On Saturday, September 14, 2019 at 11:19:47 AM UTC-6, stathisp wrote: > > > > On Sat, 14 Sep 2019 at 22:57, Jason Resch <[email protected] > <javascript:>> wrote: > >> >> >> On Sat, Sep 14, 2019, 2:44 AM Alan Grayson <[email protected] >> <javascript:>> 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. >>>> >>> >>> 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. >
You're positing a singularity. AG > > >> 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 [email protected] <javascript:>. >> 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 [email protected]. 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