On Tuesday, September 10, 2024 at 10:41:22 AM UTC-6 John Clark wrote:
On Tue, Sep 10, 2024 at 9:43 AM Alan Grayson <[email protected]> wrote: *>> even if the rate of expansion stopped increasing it would still be true that some galaxies we can see today we won't be able to see tomorrow. * *> But you haven't explained WHY that is the case. AG * *Even if you ignore Dark Energy and postulate that the Hubble constant really is constant, every object a megaparsec away (3.26 million light-years) is moving away from us at about 70 kilometers per second. So if you try to look at objects a sufficiently large number of megaparsec away you will fail to find any because they are moving away from us faster than the speed of light.* *That was in the past. At present, the universe is expanding at about 70 km/sec. Why should galaxies now in our view, disappear? AG* *>> If the entire universe, observable plus unobservable, is infinite today then it must've been infinite even before inflation started, it must've been infinite from the first Planck Time Instant of its creation. I think most cosmologists would say that at the largest level space is curved into some unknown shape but inflation has flattened it out so much the curvature is too small to ever be detected. * *> You're assuming what I'd like to see argued.* *In the above what specifically do you think I'm assuming? * *You're assuming the universe today is infinite, which is what I don't believe, since it started very small and Guth doesn't say it was infinite in the past. AG * *> Guth says Inflation started at t = 10^-35 seconds and the universe was around the size of a proton.* *I'm certain Guth meant the size of the OBSERVABLE universe was the size of a proton at 10^-35 seconds. But if the entire universe, observable plus unobservable, is infinite now then it must've been infinite then. Nobody knows if the universe is finite or infinite. * *That's what you don't know! AFAICT, Hubble's law applies to the past, not to the future, plus you don't know what Guth meant. AG * *> I think the huge expansion created the unobserved region since space must have expanded greater than the speed of light. AG * *During inflation the universe expanded VASTLY faster than the speed of light, but even without inflation we still wouldn't be able to see things further than 13.8 billion light years away for obvious reasons. * John K Clark See what's on my new list at Extropolis <https://groups.google.com/g/extropolis> RRO -- 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/93de5232-909f-4490-9d3e-3ceab574d030n%40googlegroups.com.
