On Saturday, September 21, 2024 at 9:58:49 PM UTC-6 Alan Grayson wrote:
On Saturday, September 21, 2024 at 6:41:36 AM UTC-6 John Clark wrote: On Fri, Sep 20, 2024 at 6:37 PM Alan Grayson <agrays...@gmail.com> wrote: *>> This entire business started by you asking what would happen at T=0 if the universe started running backwards and obviously, regardless of if space is finite or infinite, space would have to expand infinitely fast because at T=0 it would have a zero amount of time to expand from nothing to something.* *> Not exactly. I figured that since the universe is expanding, we could run to clock backward and imagine enclosing it in a sphere,* *If you're assuming that at T=0 the ENTIRE universe could be contained in a sphere of finite size then you're assuming that space is finite, the very thing you're trying to prove. * *No. Not assuming that. Since there's universal agreement that our bubble is expanding, you can always go back in time, to any time, say T = 10 BY, and put a finite sphere around it. The question is whether that's the whole universe or just the observable part, and whether any part can be infinite in spatial extent and be created. Apparently, you love spooky action at a distance. There's no accounting for taste. AG* *> say, establishing that it is finite, hence NOT flat, since flat implies infinite in spatial extent.* *Not necessarily. In the "3-torus model" space is flat, and space is finite, and space has no boundary, BUT it also has no edges; * *My plan for today was to discuss flatness in the context of the torus, but you beat me to it. If we use Euclid's 5th postulate to define flatness, using two lines and a third one which crosses the other two, the torus will be as you describe, flat and finite. But when physicists define flatness, they use the concept that a beam of light going in a straight line will never return to its source. This is what Lawrence Krauss says in one of his videos. AG * *a 2-D analogy of this would be a video game where if you go too far to the extreme right you disappear and then instantly reappear on the extreme left. However nobody knows what the large scale topology of the universe is, not even you. * *Before the discovery of Dark Energy and the acceleration of the universe,* *Dark Energy, like Inflation, hasn't been "discovered". Rather, they're both ad hoc models to explain unsolved problems. I would conjecture that GR might be able to establish that gravity can be repulsive and attractive, and their respective influence over time might change. Maybe it already allows this, in which case, it's possible that both could establish an expanding universe, even Inflation, as well as the force slowing down the expansion. It would be a great doctoral thesis. AG* * people thought if you knew the large scale topology of the universe then you could figure out if it was infinite or finite; if it was flat then it was infinite, if it was positively curved then it was finite, and if it was negatively curved then it was infinite. But now things are not that simple and there is not a clear cut relationship between shape and the finite versus infinite question. **Even a positively curved universe could be open and expand forever if the universe is accelerating. And flat doesn't necessarily mean infinite.* *Sometimes physicists are sloppy in their math, and what they call flat, is really asymptotically flat, which is really slightly curved and getting closer to flat. For me, AFAICT, our bubble is closed and approximately spherical for reasons previously stated somewhere; because isotropy is approximately uniform. AG* *> we can prove the universe is NOT flat using a purely logical argument. No need to do any measurements.* *That's what the ancient Greeks thought, experiments are unnecessary, and that attitude is why physics didn't advance one inch in over 1500 years. I don't care how beautiful a philosophical argument is, if measurement says an idea is wrong then it's wrong. * *I wish you would do some serious thinking on this issue. Because the universe is huge, our measurements can't distinguish flat from slightly curved**. Think of the Earth expanding hugely, so huge that it would impossible to distinguish flat from slightly curved. But you can't think clearly because your focus is NOT on trying to understand what I am saying, but in trying to prove I am mistaken. **AG * *> I sent this analysis to a professor emeritus whose main interest is in cosmology who is associated with Case Western University. He replied that my analysis dealt only with the observable universe and that the universe could be infinite in spatial extent, presumably when one considers the unobservable part.* *And that is why, as I said before, when Alan Guth wrote that long ago the universe was just the size of a proton he meant the OBSERVABLE universe. * *And you KNOW this how? AG * *> I then realized that the unobservable part was very likely caused by Inflation, and therefore the entire universe would remain finite provided we ran the clock backward, prior to Inflation. * *And as I said before, IF the universe was finite before inflation then it was finite after it, and IF the universe was infinite before inflation it was infinite after inflation.* *You've made this statement before, and I told you I agree. What's the point in repeating it? AG* *So inflation is irrelevant in a finite versus infinite discussion, * *If the unobservable part came into existence via Inflation we agree it's finite, but the "expert" at Case Western thinks otherwise -- that the unobservable part is infinite in spatial extent. That was the obvious implication of his critique of my claim, that the bubble we're in, both parts, are finite. AG* *as should've been obvious to you because during inflation although the universe grew by an astronomically large amount that amount was FINITE.* *Of course. I never claimed otherwise. AG * * > the concept of a created universe, one which comes into being, which is infinite in spatial extent, assumes a type of singularity which I believe is non-physical and can't be realized;* *1)A belief is not a proof. * *Do you believe Euclid's 5th postulate? That's just an example of many things we believe that we can't prove. AG * *2) Apparently you believe a nothing to something singularity, where things change INFINITELY (not just astronomically) fast is possible, so why is infinite space so unbelievable?* *I don't deny infinite space; just that it can't happen instantaneously. It would be spooky action at a distance, on steroids. So, if infinite space exists, it would be uncreated. In fact, I tend to think the part of the universe from whence our bubble arose, is infinite in space and time, and UNCREATED. AG* *3) Modern physics says a singularity occurred at T =0, but NOBODY believes that is the last word on the subject! Everybody believes we're missing something, but nobody knows what. * *> So, the professor apparently doesn't realize that his critique of my original analysis implies that his claim that the universe might be infinite in spatial extent, contains an implicit denial it had a beginning, called the Big Bang.* *Alan, did it ever occur to you that a physics professor at Case Western University who spent his life studying this subject MIGHT know more about it than you do? * * Sure, but obviously he hasn't thought deeply enough on the issues I raised. If you think "experts" are flawless, you're a fool. AG * *> I haven't written him again to relieve him of his apparent misconception, though I might.* *Crackpots always believe they know more about a subject than the experts do, and to be fair sometimes they actually do and calling them a crackpot is a libel, but for every Galileo there are 6.02*10^23 crackpots. * *I am hardly a crackpot to argue against infinite and instantaneous creation of space, which is spooking action at a distance, in steroids. AG* *> I did write Alan Guth about a week ago, asking if he assumed the entire universe, or just the observable part existed, when Inflation began, at around 10^-35 seconds after the Big Bang, when the universe was around the size of a proton, or possibly smaller. So far he hasn't replied. * *Gee I wonder why. * *Now you sound like one of those right-wing nuts who think mockery is an argument. Maybe he gets tons of emails. Maybe my question annoys him. I asked if he assumes that just the observable universe is around the size of a photon when Inflation began, or if he also includes the unobservable part. You claim he assumes just the observable universe, but you really don't know this, and he doesn't mention this issue in his lectures, which, presumably you haven't viewed. AG* *And yes that is a singularity however in physics, unlike pure mathematics, when you run into a singularity what that is really telling you is that there is some unknown physics going on that you don't understand, or don't understand well enough. Everybody knows something is wrong but nobody knows what. * *By the way when people, like me, say that because of AI we're heading towards a Singularity they are using poetic license, things in general and society in particular won't really be changing infinitely fast, just faster than the human meat brain can comprehend. * *Just to be clear; one assumption I am making is that the unobservable universe came into being during Inflation, and is therefore finite in spatial extent. Another is that the observable universe is finite, since we can enclose it by a finite sphere. Together they** imply that the global geometry of the universe cannot be flat. **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 everything-list+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/97783af0-64de-4485-87e0-d367cf629f2fn%40googlegroups.com.
