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* > 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/ab5ead73-8aa3-4ebf-835f-3f5f839eb537%40googlegroups.com.
