Le mer. 11 sept. 2024, 09:56, Alan Grayson <[email protected]> a écrit :
> > > On Wednesday, September 11, 2024 at 1:44:39 AM UTC-6 Quentin Anciaux wrote: > > > > Le mer. 11 sept. 2024, 09:42, Alan Grayson <[email protected]> a écrit : > > > > On Tuesday, September 10, 2024 at 3:50:08 PM UTC-6 Quentin Anciaux wrote: > > > > Le mar. 10 sept. 2024, 23:19, Alan Grayson <[email protected]> a écrit : > > > > On Tuesday, September 10, 2024 at 2:19:42 PM UTC-6 John Clark wrote: > > On Tue, Sep 10, 2024 at 3:57 PM Alan Grayson <[email protected]> wrote: > > > *>> 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.* > > > *Galaxies are receding from the Earth at 70 km/sec for EACH megaparsec > distant from Earth they are. The further from Earth they are, the faster > they are moving away from us, so if they are far enough away they will be > moving faster than the speed of light away from us. * > > *> You're assuming the universe today is infinite,* > > > *NO! I said IF the entire universe is infinite today then it was always > infinite, and IF it was finite 10^-35 seconds after the Big Bang then it's > still finite today. I also said nobody knows if the entire universe is > infinite or finite. * > > > *>* *Hubble's law applies to the past, not to the future,* > > > *What the hell?! * > > > *How about an intelligent reply? Obviously, if the universe is infinite > today, it was always infinite. But that's what I am questioning. For > galaxies to fall out of view, they have to moving at greater than c. Now > they aren't receding that fast. How will they start moving that fast? > You're applying Hubble's law without thinking what it says. Just because a > galaxy is now receding at less than c, how will continued expansion > increase that speed to greater than c? AG * > > > The farther they are the faster they are receding from you, so as they > continue to get farther away they receed faster from you till the point > they receed faster than c and go out of your horizon. > > Quentin > > > *That's your claim, but, like I wrote, if say, the rate of expansion is > fixed, the separation distance isn't increasing faster than c. It's just > increasing. AG * > > > Just take the balloon example, it's a perfect explanation, any two points > receed faster from each other as the balloon inflates. > > > *If the rate of expansion is fixed, the distance along some equator > containing two separated galaxies increases linearly as a function of the > radial distance, s. So I don't see what you claim your model proves. AG * > You're correct that, with a fixed rate of expansion, the distance between two galaxies increases linearly as a function of time. However, the key point is that recession velocity depends on the distance between the galaxies. Using the balloon analogy: imagine two points on an inflating balloon. Even if the balloon expands at a constant rate, the farther apart the points are, the faster they move away from each other. This means the rate at which the distance between the two points increases is proportional to how far apart they are. So, as the distance between galaxies grows, their recession velocity increases. In an expanding universe, the same thing happens: even if the expansion rate is constant, galaxies that are farther apart recede faster. At large enough distances (like beyond the Hubble radius), the recession velocity will exceed the speed of light because the space between the galaxies is expanding faster. So, while the distance may increase linearly with time, the recession velocity still increases with distance, and at sufficiently large distances, it exceeds . This is how galaxies beyond a certain distance can recede faster than the speed of light, even with a constant rate of expansion. > > * John* K Clark See what's on my new list at Extropolis > <https://groups.google.com/g/extropolis> > > hwt > > > -- > 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/5485c7a2-a527-448a-b337-3c8c60466d73n%40googlegroups.com > <https://groups.google.com/d/msgid/everything-list/5485c7a2-a527-448a-b337-3c8c60466d73n%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/efc374c4-d738-4fb1-998d-ebf238e48d95n%40googlegroups.com > <https://groups.google.com/d/msgid/everything-list/efc374c4-d738-4fb1-998d-ebf238e48d95n%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/dbe32589-1ac8-41a8-89dc-fe75f37bc657n%40googlegroups.com > <https://groups.google.com/d/msgid/everything-list/dbe32589-1ac8-41a8-89dc-fe75f37bc657n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "Everything List" group. 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