On Mon, Dec 24, 2018 at 1:38 AM John Clark <johnkcl...@gmail.com> wrote:
> On Sat, Dec 22, 2018 at 11:32 PM Bruce Kellett <bhkellet...@gmail.com> > wrote: > > *> The point is that inflation only solves the problem given certain >> initial conditions. We have no independent knowledge of those initial >> conditions, * > > > From observations I think we do have a little knowledge about what those > initial conditions must have been, they could not have been fractal and > infinitely complex as Penrose postulated because then the universe would > also have started out in a condition of maximum possible entropy and could > not have evolved to be in the much lower entropy state we see today. > > > *so it could well be that the initial condition was that everything was >> always at a uniform temperature,* > > > It's not just temperature, the initial conditions would also be that > spacetime was uniformly flat. Today the observed density of matter/energy > in the universe is very close to what would be needed to achieve overall > spacetime flatness; for this to be true today the early universe must have > been closer than one part in 10^62 to that critical density point. > Coincidence? Maybe, but I doubt it. > > >> > *and there was no need for something, such as inflation, to render the >> CMB uniform everywhere.* > > > So inflation can't fix things if the universe started out with infinite > complexity and entropy, but nothing else could either and yet the universe > we see today is not in a maximum entropy state. And inflation is not needed > if the initial conditions were at a uniform temperature and the mass/energy > density was within one part in 10^62 of the critical point. > Flatness is explained if the unknown parameter k in the FRW solution is set to zero. The the universe is always flat, no need to fine tune. Setting k = 1 or k = -1 is just as fine-tuned or not as k=0. > It would seem to me that if two theories can explain observations then the > one with the simpler initial conditions is the superior. > The trouble is that inflation is not a simple theory. Where does the inflation potential come from? (Do you even know what it is? Why don't we see the inflaton?)The slow roll parameters have to be fine-tuned to a remarkable degree to get agreement with observation, etc, etc. All you have to do without inflation is have smooth initial conditions with k=0 -- very much simpler..... 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 everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
