On Sat, 14 Sep 2019 at 22:57, Jason Resch <jasonre...@gmail.com> wrote:
> > > On Sat, Sep 14, 2019, 2:44 AM Alan Grayson <agrayson2...@gmail.com> wrote: > >> >> >> On Saturday, September 14, 2019 at 12:34:18 AM UTC-6, Jason wrote: >>> >>> >>> >>> On Friday, September 13, 2019, Alan Grayson <agrays...@gmail.com> 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 <agrays...@gmail.com> >>>>> 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 <agrays...@gmail.com> 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. >>> >> >> If the universe is expanding, it had to be smaller in the past. >> > > Things were closer together in the past. It's more accurate to think of > the situation as distances stretching rather than the universe expanding. > Because if the universe is infinite then technically speaking it isn't > expanding in size. Yet whether finite it infinite, things in it are growing > apart. It is as if the space inside was self-reproducing. > > If it has been expanding for finite time, its spatial extent must be >> finite, >> > > If the universe is finite now it's always been finite. If it's infinite > now it's always been infinite. It is true it cannot jump from finite to > infinite. The question is what was it's size at the start. This is an open > question. > Unless it was finite in size and infinitely dense and at some point it expanded infinitely fast. > like a huge hypersphere. All the models I see pictorially illustrated, >> have it much much smaller than it presently is. AG >> > > The hypersphere model is a good demonstration of the mechanics of > expansion, but whether the universe is a finite hypersphere, an infinite > flat space, or an outwardly curved infinite space is unknown. Our > measurements suggest space is flat to within 0.4%. This implies it would > have had to be much flatter in the past. That suggests that the universe > is much larger than the observable part, and the extreme flatness is one of > the problems inflation solves. The question of "the shape of the universe" > is the very question if the spatial geometry, is it a hypersphere, flat, or > saddle shaped? This is another unknown, but the working assumption if the > standard cosmological model is that it is flat. > > > >>>> 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. >>> >> >> It was opaque just before 380,000 years, when the CMBR emerged, precisely >> because it was hugely hot and dense, so much so that light could get out. >> Is this not observational evidence? AG >> > > The universe becoming transparent at 380,000 years is strongly confirmed, > we can see it. We can confirm through observation our ideas concerning a > much hotter earlier phase up to about one second, which confirms among > other things the fraction of the primordial elements. > > Going back further things get less certain since we can't tie our > predictions to observations, and eventually our theories break down as the > temperatures would approach "absolute hot" and the blackbody photons become > so energetic that their wavelength would be less than a Planck length and > anything they touch recieves so much energy it becomes a black hole. To go > beyond this time we would need a quantum theory of gravity. > > But practicality all cosmologists think it is an over extrapolation to > reach the singularity at time zero (they don't think that happened). > > That the universe eventually fell below 3000 degrees (at time 380,000 > years) and became transparent, while in evidence, implies nothing of the > universe's size. Only that it has been cooling as a result of space > expanding. A particle collision between two particles being separated by a > growing space will each bounce away with less energy, just like gas > particles hitting the wall if an expanding piston. > > >>> >>>> If it were infinite at that time, its temperature would have been near >>>> absolute zero. AG >>>> >>> >>> I think you're working under the assumption that some finite amount of >>> energy was injected into space at one particular point. This is not what >>> the big bang theory says, rather all space (everywhere there was space), >>> was equally hot and dense. >>> >> >> I am not assuming what you allege. >> > > Okay. > > Yes, all space was hot and dense, but much smaller in spatial extent than >> today. Just play the movie backward. AG >> > > It's more correct to say things were closer together in the past than to > say anything of the universe's size. Because to extrapolate from average > closeness to size only works in the case of a finite universe. > > I invite you to try playing the movie backwards for an infinite universe. > If things get closer rewinding the clock, it's still infinite. Cut the > "scale factor" in half as many times as you like and the size would remain > infinite. > > > >>> Inflation modifies the picture a bit where the vacuum of space expands >>> rapidly due to its high energy density (which suggests a negative >>> pressure). Under the equations of GR, such a state would expand itself >>> exponentially. Eventually parts of this vacuum decay to a lower energy >>> density, and this dump of energy into space gives us the early hot stage of >>> the big bang. >>> >>> We don't know how big this initial inflating space was, but if inflation >>> is right, most of the universe is still experiencing exponential growth. >>> >>> Each pocket universe may be finite in volume, but extends infinitely in >>> the time direction. >>> >> >> Then why is there general agreement that the age of our bubble is 13.8 BY? >> > > That time (13.8 BY) can now be viewed as the time since inflation ended > (in our pocket). But we don't know how long it's been since inflation > started. It is believed to have started a finite time ago, but we can't say > when. > > In the video with Guth, he draws a series of concentric parabola shapes, > each one is a successive "now" for observers in the pocket. The length of > those lines is infinite because they curve upwards borrowing their extent > into the future time dimension, but to observers within that distance is > perceived as spatial. > > >> >>> As Alan Guth explains, GR can warp things in the internal view of each >>> pocket universe such that the time and space dimensions flip, the infinite >>> time dimension within the pocket universe can give rise to the appearance >>> of infinite space, and the finite space appears as finite time: >>> >>> https://youtu.be/rfeJhzPq3jQ >>> >> >> Time might, and probably does extend into an infinite future, but not >> into an infinite past. Otherwise, cosmologists wouldn't agree that the age >> of our bubble is 13.8 BY. What do you think that *measurement* means? AG >> > > I agree with that. There's strong evidence for our pocket being 13.8 BY > old, and arguments exist for why the universe should not be past eternal. > > 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 everything-list+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/everything-list/CA%2BBCJUjvW5pQ7v4Ex490SfUFOcBeUF5EJkxQzsVYyFHXgHmbXQ%40mail.gmail.com > <https://groups.google.com/d/msgid/everything-list/CA%2BBCJUjvW5pQ7v4Ex490SfUFOcBeUF5EJkxQzsVYyFHXgHmbXQ%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- Stathis Papaioannou -- 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. 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