On Mon, Dec 24, 2018 at 1:38 AM John Clark <[email protected]> wrote:
> On Sat, Dec 22, 2018 at 11:32 PM Bruce Kellett <[email protected]> > 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 [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
