On Saturday, October 5, 2019 at 7:57:59 AM UTC-6, Lawrence Crowell wrote: > > On Saturday, October 5, 2019 at 4:57:10 AM UTC-5, Alan Grayson wrote: >> >> On Friday, October 4, 2019 at 4:57:30 PM UTC-6, Lawrence Crowell wrote: >>> >>> On Friday, October 4, 2019 at 7:32:32 AM UTC-5, Alan Grayson wrote: >>>> >>>> On Friday, October 4, 2019 at 4:50:12 AM UTC-6, Lawrence Crowell wrote: >>>>> >>>>> On Friday, October 4, 2019 at 5:34:42 AM UTC-5, Alan Grayson wrote: >>>>>> >>>>>> On Friday, October 4, 2019 at 3:31:31 AM UTC-6, Lawrence Crowell >>>>>> wrote: >>>>>>> >>>>>>> On Thursday, October 3, 2019 at 8:13:22 PM UTC-5, Alan Grayson wrote: >>>>>>>> >>>>>>>> On Thursday, October 3, 2019 at 7:05:12 PM UTC-6, Lawrence Crowell >>>>>>>> wrote: >>>>>>>>> >>>>>>>>> On Thursday, October 3, 2019 at 8:01:49 PM UTC-5, Lawrence Crowell >>>>>>>>> wrote: >>>>>>>>>> >>>>>>>>>> On Thursday, October 3, 2019 at 6:59:35 PM UTC-5, Bruce wrote: >>>>>>>>>>> >>>>>>>>>>> On Fri, Oct 4, 2019 at 9:54 AM Alan Grayson <[email protected]> >>>>>>>>>>> wrote: >>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> ISTM, that the argument the universe was NOT in thermo >>>>>>>>>>>> equilibrium just before inflation is alleged to have begun, is >>>>>>>>>>>> extremely >>>>>>>>>>>> WEAK. Thus, it's illogical to claim that inflation "smooths out" >>>>>>>>>>>> the >>>>>>>>>>>> alleged NON thermo equiiibrium just before inflation begun. AG >>>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> That is essentially what I said. Lawrence is just replacing one >>>>>>>>>>> set of unknown initial conditions with another, equally >>>>>>>>>>> unjustified, set. >>>>>>>>>>> >>>>>>>>>>> Bruce >>>>>>>>>>> >>>>>>>>>> >>>>>>>>> In below & means δ. I forgot to replace them. >>>>>>>>> >>>>>>>>> LC >>>>>>>>> >>>>>>>>> >>>>>>>>>> >>>>>>>>>> The entropy is S = A/4ℓ_p^2 + quantum corrections, where these >>>>>>>>>> corrections are ~ (&S/&h^a)k^a. Here h^a is tangent to the horizon >>>>>>>>>> and k^a >>>>>>>>>> is normal. This condition coincident on a null surface can appear on >>>>>>>>>> a >>>>>>>>>> quantum extremal surface with null tangent g^s so that (&S/&h^a)k^a >>>>>>>>>> ≥ >>>>>>>>>> (&S/&g^a)k^a by subadditivity. However, this surface occurs inside >>>>>>>>>> the >>>>>>>>>> cosmological horizon. This means there is no equilibriium. >>>>>>>>>> Equilibrium is >>>>>>>>>> only approximated by stretching the horizon out to enormous distance >>>>>>>>>> after >>>>>>>>>> the spatial surface has inflated. >>>>>>>>>> >>>>>>>>>> It is the case that inflation does not tell us the whole story >>>>>>>>>> prior to inflation. So one can say there are equally unknown initial >>>>>>>>>> conditions. However, the details of those are less important as the >>>>>>>>>> spatial >>>>>>>>>> manifold is stretched out. That means inflation does provide at >>>>>>>>>> least a >>>>>>>>>> working system. >>>>>>>>>> >>>>>>>>>> LC >>>>>>>>>> >>>>>>>>> >>>>>>>> Assuming the universe was incredibly tiny prior to inflation, and >>>>>>>> was therefore causally connected, isn't it reasonable to assume that >>>>>>>> it had >>>>>>>> reached thermo equilibrium *prior* to the onset of inflation? AG >>>>>>>> >>>>>>> >>>>>>> Thermal equilibrium is not possible with quantum fields in curved >>>>>>> spacetiome, nor is is likely in quantum gravity. The reason is not too >>>>>>> hard >>>>>>> to see. Suppose you have a black hole in a thermal background with the >>>>>>> same >>>>>>> temperature as its horizon T ~ 1/8M. The black hole has an >>>>>>> equiprobability >>>>>>> of absorbing or emitting a photon with energy δM The temperature then >>>>>>> adjusts as T - δT ~ 1/8(M + δM) or T + δT ~ 1/8(M - δM) and is shifted >>>>>>> away >>>>>>> from thermal equality. This will then enhance the probability the black >>>>>>> hole either then grows by absorbing more photons or by emitting them. >>>>>>> There >>>>>>> is no thermal equilibrium. Quantum gravitation is likely the same, for >>>>>>> the >>>>>>> effective specific heat of event horizons is negative. What I wrote >>>>>>> above >>>>>>> is in effect a more general form of this. >>>>>>> >>>>>>> Now a gemish of particles or a gas can be in thermal equilibrium in >>>>>>> spacetime. >>>>>>> >>>>>> >>>>>> *Doesn't this characterize the universe before inflation began? If >>>>>> not, then what? AG* >>>>>> >>>>> >>>>> No, the large plasma of particles was generated in the post >>>>> inflationary period with reheating or the collapse of the vacuum or >>>>> inflaton. >>>>> >>>>> LC >>>>> >>>> >>>> If not a plasma of particles before inflation, then what was it -- a >>>> soup of photons, or what? Also, although I really don't know much about >>>> BH's, your analysis above depends on a boundary between the BH and what's >>>> beyond it. In the pre-inflation universe there was no internal boundary >>>> within the universe, so I don't see the relevance of the BH analogy. AG >>>> >>> >>> I will write it one more time. Particles and radiation emerged in the >>> observable universe, or this pocket world, with the collapse of the vacuum >>> energy or inflaton by the mass-gap. The drop in vacuum energy produced the >>> matter and radiation around us. >>> >>> LC >>> >> >> OK; no particles or radiation prior to the onseet of inflation. But >> supposing your model is correct, given the incredibly small size of the >> universe as inflation proceeded, wouldn't those particles and radiation, >> once created, have been in thermal equilibrium throughout, supporting my >> model that inflation preserves the thermal equilibrium of the very early >> universe, but doesn't create it (as measured in the CMBR)? I agree with >> Clark (and you?) about flatness and monopoles, but I think he didn't >> understand my reason for thinking the very early universe was in thermal >> equilbrium, and that this state wasn't created, but *preserved* by >> inflation. AG >> > > They came to equilibrium, and what thermal fluctuations that deviated away > from equilibrium were "ironed out" by inflation. >
It's the "ironed out" that I don't understand. If there were some fluctuations, small deviations from thermal equilibrium, why would a sudden expansion attenuate them? It makes more sense to me that the universe was already very close to thermal equilibrium during inflation, and inflation *preserved* this state. BTW, I am not "belaboring" anything here; rather, I am trying to resolve, or possibly modify, a key element of the inflation model. AG > The current state of the universe is such that it emerged from a much > lower state of entropy than what we would otherwise think. This state of > low entropy was available to a causal region that inflated out, and what > fluctuations existed were stretched out and reduced in relative magnitude. > > I fail to see why so many people have trouble with this. It is not a final > answer, for that will require not only quantum gravitation, but a theory of > quantum gravitation that is worked into a fair measure of maturity. > However, inflation does push the barrier of ignorance back a fair degree. > > LC > > >> >>> >>>> >>>>> >>>>>> >>>>>> >>>>>>> That was what was set up with inflation. The whole process of the >>>>>>> early expanding universe is about there being episodes of approximate >>>>>>> thermal equilibrium of particles, such as during the quark-gluon plasma >>>>>>> phase, electroweak period, the QED equilibrium of electrons and photon >>>>>>> or >>>>>>> the plasma phase that ended by producing the CMB. >>>>>>> >>>>>>> To think about physics one has to do a sort of Buddhist middle way. >>>>>>> It is not good to either be too liberal or given to extreme >>>>>>> speculations, >>>>>>> but it is also not good to be overly conservative. >>>>>>> >>>>>>> LC >>>>>>> >>>>>> -- 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/b948e163-d8dc-4b49-8ef7-35aba1fb7a6c%40googlegroups.com.
