On Sunday, September 15, 2019 at 6:36:25 AM UTC-6, Alan Grayson wrote: > > > > On Sunday, September 15, 2019 at 1:01:23 AM UTC-6, Jason wrote: >> >> >> >> On Sun, Sep 15, 2019 at 12:02 AM Alan Grayson <[email protected]> >> wrote: >> >>> >>> >>> On Saturday, September 14, 2019 at 4:34:28 PM UTC-6, Jason wrote: >>>> >>>> >>>> >>>> On Sat, Sep 14, 2019 at 3:06 PM Alan Grayson <[email protected]> >>>> wrote: >>>> >>>>> >>>>> >>>>> On Saturday, September 14, 2019 at 7:46:27 AM UTC-6, Jason wrote: >>>>>> >>>>>> >>>>>> >>>>>> On Sat, Sep 14, 2019, 4:36 AM Alan Grayson <[email protected]> >>>>>> wrote: >>>>>> >>>>>>> >>>>>>> >>>>>>> On Saturday, September 14, 2019 at 12:34:18 AM UTC-6, Jason wrote: >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> On Friday, September 13, 2019, Alan Grayson <[email protected]> >>>>>>>> wrote: >>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> On Friday, September 13, 2019 at 4:42:00 PM UTC-6, Jason wrote: >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> On Fri, Sep 13, 2019 at 8:25 AM Alan Grayson <[email protected]> >>>>>>>>>> wrote: >>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> On Friday, September 13, 2019 at 5:24:11 AM UTC-6, Bruno Marchal >>>>>>>>>>> wrote: >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> On 13 Sep 2019, at 04:26, Alan Grayson <[email protected]> >>>>>>>>>>>> wrote: >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> On Thursday, September 12, 2019 at 11:01:54 AM UTC-6, Alan >>>>>>>>>>>> Grayson wrote: >>>>>>>>>>>>> >>>>>>>>>>>>> >>>>>>>>>>>>> >>>>>>>>>>>>> On Thursday, September 12, 2019 at 7:45:22 AM UTC-6, Lawrence >>>>>>>>>>>>> Crowell wrote: >>>>>>>>>>>>>> >>>>>>>>>>>>>> On Thursday, September 12, 2019 at 4:20:46 AM UTC-5, Philip >>>>>>>>>>>>>> Thrift wrote: >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> On Wednesday, September 11, 2019 at 11:45:41 PM UTC-5, Alan >>>>>>>>>>>>>>> Grayson wrote: >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> https://www.wired.com/story/sean-carroll-thinks-we-all-exist-on-multiple-worlds/ >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> Many Worlds is where people go to escape from one world of >>>>>>>>>>>>>>> quantum-stochastic processes. They are like vampires, but >>>>>>>>>>>>>>> instead of >>>>>>>>>>>>>>> running away from sunbeams, are running away from probabilities. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> @philipthrift >>>>>>>>>>>>>>> >>>>>>>>>>>>>> >>>>>>>>>>>>>> This assessment is not entirely fair. Carroll and Sebens have >>>>>>>>>>>>>> a paper on how supposedly the Born rule can be derived from MWI >>>>>>>>>>>>>> I have yet >>>>>>>>>>>>>> to read their paper, but given the newsiness of this I might get >>>>>>>>>>>>>> to it. One >>>>>>>>>>>>>> advantage that MWI does have is that it splits the world as a >>>>>>>>>>>>>> sort of >>>>>>>>>>>>>> quantum frame dragging that is nonlocal. This nonlocal property >>>>>>>>>>>>>> might be >>>>>>>>>>>>>> useful for working with quantum gravity, >>>>>>>>>>>>>> >>>>>>>>>>>>>> I worked a proof of a theorem, which may not be complete >>>>>>>>>>>>>> unfortunately, where the two sets of quantum interpretations >>>>>>>>>>>>>> that >>>>>>>>>>>>>> are ψ-epistemic and those that are ψ-ontological are not >>>>>>>>>>>>>> decidable. There >>>>>>>>>>>>>> is no decision procedure which can prove QM holds either way. >>>>>>>>>>>>>> The proof is >>>>>>>>>>>>>> set with nonlocal hidden variables over the projective rays of >>>>>>>>>>>>>> the state >>>>>>>>>>>>>> space. In effect there is an uncertainty in whether the hidden >>>>>>>>>>>>>> variables >>>>>>>>>>>>>> localize extant quantities, say with ψ-ontology, or whether >>>>>>>>>>>>>> this localization is the generation of information in a local >>>>>>>>>>>>>> context from >>>>>>>>>>>>>> quantum nonlocality that is not extant, such as with >>>>>>>>>>>>>> ψ-epistemology. Quantum interprertations are then auxiliary >>>>>>>>>>>>>> physical axioms or postulates. MWI and within the framework of >>>>>>>>>>>>>> what Carrol >>>>>>>>>>>>>> and Sebens has done this is a ψ-ontology, and this defines >>>>>>>>>>>>>> the Born rule. If I am right the degree of ψ-epistemontic >>>>>>>>>>>>>> nature is mixed. So the intriguing question we can address is >>>>>>>>>>>>>> the nature of >>>>>>>>>>>>>> the Born rule and its tie into the auxiliary postulates of >>>>>>>>>>>>>> quantum >>>>>>>>>>>>>> interpretations. Can a similar demonstration be made for the >>>>>>>>>>>>>> Born rule >>>>>>>>>>>>>> within QuBism, which is what might be called the dialectic >>>>>>>>>>>>>> opposite of MWI? >>>>>>>>>>>>>> >>>>>>>>>>>>>> To take MWI as something literal, as opposed to maybe a >>>>>>>>>>>>>> working system to understand QM foundations, is maybe taking >>>>>>>>>>>>>> things too >>>>>>>>>>>>>> far. However, it is a part of some open questions concerning the >>>>>>>>>>>>>> fundamentals of QM. If MWI, and more generally postulates of >>>>>>>>>>>>>> quantum interpretations, are connected to the Born rule it makes >>>>>>>>>>>>>> for some >>>>>>>>>>>>>> interesting things to think about. >>>>>>>>>>>>>> >>>>>>>>>>>>>> LC >>>>>>>>>>>>>> >>>>>>>>>>>>> >>>>>>>>>>>>> If you read the link, it's pretty obvious that Carroll >>>>>>>>>>>>> believes the many worlds of the MWI, literally exist. AG >>>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> Carroll also believes that IF the universe is infinite, then >>>>>>>>>>>> there must exist exact copies of universes and ourselves. This is >>>>>>>>>>>> frequently claimed by the MWI true believers, but never, AFAICT, >>>>>>>>>>>> proven, or >>>>>>>>>>>> even plausibly argued. >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> The idea comes from Tegmark, and I agree with you, it >>>>>>>>>>>> necessitate more than an infinite universe. It requires also some >>>>>>>>>>>> assumption of homogeneity. >>>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> Our universe is, on a large scale, homogeneous. But it can't be >>>>>>>>>>> infinite since it has only been expanding for finite time, 13.8 BY. >>>>>>>>>>> I had a >>>>>>>>>>> discussion with Brent about this some time ago, and he claimed >>>>>>>>>>> finite in >>>>>>>>>>> time doesn't preclude infinite in space. I strongly disagree. >>>>>>>>>>> Perhaps I am >>>>>>>>>>> missing something. Wouldn't be the first time. AG >>>>>>>>>>> >>>>>>>>>> >>>>>>>>>> I think what you may be missing is that in popular (but >>>>>>>>>> misleading) accounts of the BB they often say everything originated >>>>>>>>>> from a >>>>>>>>>> point, rather than everywhere at once. To say "everything came from >>>>>>>>>> a >>>>>>>>>> point" is at best only valid for describing the observable universe >>>>>>>>>> (or any >>>>>>>>>> finite portion of the universe) but is invalid to extrapolate it to >>>>>>>>>> the >>>>>>>>>> whole universe, which may be spatially infinite. >>>>>>>>>> >>>>>>>>> >>>>>>>>> I am not assuming our universe began from a mathematical point, >>>>>>>>> but I do assume that 13.8 BYA it was very very small, the observable >>>>>>>>> and >>>>>>>>> unobservable parts. >>>>>>>>> >>>>>>>> >>>>>>>> Why do you assume this? Most cosmologists make no such >>>>>>>> assumption. Under the concordance (standard assumed) model of >>>>>>>> cosmology, >>>>>>>> space is infinite. >>>>>>>> >>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> I don't think there is an implied disconnect between our >>>>>>>>> measurements of the CMBR and what an observer would measure in parts >>>>>>>>> we >>>>>>>>> have no access to. It was everywhere hot and dense, and very very >>>>>>>>> small. >>>>>>>>> >>>>>>>> >>>>>>>> There's no observational motivation for the universe being very >>>>>>>> very small at the beginning. It could have been small, large or >>>>>>>> infinite, >>>>>>>> for all we know. >>>>>>>> >>>>>>> >>>>>>> I've never read a description of inflation where the universe is >>>>>>> described as very large spatially when it initiates. Never. It's always >>>>>>> claimed it begins a few Planck durations (10^-43 seconds) after the BB, >>>>>>> at >>>>>>> which time the spatial diameter is many orders of magnitudes smaller >>>>>>> than >>>>>>> the diameter of a proton. It then expands to the diameter of the Earth >>>>>>> or >>>>>>> the Solar System before terminating, all this occuring within the first >>>>>>> second after the BB. AG >>>>>>> >>>>>> >>>>>> I think we need to clearly distinguish between three periods, which >>>>>> are frequently confused: >>>>>> >>>>>> 1. "quantum vacuum phase" Size: ??? Time: ??? >>>>>> If inflation began as a fluctuation in the vacuum, the vacuum was a >>>>>> pre-existing initial condition. We can say nothing of it's size or how >>>>>> long >>>>>> it has existed. Alternatively, this vacuum may have already been in a >>>>>> state of exponential expansion and required no fluctuation to get >>>>>> started. >>>>>> >>>>>> >>>>>> 2. "Inflation start" Size: (min = Planck size, max = ???) Time: (min >>>>>> = fraction of second before hot stage of BB, max = finite but otherwise >>>>>> unlimited time ago). >>>>>> If inflation started as a fluctuation it could have started very >>>>>> small, but it would then grow exponentially forever. How big it was >>>>>> when >>>>>> it stopped for us we can't say, but we can guess it had to have gone on >>>>>> for >>>>>> at least 10^-32 seconds to fit with observations. This is only the >>>>>> minimum >>>>>> time, there's no known upper bound. There's not necessarily any cooling >>>>>> during this time as the heat doesn't enter the picture until inflation >>>>>> begins to stop somewhere. >>>>>> >>>>>> 3. "Local inflation end", Size of inflating space: (undefined but >>>>>> ever growing), Size of pocket from outside: (finite but growing), >>>>>> Apparent >>>>>> size of pocket from inside: (finite or infinite depending on shape of >>>>>> the >>>>>> universe), Time: 13.8 BY ago. >>>>>> >>>>>> The "T = 0 of the BB" no longer makes sense in the inflation picture, >>>>>> the only place we can begin to speak of absolutes with time is when we >>>>>> speak of the local end to inflation in our pocket. >>>>>> >>>>>> Jason >>>>>> >>>>> >>>>> I'll say it again. One the main reasons to posit inflation is to >>>>> explain the observable large scale homogeneity of a universe that is now >>>>> NOT causally connected. If the universe was very very tiny when inflation >>>>> started, it WAS then causally connected, >>>>> >>>> >>>> The *observable* part of the universe is posited to have once been >>>> causally connected to come to thermal equilibrium but not necessarily the >>>> entire universe. >>>> >>> >>> OK, but based on our best measurements, we live in a closed, >>> accelerating and expanding hypersphere, since the curvature is NOT zero and >>> NOT negative. >>> >> >> Do you have a citation for this? All the estimates I am familiar with >> assume a flat or slightly open shape. >> >> >>> I prefer to go with what we think we know, rather than with a model >>> which is completely speculative. AG >>> >> >> Which is what? >> > > I am looking for a citation, but I recall that someone on this thread > stated the measured curvature is close to zero, but POSITIVE. AG > >> >> >>> >>>> >>>>> and inflation preserved the homogeneity. This is what Guth was trying >>>>> to solve with inflation, among other problems, such as no detectable >>>>> monopoles. This entire logic breaks down if one assumes an infinite >>>>> universe at the time of inflation. >>>>> >>>> >>>> Correct, using inflation and previous causal connectedness does not >>>> produce for homogeneity of temperature to all parts of the universe if the >>>> universe is infinite. >>>> >>> >>> So far, as I just stated, our best evidence >>> >> >> There's no evidence either way, as far as I am aware, which is why i is >> still considered an open question. If you can point me to some evidence I >> would be interested. >> >> >>> does NOT suggest an infinite universe. AG >>> >> >> What are you calling as the universe here? How are you defining it? >> > > I am referring to our bubble, which arose with the BB, and refers to the > observable and UNobservable regions (not to the possibly infinite substrate > from which it arose). AG > >> >> >>> >>> >>>> At best it can only extend to some finite region of that universe. >>>> But once you are working in an inflationary model, you already have >>>> accepted there is a large scale where the universe is not homogenous >>>> (pocket regions vs. the rapidly inflating regions of vacuum). >>>> >>> >>> I don't see why assuming inflation implies acceptance of large parts of >>> the UNobservable universe which is NOT homogeneous. AG >>> >> >> Because decay events of the vacuum do not happen everywhere at once, this >> leads to isolated "pocket universes" separated by exponentially expanding >> space. The inhomogenity I am referring to are the different parts of the >> vacuum in different energy states. >> >> >>> >>>> >>>>> In this case, the infinite universe was always homogeneous even though >>>>> it was never causally connected. >>>>> >>>> >>>> That is another possibility that avoids inflation as an explanation of >>>> homogeneity: To simply assume everything at all places began at the same >>>> temperature and density. >>>> >>> >>> If so, why did Guth think homogeneity needed an explanation? On its >>> face, thermal equilibrium for a non causally connected universe seems >>> improbable. AG >>> >> >> It came for free, with the other explanations. On its own, I am not sure >> it would be justified to trade one assumption for another, but inflation >> replaced 4 or 5 assumptions with a single one, which is its main strength. >> >> >>> >>>> >>>>> Further, how could it have been so hot 380,000 years after the BB if >>>>> it wasn't dense at that time? >>>>> >>>> >>>> Actually the universe was not very dense at the time of 380,000 years. >>>> It was billions of times more sparse than Earth's atmosphere. Each time >>>> the scale factor >>>> <https://en.wikipedia.org/wiki/Scale_factor_(cosmology)> halves going >>>> backwards in time, the temperature doubles, and the density increases by a >>>> factor of 8 (2 cubed). You can follows this backwards at least until the >>>> temperature is about 10^27 K, far far hotter and denser than 380,000 >>>> years, >>>> back to a time just a fraction of a second after inflation ended. >>>> >>> >>> Yes, it was far hotter and denser just after the BB, than at 380,000 >>> years. >>> >> >> Okay. >> >> >>> But contrary to what you allege above and below, it must have far hotter >>> and denser at 380,000 years, than it is today, 2.7 deg K, so hot and dense >>> that it was opaque to light. >>> >> >> I'm not sure how this is contrary to what I say above and below... I >> agree it was hotter and denser the farther back you go. >> > > And smaller as well? (BTW, "smaller" can't be a property of a spatially > infinite universe.) It had to have gotten smaller to explain its present > homogeneity. I want to avoid the assumption that homogeneity can arise > spontaneously in a causally DIS-connected universe, the one we observe. And > I don't believe that at 380,000 years it was less dense than our atmosphere > (as you earlier alleged). AG > >> >> >>> I am just saying that it does seem to be cooling as it expands, >>> >> >> Yes. >> >> >>> and the curvature data seems to imply smallness just after the BB. >>> >> >> What curvature data are you referring to? The latest Planck data say the >> curvature is flat to within the limits of our measurement accuracy. Is >> there a new result that indicates positive curvature? >> > > "Flat" means curvature is exactly zero; that is, flat like a Euclidean > plane. But if we measure slightly positive, which I think is the case, it > must be a closed hyperspace, but HUGE. Physicists tend to equate "almost > flat", which if true would mean a huge spherical hyperspace, with Euclidean > flat. This is a persistent error. AG > > What I don't understand is why, a universe with accelerating expansion, > must be open, like a saddle. Why can't a spherical hyperspace retain its > closure if its expansion is accelerating? AG > >> >> >>> Moreover, applying the Cosmological principle, it couldn't have been >>> homogeneous on large scale in the finite observable region, and at the same >>> time infinite and non-homogeneous in regions we can't observe. AG >>> >> >> It all comes down to scale. At the scale of stars or galaxies, the >> universe is non homogeneous, on the scale of super clusters and above it >> is, but at larger scales of inflating vacuums and pocket universes, again >> it is non homogeneous, but perhaps if you zoom out far enough the picture >> becomes homogeneous again. The non-homogeneous part I am referring to can >> be seen as the spiky image, a rendering of eternal inflation: >> https://www.preposterousuniverse.com/blog/2011/10/21/the-eternally-existing-self-reproducing-frequently-puzzling-inflationary-universe/ >> > > I would forget about inflating vacuums and pocket universes, which are > totally speculative, and focus on what we can observe -- which, on a large > scale, is homogeneous. Why trash the Cosmological Principle by appealig to > unobservable phenomena? AG > >> >> Jason >> >> >>> >>>> >>>>> An infinite universe right after the BB would be COOL, >>>>> >>>> >>>> Right after inflation predicts it could have been as high as 10^27 >>>> degrees. >>>> Our observations agree with our theory which predicts at about 1 second >>>> it was 10s of billions of degrees, falling to 10s of millions of degrees >>>> after 20 minutes. >>>> At 380,000 years the temperature was about 3000 degrees. >>>> At 13.8 billion years it is about 2.7 degrees. >>>> >>>> From: http://kias.dyndns.org/astrophys/cosmology.html >>>> eventtemperature (K)scale factornow / scale factorthentime >>>> strong forces freeze out 1027 3.7 * 1026 10-35 s >>>> weak forces freeze out 1015 3.7 * 1014 10-10 s >>>> protons, neutrons freeze out 1013 3.7 * 1012 0.0001 s >>>> neutrinos <http://kias.dyndns.org/astrophys/particles.html> decouple 3 >>>> * 1010 1.1 * 1010 1 s >>>> electrons freeze out 6 * 109 2.2 * 109 100 s >>>> primordial 2H, 4He form 9 * 108 3.3 * 108 2-15 minutes >>>> >>>> eventtemperature (K)scale factornow / scale factorthentime >>>> photons decouple, atoms form 3000 1091 377000 years >>>> first stars 60 10.4 109 years >>>> today 2.73 1 1.378 * 1010 years >>>> >>>> and COOLER after 380,000 years had elapsed. All of the foregoing makes >>>>> a decent case for a universe which was very very tiny right after the BB. >>>>> AG >>>>> >>>> >>>> I still see no connection between the temperature at time 380,000 >>>> years, and the size of the universe. Can you do more to explain more why >>>> you think there is a relation? I can see how you might relate the initial >>>> temperature and density at an earlier time to the temperature and density >>>> after 380,000 years, but I am not seeing how you relate the size of the >>>> universe to either the temperature or density at time 380,000 years. >>>> >>> *Oh, because the temperature is decreasing from just after the BB to 380,000 years, we need a very small universe to inflate to explain the current homogeneity. Otherwise the present large scale homogeneity is only explicable by appealing to highly improbable chance in a causally disconnected universe, our present universe. AG *
> >>>> Jason >>>> >>> -- >>> 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/666ba0a0-918d-422f-b2ed-f0ded39b82b1%40googlegroups.com >>> >>> <https://groups.google.com/d/msgid/everything-list/666ba0a0-918d-422f-b2ed-f0ded39b82b1%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/b9b2cdc5-b570-4b8a-9d39-6ffb9491a37b%40googlegroups.com.
