On Thursday, October 3, 2019 at 4:22:20 PM UTC-6, Lawrence Crowell wrote: > > On Thursday, October 3, 2019 at 7:59:51 AM UTC-5, Alan Grayson wrote: >> >> >> >> On Thursday, October 3, 2019 at 3:45:41 AM UTC-6, Lawrence Crowell wrote: >>> >>> On Wednesday, October 2, 2019 at 7:31:56 PM UTC-5, Bruce wrote: >>>> >>>> On Thu, Oct 3, 2019 at 10:14 AM Lawrence Crowell < >>>> [email protected]> wrote: >>>> >>>>> On Wednesday, October 2, 2019 at 6:41:32 PM UTC-5, Bruce wrote: >>>>>> >>>>>> On Thu, Oct 3, 2019 at 9:21 AM Lawrence Crowell < >>>>>> [email protected]> wrote: >>>>>> >>>>>>> On Wednesday, October 2, 2019 at 5:46:50 PM UTC-5, Bruce wrote: >>>>>>>> >>>>>>>> On Thu, Oct 3, 2019 at 3:03 AM Alan Grayson <[email protected]> >>>>>>>> wrote: >>>>>>>> >>>>>>>>> >>>>>>>>> In this case I was just responding to Bruce's certainty that >>>>>>>>> inflation is mostly a red herring. I highly respect his opinions, but >>>>>>>>> in >>>>>>>>> this case, based on my study of this particular issue, I disagree. I >>>>>>>>> am >>>>>>>>> open to being proved wrong, but insults don't cut it. At least you >>>>>>>>> agree >>>>>>>>> that inflation does explain homogeneity. Aren't you curious about >>>>>>>>> Bruce's >>>>>>>>> take on this particular issue? AG >>>>>>>>> >>>>>>>> >>>>>>>> Inflation can result in an increase in flatness and homogeneity. >>>>>>>> But that is relevant only if flatness and homogeneity were problems in >>>>>>>> need >>>>>>>> of explanation. >>>>>>>> >>>>>>>> Bruce >>>>>>>> >>>>>>> >>>>>>> The real problem is how did disparate regions of the universe become >>>>>>> uniform when there would have been no causal connection between them. >>>>>>> In >>>>>>> particular with homogeneity inflation provides a mechanism whereby >>>>>>> deviations from homogeneity and isotropy are uniform. >>>>>>> >>>>>> >>>>>> Fine. Provided they were not uniform at the start. It is all a matter >>>>>> of distributions and in initial conditions. And you know nothing about >>>>>> either, so why solve a problem before you know it exists? Besides, can >>>>>> you >>>>>> achieve thermal equilibrium in a non-equilibrium state in 10^{-35} sec? >>>>>> >>>>>> Bruce >>>>>> >>>>> >>>>> Inflation started on a fiducial at 10^{-36}sec and lasted until >>>>> 10^{-32} sec. Since the particle fields were near the Planck scale in >>>>> energy this inflationary cycle lasted some 10^{10} times the >>>>> periodicities >>>>> of fields. That is enough to approximately have thermal equilibrium. >>>>> >>>> >>>> The problem is not the periodicity of the fields. The problem is the >>>> uniformity of the initial conditions. As Sabine points out, inflation just >>>> replaces one set of unknown initial conditions with another. >>>> >>>> I would also take issue with her suggestion that inflation solves some >>>> problems with the origin of the fluctuations seen in the CMB. Inflation >>>> might provide a framework, but it does not provide an explanation for >>>> these >>>> fluctuations. The fluctuations are built in by hand, and the gaussian >>>> nature of the fluctuations is also built in by hand. So these features of >>>> the CMB are not "explained" by inflation in any sense at all. There >>>> gaussian nature, and the relative magnitude of 10^{-5} are both free >>>> parameters that are set by hand. >>>> >>>> >>> The initial conditions, what ever they were, were flattened out though >>> by inflation. The anisotropy in the CMB is due to details in the field >>> configuration of the scalar field. The theory just provides the action S = >>> ∫d^4x√g(φR + L(φ)), but not the explicit initial conditions or the >>> configuration of the field at reheating. The point though is these details >>> were exponentially attenuated by inflation so their magnitude is small. >>> Estimates of this works out pretty well. >>> >>> LC >>> >> >> I have a different model. Inflation didn't attentuate the initial >> condition. Rather it *preserved* an initial condition of virtually >> perfect uniformity, which was about the one part in 100,000 observed in the >> CMBR. Before inflation began, the universe was tiny, say much less than the >> diameter of a proton. It was so small in comparison to the SoL, that it was >> in thermo equilbrium *before* inflation began. The sudden huge expansion >> preserved the already existing thermo equilibrium. If inflation didn't >> happen, the time of recombination would have occurred much later than >> 380,000 years after the BB, and by that time the original very tiny >> fluctuations would have increased, resulting in relatively large variations >> in the CMBR, much more than one part in 100,000. What I haven't calculated >> -- because I don't know how -- is whether the time duration before >> inflation was long enough, despite the large SoL, for the universe to reach >> an approximate thermo equilbrium of one part in 100,000. AG >> > > For various reasons this will not work. With inflation the cosmological > horizon was 10^{-27}m in radius. The real problem is that without inflation > winding back the cosmic time leads to nonsensical conditions. > > LC >
Why won't it work? What are the nonsensical conditions when the clock is reversed? I didn't claim there is no inflation, so what have the nonsensical conditions have to do with anything I wrote? AG > > >> >>> >>>> >>>> Winding the timeline of the universe back in time based on no >>>>> inflation results in a problem because of high z physics, in particular >>>>> the >>>>> CMB. Without this high vacuum energy and extreme acceleration there is no >>>>> way to get everything in the same region so they causally evolved >>>>> according >>>>> to the same set of initial conditions. In fact before inflation this was >>>>> a >>>>> problem that buggered cosmologies back in the 1960s and 70s. >>>>> >>>> >>>> Perhaps it took a while to realise the importance of initial >>>> conditions...... >>>> >>>> Bruce >>>> >>>> >>> -- 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/ac826987-2d17-4649-8314-8e973dff2f87%40googlegroups.com.
