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 <
>>>> goldenfield...@gmail.com> 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 <
>>>>>> goldenfield...@gmail.com> 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 <agrays...@gmail.com>
>>>>>>>> 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
>
>
>>
>>>
>>>>
>>>> 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
>>>>
>>>>
>>>
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