On Thursday, October 3, 2019 at 5:52:08 PM UTC-5, Alan Grayson wrote: > > > > 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 >
In order to explain it fully would require pumping out a fair amount of general relativity stuff. I am not going there right now --- too tired. If what you say were to work it would have already been proposed and accepted. LC > >> >>> >>>> >>>>> >>>>> 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/55758171-35b3-4b65-b36b-7e2303158765%40googlegroups.com.
