * *This can be explained if a property of empty space is that it has a negative pressure which according to Einstein causes space to expand, * Can you say more about negative pressure and its cause? AG *so the more space there is the larger the effect; but matter produces a positive pressure which causes the expansion to slow down, but the more space there is the more diluted matter becomes and the weaker this effect. As the universe expands dark energy, which wants the universe to expand faster, does not become diluted. But matter, which wants the universe to contract, does become diluted. And that produces a jerk. * *>The red shift of those galaxies seems to indicate otherwise,* *From that I must conclude that you still don't understand that there is a difference between a galaxy moving away from us through space and the space between us and the galaxy expanding, and you still don't understand that there's more than one way to create a redshift. * I clearly understand both issues, and have no problem with either. As Brent wrote, and we can agree, the red shift due to motion through space can be ignored. If the red shift observed came from the expansion of the cosmos, then what we observe with respect to the red shift was NOT caused in the ancient past, and this must be the basis for your claim, that the cosmos was not expanding fast at that time. If so, why do you assert that what we observe today, including the red shift, originated in the ancient past? I think my confusion is the generally held belief that the light we observe from ancient galaxies, originated in the ancient past, but the observed red shift is apparently an unstated exception. So, when it's claimed those ancient galaxies are receding rapidly, they're NOT referring to what was occurring ancient times, but NOW. AG *John K Clark See what's on my new list at Extropolis <https://groups.google.com/g/extropolis>* noo -- 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/53540eea-0010-43e4-bd16-fc01d7324175n%40googlegroups.com.
