Re: CMBR

[Alan Grayson]

On Wednesday, April 8, 2020 at 8:01:40 PM UTC-6, Alan Grayson wrote:
>
>
>
> On Wednesday, April 8, 2020 at 7:52:19 PM UTC-6, Alan Grayson wrote:
>>
>> I've asked this before but can't recall the responses, so bear with me. 
>> At the time of recombination, when H atoms formed, is the CMBR the result 
>> of the fact that the total energy of neutral H is LESS  than that of 
>> protons and electrons existing independently, and that the CMBR is the 
>> energy emitted when H atoms formed? If not, what is the source of the CMBR? 
>> TIA, AG
>>
>
> I think that was my original hypothesis, which is apparently incorrect as 
> it would result in a single emission frequency, not that of a black-body. 
> AG  
>

The confusion, IMO, of what it means to be a "black-body" involves the idea 
that "black" generally means total absorption of incoming radiation, 
implying no emission, whereas the usual example of black-body radiation is 
the* emission* from a small hole in a cavity which is at thermodynamic 
equilibrium.  What seems to be the case, is that incoming radiation in the 
cavity example is totally absorbed -- no reflection whatsoever -- but the 
incoming photons are bounced around the walls of the cavity, possibly 
changing frequency with each impact, with the emitted radiation taking the 
form of the distribution of so-called black-body radiation. This connects 
with the idea that the CMBR is predicted to a black body distribution since 
before recombination, photons were entrapped in the early, foggy universe 
as if they were in a cavity. AG

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Re: CMBR

[Alan Grayson]

On Wednesday, April 8, 2020 at 7:52:19 PM UTC-6, Alan Grayson wrote:
>
> I've asked this before but can't recall the responses, so bear with me. At 
> the time of recombination, when H atoms formed, is the CMBR the result of 
> the fact that the total energy of neutral H is LESS  than that of protons 
> and electrons existing independently, and that the CMBR is the energy 
> emitted when H atoms formed? If not, what is the source of the CMBR? TIA, AG
>

I think that was my original hypothesis, which is apparently incorrect as 
it would result in a single emission frequency, not that of a blackbody. 
AG  

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CMBR

[Alan Grayson]

I've asked this before but can't recall the responses, so bear with me. At 
the time of recombination, when H atoms formed, is the CMBR the result of 
the fact that the total energy of neutral H is LESS  than that of protons 
and electrons existing independently, and that the CMBR is the energy 
emitted when H atoms formed? If not, what is the source of the CMBR? TIA, AG

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Re: CMBR

[agrayson2000]

On Sunday, March 17, 2019 at 2:49:43 AM UTC-6, Bruce wrote:
>
> On Sun, Mar 17, 2019 at 7:38 PM > wrote:
>
>>
>>
>> On Thursday, March 14, 2019 at 8:27:58 PM UTC-6, agrays...@gmail.com 
>> wrote:
>>>
>>> IIUC, the combined mass of an electron and proton is larger than the 
>>> hydrogen atom they form at recombination time. Thus, I would expect a very 
>>> narrow pulse of energy as a result when recombination occurs. This 
>>> apparently being the case, why does the CMBR have a black body distribution 
>>> and not a pulse with a very narrow spread? TIA, AG
>>>
>>
>> Is this a really dumb question and the reason for zero replies; or is it 
>> because no one here has the answer? Or maybe just no interest in another 
>> puzzle? AG
>>
>
> Dumb question. CMB is thermal radiation, not the recombination energy. It 
> reflects the temperature at the time the universe became transparent to 
> radiation of all wavelengths -- because the electron-proton plasma 
> recombined to form less reactive hydrogen.
>
> Bruce 
>

FWIW, the origin of the "dumb question" was my impression, from texts I 
have read, that the CMBR* originated *with recombination, in which case it 
should be totally a function of that recombination. In fact, it is just the 
black body radiation of the universe projected forward in time, with the 
hydrogen absorption lines imposed. Then I made a second error in forgetting 
that hydrogen has a countably infinite set of energy states, not simply a 
single one.  Anyway, now I see my errors, and thank everyone for their 
indulgence. AG

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Re: CMBR

[agrayson2000]

On Monday, March 18, 2019 at 11:36:24 AM UTC-6, Brent wrote:
>
>
>
> On 3/18/2019 2:34 AM, agrays...@gmail.com  wrote: 
> > If that's the case, then there's no visible remnant of the 
> > recombination in the observed CMBR, and what we observe is simply the 
> > cooled BB radiation of pre-combination times. So what does the CMBR 
> > tell us? AG 
>
> It tells us it was hot.  So those lines were smeared out by doppler 
> shifts due the motion of the particles. 
>
> Brent 
>

More important IMO, is that it tells us that the cosmological red shift is 
due to an expanding universe, not, say, to "tired light". AG 

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Re: CMBR

[Lawrence Crowell]

On Monday, March 18, 2019 at 12:36:24 PM UTC-5, Brent wrote:
>
>
>
> On 3/18/2019 2:34 AM, agrays...@gmail.com  wrote: 
> > If that's the case, then there's no visible remnant of the 
> > recombination in the observed CMBR, and what we observe is simply the 
> > cooled BB radiation of pre-combination times. So what does the CMBR 
> > tell us? AG 
>
> It tells us it was hot.  So those lines were smeared out by doppler 
> shifts due the motion of the particles. 
>
> Brent 
>

The spread in a spectral line with a broadening 1/f' - 1/f is red shifted 
as z(1/f' - 1/f) and so spread in frequency is zff'/(f - f'). For f' close 
to f this is large to begin with. Then with the z factor this amplifies 
things. The spread in frequencies spills over the gap.

LC

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Re: CMBR

['Brent Meeker' via Everything List]

On 3/18/2019 2:34 AM, agrayson2...@gmail.com wrote:
If that's the case, then there's no visible remnant of the 
recombination in the observed CMBR, and what we observe is simply the 
cooled BB radiation of pre-combination times. So what does the CMBR 
tell us? AG


It tells us it was hot.  So those lines were smeared out by doppler 
shifts due the motion of the particles.


Brent

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Re: CMBR

[agrayson2000]

On Sunday, March 17, 2019 at 6:17:01 PM UTC-6, Lawrence Crowell wrote:
>
> On Sunday, March 17, 2019 at 1:36:22 PM UTC-6, agrays...@gmail.com wrote:
>>
>>
>>
>> On Sunday, March 17, 2019 at 12:12:58 PM UTC-6, Brent wrote:
>>>
>>>
>>>
>>> On 3/17/2019 4:50 AM, agrays...@gmail.com wrote:
>>>
>>>
>>>
>>> On Sunday, March 17, 2019 at 3:05:14 AM UTC-6, agrays...@gmail.com 
>>> wrote: 
>>>>
>>>>
>>>>
>>>> On Sunday, March 17, 2019 at 2:49:43 AM UTC-6, Bruce wrote: 
>>>>>
>>>>> On Sun, Mar 17, 2019 at 7:38 PM  wrote:
>>>>>
>>>>>>
>>>>>>
>>>>>> On Thursday, March 14, 2019 at 8:27:58 PM UTC-6, agrays...@gmail.com 
>>>>>> wrote: 
>>>>>>>
>>>>>>> IIUC, the combined mass of an electron and proton is larger than the 
>>>>>>> hydrogen atom they form at recombination time. Thus, I would expect a 
>>>>>>> very 
>>>>>>> narrow pulse of energy as a result when recombination occurs. This 
>>>>>>> apparently being the case, why does the CMBR have a black body 
>>>>>>> distribution 
>>>>>>> and not a pulse with a very narrow spread? TIA, AG
>>>>>>>
>>>>>>
>>>>>> Is this a really dumb question and the reason for zero replies; or is 
>>>>>> it because no one here has the answer? Or maybe just no interest in 
>>>>>> another 
>>>>>> puzzle? AG
>>>>>>
>>>>>
>>>>> Dumb question. CMB is thermal radiation, not the recombination energy. 
>>>>> It reflects the temperature at the time the universe became transparent 
>>>>> to 
>>>>> radiation of all wavelengths -- because the electron-proton plasma 
>>>>> recombined to form less reactive hydrogen.
>>>>>
>>>>> Bruce 
>>>>>
>>>>
>>>> But the recombination energy must be part of the mix at recombination 
>>>> time and this is never mentioned in the texts I have read. I suppose this 
>>>> is another dumb question. AG 
>>>>
>>>
>>> What this thread shows is that I don't understand the CMBR. Maybe no one 
>>> does. ISTM that the universe was cooling *prior* to recombination time 
>>> and therefore must have had a thermal spectrum *independent* of the 
>>> recombination. Yet the going assumption, AFAICT, is that the CMBR *comes 
>>> into existence* at recombination time, but is independent of the 
>>> physical recombination which is never included or mentioned as part of the 
>>> observed spectrum.  Can anyone explain what is actually going on in this 
>>> model? TIA, AG
>>>
>>>
>>> Your mistake is assuming that this recombination is one big jump from 
>>> complete dissociation to bound hydrogen atom.  A hydrogen atom has lots of 
>>> energy states and, as the plasma cooled due to expansion, there would be a 
>>> continuous shift of energy from the proton/electron to the gamma rays.
>>>
>>> Brent
>>>
>>
>> In fact, hydrogen has a countably infinite set of energy states, which I 
>> forgot. Is it correct to say that these recombination states form the 
>> thermal signature which is observed (in which case Bruce's explanation is 
>> misleading)? AG  
>>
>
> I am presuming you are raising the prospect of there being absorption 
> lines in the spectrum, just as we see the same with the sun. There were 
> such lines for the hydrogen atom after recombination that would have been 
> visible. However, with red shifting by z = 1100 and spectral broadening 
> they have been smeared out. 
>
> LC
>

If that's the case, then there's no visible remnant of the recombination in 
the observed CMBR, and what we observe is simply the cooled BB radiation of 
pre-combination times. So what does the CMBR tell us? AG  

>
> [image: spectrum of the sun.jpg]
>  
>

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Re: CMBR

[smitra]

See here:

https://academic.oup.com/mnras/article/371/4/1939/1060928

Saibal

On 15-03-2019 03:27, agrayson2...@gmail.com wrote:

IIUC, the combined mass of an electron and proton is larger than the
hydrogen atom they form at recombination time. Thus, I would expect a
very narrow pulse of energy as a result when recombination occurs.
This apparently being the case, why does the CMBR have a black body
distribution and not a pulse with a very narrow spread? TIA, AG

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Re: CMBR

[Bruce Kellett]

On Mon, Mar 18, 2019 at 6:36 AM  wrote:

> On Sunday, March 17, 2019 at 12:12:58 PM UTC-6, Brent wrote:
>>
>> On 3/17/2019 4:50 AM, agrays...@gmail.com wrote:
>>
>> On Sunday, March 17, 2019 at 3:05:14 AM UTC-6, agrays...@gmail.com
>> wrote:
>>>
>>>
>>>
>>> On Sunday, March 17, 2019 at 2:49:43 AM UTC-6, Bruce wrote:
>>>>
>>>> On Sun, Mar 17, 2019 at 7:38 PM  wrote:
>>>>
>>>>>
>>>>>
>>>>> On Thursday, March 14, 2019 at 8:27:58 PM UTC-6, agrays...@gmail.com
>>>>> wrote:
>>>>>>
>>>>>> IIUC, the combined mass of an electron and proton is larger than the
>>>>>> hydrogen atom they form at recombination time. Thus, I would expect a 
>>>>>> very
>>>>>> narrow pulse of energy as a result when recombination occurs. This
>>>>>> apparently being the case, why does the CMBR have a black body 
>>>>>> distribution
>>>>>> and not a pulse with a very narrow spread? TIA, AG
>>>>>>
>>>>>
>>>>> Is this a really dumb question and the reason for zero replies; or is
>>>>> it because no one here has the answer? Or maybe just no interest in 
>>>>> another
>>>>> puzzle? AG
>>>>>
>>>>
>>>> Dumb question. CMB is thermal radiation, not the recombination energy.
>>>> It reflects the temperature at the time the universe became transparent to
>>>> radiation of all wavelengths -- because the electron-proton plasma
>>>> recombined to form less reactive hydrogen.
>>>>
>>>> Bruce
>>>>
>>>
>>> But the recombination energy must be part of the mix at recombination
>>> time and this is never mentioned in the texts I have read. I suppose this
>>> is another dumb question. AG
>>>
>>
>> What this thread shows is that I don't understand the CMBR. Maybe no one
>> does. ISTM that the universe was cooling *prior* to recombination time
>> and therefore must have had a thermal spectrum *independent* of the
>> recombination. Yet the going assumption, AFAICT, is that the CMBR *comes
>> into existence* at recombination time, but is independent of the
>> physical recombination which is never included or mentioned as part of the
>> observed spectrum.  Can anyone explain what is actually going on in this
>> model? TIA, AG
>>
>>
>> Your mistake is assuming that this recombination is one big jump from
>> complete dissociation to bound hydrogen atom.  A hydrogen atom has lots of
>> energy states and, as the plasma cooled due to expansion, there would be a
>> continuous shift of energy from the proton/electron to the gamma rays.
>>
>> Brent
>>
>
> In fact, hydrogen has a countably infinite set of energy states, which I
> forgot. Is it correct to say that these recombination states form the
> thermal signature which is observed (in which case Bruce's explanation is
> misleading)? AG
>

No, that is not a correct thing to say. Recombination occurs when the
average thermal energy of particles in the plasma was below the
dissociation energy of hydrogen, which, as I recall, is around 14 eV. But
the radiation we see as CMB now is the blackbody radiation from this
initial plasma. Energy contributions from the recombination of hydrogen
atoms are present, but just form part of the thermal spectrum -- because
not all recombinations take a proton and an electron directly from the
unbound state to the lowest energy state (14.? eV). There is a range as
electrons cascade down, and many of these transitions are of much lower
energy -- red-shafted to invisibility now.

Bruce

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Re: CMBR

[agrayson2000]

On Sunday, March 17, 2019 at 12:12:58 PM UTC-6, Brent wrote:
>
>
>
> On 3/17/2019 4:50 AM, agrays...@gmail.com  wrote:
>
>
>
> On Sunday, March 17, 2019 at 3:05:14 AM UTC-6, agrays...@gmail.com wrote: 
>>
>>
>>
>> On Sunday, March 17, 2019 at 2:49:43 AM UTC-6, Bruce wrote: 
>>>
>>> On Sun, Mar 17, 2019 at 7:38 PM  wrote:
>>>
>>>>
>>>>
>>>> On Thursday, March 14, 2019 at 8:27:58 PM UTC-6, agrays...@gmail.com 
>>>> wrote: 
>>>>>
>>>>> IIUC, the combined mass of an electron and proton is larger than the 
>>>>> hydrogen atom they form at recombination time. Thus, I would expect a 
>>>>> very 
>>>>> narrow pulse of energy as a result when recombination occurs. This 
>>>>> apparently being the case, why does the CMBR have a black body 
>>>>> distribution 
>>>>> and not a pulse with a very narrow spread? TIA, AG
>>>>>
>>>>
>>>> Is this a really dumb question and the reason for zero replies; or is 
>>>> it because no one here has the answer? Or maybe just no interest in 
>>>> another 
>>>> puzzle? AG
>>>>
>>>
>>> Dumb question. CMB is thermal radiation, not the recombination energy. 
>>> It reflects the temperature at the time the universe became transparent to 
>>> radiation of all wavelengths -- because the electron-proton plasma 
>>> recombined to form less reactive hydrogen.
>>>
>>> Bruce 
>>>
>>
>> But the recombination energy must be part of the mix at recombination 
>> time and this is never mentioned in the texts I have read. I suppose this 
>> is another dumb question. AG 
>>
>
> What this thread shows is that I don't understand the CMBR. Maybe no one 
> does. ISTM that the universe was cooling *prior* to recombination time 
> and therefore must have had a thermal spectrum *independent* of the 
> recombination. Yet the going assumption, AFAICT, is that the CMBR *comes 
> into existence* at recombination time, but is independent of the physical 
> recombination which is never included or mentioned as part of the observed 
> spectrum.  Can anyone explain what is actually going on in this model? TIA, 
> AG
>
>
> Your mistake is assuming that this recombination is one big jump from 
> complete dissociation to bound hydrogen atom.  A hydrogen atom has lots of 
> energy states and, as the plasma cooled due to expansion, there would be a 
> continuous shift of energy from the proton/electron to the gamma rays.
>
> Brent
>

In fact, hydrogen has a countably infinite set of energy states, which I 
forgot. Is it correct to say that these recombination states form the 
thermal signature which is observed (in which case Bruce's explanation is 
misleading)? AG  

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Re: CMBR

['Brent Meeker' via Everything List]

On 3/17/2019 4:50 AM, agrayson2...@gmail.com wrote:



On Sunday, March 17, 2019 at 3:05:14 AM UTC-6, agrays...@gmail.com wrote:



On Sunday, March 17, 2019 at 2:49:43 AM UTC-6, Bruce wrote:

On Sun, Mar 17, 2019 at 7:38 PM  wrote:



On Thursday, March 14, 2019 at 8:27:58 PM UTC-6,
agrays...@gmail.com wrote:

IIUC, the combined mass of an electron and proton is
larger than the hydrogen atom they form at
recombination time. Thus, I would expect a very narrow
pulse of energy as a result when recombination occurs.
This apparently being the case, why does the CMBR have
a black body distribution and not a pulse with a very
narrow spread? TIA, AG


Is this a really dumb question and the reason for zero
replies; or is it because no one here has the answer? Or
maybe just no interest in another puzzle? AG


Dumb question. CMB is thermal radiation, not the recombination
energy. It reflects the temperature at the time the universe
became transparent to radiation of all wavelengths -- because
the electron-proton plasma recombined to form less reactive
hydrogen.

Bruce


But the recombination energy must be part of the mix at
recombination time and this is never mentioned in the texts I have
read. I suppose this is another dumb question. AG


What this thread shows is that I don't understand the CMBR. Maybe no 
one does. ISTM that the universe was cooling *prior* to recombination 
time and therefore must have had a thermal spectrum *independent* of 
the recombination. Yet the going assumption, AFAICT, is that the CMBR 
*comes into existence* at recombination time, but is independent of 
the physical recombination which is never included or mentioned as 
part of the observed spectrum.  Can anyone explain what is actually 
going on in this model? TIA, AG


Your mistake is assuming that this recombination is one big jump from 
complete dissociation to bound hydrogen atom.  A hydrogen atom has lots 
of energy states and, as the plasma cooled due to expansion, there would 
be a continuous shift of energy from the proton/electron to the gamma rays.


Brent

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Re: CMBR

[agrayson2000]

On Sunday, March 17, 2019 at 3:05:14 AM UTC-6, agrays...@gmail.com wrote:
>
>
>
> On Sunday, March 17, 2019 at 2:49:43 AM UTC-6, Bruce wrote:
>>
>> On Sun, Mar 17, 2019 at 7:38 PM  wrote:
>>
>>>
>>>
>>> On Thursday, March 14, 2019 at 8:27:58 PM UTC-6, agrays...@gmail.com 
>>> wrote:
>>>>
>>>> IIUC, the combined mass of an electron and proton is larger than the 
>>>> hydrogen atom they form at recombination time. Thus, I would expect a very 
>>>> narrow pulse of energy as a result when recombination occurs. This 
>>>> apparently being the case, why does the CMBR have a black body 
>>>> distribution 
>>>> and not a pulse with a very narrow spread? TIA, AG
>>>>
>>>
>>> Is this a really dumb question and the reason for zero replies; or is it 
>>> because no one here has the answer? Or maybe just no interest in another 
>>> puzzle? AG
>>>
>>
>> Dumb question. CMB is thermal radiation, not the recombination energy. It 
>> reflects the temperature at the time the universe became transparent to 
>> radiation of all wavelengths -- because the electron-proton plasma 
>> recombined to form less reactive hydrogen.
>>
>> Bruce 
>>
>
> But the recombination energy must be part of the mix at recombination time 
> and this is never mentioned in the texts I have read. I suppose this is 
> another dumb question. AG 
>

What this thread shows is that I don't understand the CMBR. Maybe no one 
does. ISTM that the universe was cooling *prior* to recombination time and 
therefore must have had a thermal spectrum *independent* of the 
recombination. Yet the going assumption, AFAICT, is that the CMBR *comes 
into existence* at recombination time, but is independent of the physical 
recombination which is never included or mentioned as part of the observed 
spectrum.  Can anyone explain what is actually going on in this model? TIA, 
AG

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Re: CMBR

[agrayson2000]

On Sunday, March 17, 2019 at 2:49:43 AM UTC-6, Bruce wrote:
>
> On Sun, Mar 17, 2019 at 7:38 PM > wrote:
>
>>
>>
>> On Thursday, March 14, 2019 at 8:27:58 PM UTC-6, agrays...@gmail.com 
>> wrote:
>>>
>>> IIUC, the combined mass of an electron and proton is larger than the 
>>> hydrogen atom they form at recombination time. Thus, I would expect a very 
>>> narrow pulse of energy as a result when recombination occurs. This 
>>> apparently being the case, why does the CMBR have a black body distribution 
>>> and not a pulse with a very narrow spread? TIA, AG
>>>
>>
>> Is this a really dumb question and the reason for zero replies; or is it 
>> because no one here has the answer? Or maybe just no interest in another 
>> puzzle? AG
>>
>
> Dumb question. CMB is thermal radiation, not the recombination energy. It 
> reflects the temperature at the time the universe became transparent to 
> radiation of all wavelengths -- because the electron-proton plasma 
> recombined to form less reactive hydrogen.
>
> Bruce 
>

But the recombination energy must be part of the mix at recombination time 
and this is never mentioned in the texts I have read. I suppose this is 
another dumb question. AG 

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Re: CMBR

[Bruce Kellett]

On Sun, Mar 17, 2019 at 7:38 PM  wrote:

>
>
> On Thursday, March 14, 2019 at 8:27:58 PM UTC-6, agrays...@gmail.com
> wrote:
>>
>> IIUC, the combined mass of an electron and proton is larger than the
>> hydrogen atom they form at recombination time. Thus, I would expect a very
>> narrow pulse of energy as a result when recombination occurs. This
>> apparently being the case, why does the CMBR have a black body distribution
>> and not a pulse with a very narrow spread? TIA, AG
>>
>
> Is this a really dumb question and the reason for zero replies; or is it
> because no one here has the answer? Or maybe just no interest in another
> puzzle? AG
>

Dumb question. CMB is thermal radiation, not the recombination energy. It
reflects the temperature at the time the universe became transparent to
radiation of all wavelengths -- because the electron-proton plasma
recombined to form less reactive hydrogen.

Bruce

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Re: CMBR

[agrayson2000]

On Thursday, March 14, 2019 at 8:27:58 PM UTC-6, agrays...@gmail.com wrote:
>
> IIUC, the combined mass of an electron and proton is larger than the 
> hydrogen atom they form at recombination time. Thus, I would expect a very 
> narrow pulse of energy as a result when recombination occurs. This 
> apparently being the case, why does the CMBR have a black body distribution 
> and not a pulse with a very narrow spread? TIA, AG
>

Is this a really dumb question and the reason for zero replies; or is it 
because no one here has the answer? Or maybe just no interest in another 
puzzle? AG

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CMBR

[agrayson2000]

IIUC, the combined mass of an electron and proton is larger than the 
hydrogen atom they form at recombination time. Thus, I would expect a very 
narrow pulse of energy as a result when recombination occurs. This 
apparently being the case, why does the CMBR have a black body distribution 
and not a pulse with a very narrow spread? TIA, AG

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Re: CMBR and Horizon Problem

[agrayson2000]

On Tuesday, January 1, 2019 at 6:24:03 PM UTC, John Clark wrote:
>
> On Tue, Jan 1, 2019 at 3:41 AM > wrote:
>  
>
>> *> not all points external to an observer are receding at speed faster 
>> than light. Still, ISTM that inflation just preserves the temperature 
>> distribution which exists when it began,*
>
>
> The idea is before inflation a small volume was able to achieve thermal 
> equilibrium within itself even though the universe was very very young 
> because the volume was so small. But then that small volume started to 
> expand faster than light and exponentially doubled in size at least 100 
> times every 10^-35 seconds, and today that super tiny volume is our entire 
> observable universe. The FTL expansion is why very distant parts of the 
> CMBR are at almost exactly the same temperature even though today they are 
> not causally connected. And the random quantum variations that must have 
> existed in that very tiny volume before inflation started explains why the 
> temperature of the CMBR is *almost* the same everywhere but not exactly so. 
>  
>

*How are the random quantum fluctuations due to the UP related to 
temperature variations? Are you assuming that each different quantum 
measurement of energy corresponds to a different temperature? TIA, AG *

>
>  John K Clark 
>
>
>

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Re: CMBR and Horizon Problem

[agrayson2000]

On Monday, December 31, 2018 at 1:40:22 AM UTC, Lawrence Crowell wrote:
>
> On Saturday, December 22, 2018 at 5:46:18 AM UTC-6, agrays...@gmail.com 
> wrote:
>>
>> If the temperature was non uniform when the BB occurred, if it occurred, 
>> why would a sudden increase in its volume, aka inflation, erase or wash out 
>> those non uniformities? ISTM, it would preserve them. OTOH, if the initial 
>> temperature were uniform, would that obviate the need for inflation, or 
>> would non uniformities tend to become manifest were it not for inflation? 
>> TIA, AG
>>
>
> I wrote the following to a list concerning this video
>
> https://www.youtube.com/watch?v=XBr4GkRnY04
>
> where I found some problems with this video. 
>

*I viewed the video. It is also misleading in the claim that the universe 
can expand FTL. I meant to say that's a misinterpretation of Hubble's Law. 
The universe can expand very slowly, and we can find regions far away which 
recede FTL. It's a purely geometric effect of any global expansion. AG*

I wrote the following below.
>
> We are in an inflationary cosmology now. It is accelerated expansion, but 
> far less than during the inflationary period. If this accelerated expansion 
> is gentle then local regions with matter can gravitationally clump. If the 
> accelerated expansion is huge, as with the inflationary period where it was 
> 10^{100} times what it is now, then matter or fields in any local region 
> can't clump together as they are rendered apart.
>
> I did not at first watch this because of time and the fact that most 
> elementary popularizations do not illuminate things for me. So I did take a 
> look at this, and there are some problems. The presenter is right in saying 
> that space can expand, which is a feature of general relativity where space 
> or spacetime has differential maps or dynamics. The definition of the 
> Hubble sphere and horizon is a bit confusing.
>
> I have to introduce a bit of general relativity to make some sense of 
> this. Relativity, both special for flat spacetime and general, has it 
> absolute invariant quantity the proper interval that is a length measured 
> by a clock on a local frame. This is a Lorentzian version of the distance 
> formula we learn in early college math which in turn is based on 
> Pythagorean theorem. The distance s is 
>
> s^2 = g_{tt}c^2t^2 - sum_{ij}g_{ij}x_ix_j
>
> where for flat spacetime g_{tt} = 1 and g_{ij} = 1 for i = j and 0 
> otherwise. This interval is a time one measures on a clock, and if you are 
> sitting in flat space not moving anywhere at the origin of the frame then s 
> = ct which has the curious meaning that we are all heading into this fourth 
> dimension at the speed of light. 
>
> I will write this metric distance according to an infinitesimal distance 
> ds, where we can integrate this as s' = ∫ds and ds^2 = g_{ab}dx^adx^b, 
> where we sum on the indices a and b (called Einstein convention) and g_{ab} 
> is the metric tensor or matrix which for diagonal entries (1, -1,-1, -1) 
>  the spacetime is flat and globally special relativistic. There is a deep 
> subject of conformal invariance, which gets into considerable depths in 
> complex variables and differential geometry. This idea is that a space or 
> spacetime may be mapped by some function or multiplicative parameter and 
> angle measures remain the same. We may think of this metric as similarly 
> mapped as g_{ab} → Ω^2g_{ab} such that Ω is a type of expansion factor 
> called a conformal factor. This means the invariant interval is 
>
> ds^2 = Ω^2[c^2du^2 - sum_{ij}g_{ij}dx_idx_j]
>
> where now I have written the time variable as u instead to t and in a 
> sense absorbed g_{tt} into this conformal factor. The reason for this is I 
> want to express the du infinitesimal time unit as du = (du/dt)dt, which is 
> just a chain rule of elementary calculus. Sorry, but a bit of mathematics 
> is just vital. Now let me write this du in such a way that du/dt = Ω^{-1} 
> and this conformal factor means the metric interval is
>
> ds^2 = c^2dt^2 - Ω^2 sum_{ij}g_{ij}dx_idx_j.
>
> I now make some isotropy assumptions to make the metric so that g_{ij} = 1 
> for i=j and 0 otherwise. I then make another identification of the 
> conformal factor with the FLRW or de Sitter expansion factor and so I have
>
> ds^2 = c^2dt^2 - cosh(t sqrt{Λ/3c^2}) sum_i dx_i^2 
>
> or
>
> ds^2 = c^2dt^2 - cosh(t sqrt{Λ/3c^2}) (dr^2 + r^2(dθ^2 +sin^2θdφ^2))
>
> where this just expresses the metric of the three dimensional space in 
> spherical coordinates. Here Λ is the infamous cosmological constant. So we 
> see that a de Sitter spacetime is a time parametrized conformal expansion 
> of space that in turn foliates out spacetime. The space or spatial manifold 
> at each instance of time is flat and any two spatial surfaces of 3 
> dimensions at different times are related to each other by this expansion 
> factor. This metric with the spatial manifold restricted to two dimensions 

Re: CMBR and Horizon Problem

[agrayson2000]

On Monday, December 31, 2018 at 1:40:22 AM UTC, Lawrence Crowell wrote:
>
> On Saturday, December 22, 2018 at 5:46:18 AM UTC-6, agrays...@gmail.com 
> wrote:
>>
>> If the temperature was non uniform when the BB occurred, if it occurred, 
>> why would a sudden increase in its volume, aka inflation, erase or wash out 
>> those non uniformities? ISTM, it would preserve them. OTOH, if the initial 
>> temperature were uniform, would that obviate the need for inflation, or 
>> would non uniformities tend to become manifest were it not for inflation? 
>> TIA, AG
>>
>
> I wrote the following to a list concerning this video
>
> https://www.youtube.com/watch?v=XBr4GkRnY04
>
> where I found some problems with this video.
>



I wrote the following below.
>
> We are in an inflationary cosmology now. It is accelerated expansion, but 
> far less than during the inflationary period. If this accelerated expansion 
> is gentle then local regions with matter can gravitationally clump. If the 
> accelerated expansion is huge, as with the inflationary period where it was 
> 10^{100} times what it is now, then matter or fields in any local region 
> can't clump together as they are rendered apart.
>
> I did not at first watch this because of time and the fact that most 
> elementary popularizations do not illuminate things for me. So I did take a 
> look at this, and there are some problems. The presenter is right in saying 
> that space can expand, which is a feature of general relativity where space 
> or spacetime has differential maps or dynamics. The definition of the 
> Hubble sphere and horizon is a bit confusing.
>
> I have to introduce a bit of general relativity to make some sense of 
> this. Relativity, both special for flat spacetime and general, has it 
> absolute invariant quantity the proper interval that is a length measured 
> by a clock on a local frame. This is a Lorentzian version of the distance 
> formula we learn in early college math which in turn is based on 
> Pythagorean theorem. The distance s is 
>
> s^2 = g_{tt}c^2t^2 - sum_{ij}g_{ij}x_ix_j
>
> where for flat spacetime g_{tt} = 1 and g_{ij} = 1 for i = j and 0 
> otherwise. This interval is a time one measures on a clock, and if you are 
> sitting in flat space not moving anywhere at the origin of the frame then s 
> = ct which has the curious meaning that we are all heading into this fourth 
> dimension at the speed of light. 
>
> I will write this metric distance according to an infinitesimal distance 
> ds, where we can integrate this as s' = ∫ds and ds^2 = g_{ab}dx^adx^b, 
> where we sum on the indices a and b (called Einstein convention) and g_{ab} 
> is the metric tensor or matrix which for diagonal entries (1, -1,-1, -1) 
>  the spacetime is flat and globally special relativistic. There is a deep 
> subject of conformal invariance, which gets into considerable depths in 
> complex variables and differential geometry. This idea is that a space or 
> spacetime may be mapped by some function or multiplicative parameter and 
> angle measures remain the same. We may think of this metric as similarly 
> mapped as g_{ab} → Ω^2g_{ab} such that Ω is a type of expansion factor 
> called a conformal factor. This means the invariant interval is 
>
> ds^2 = Ω^2[c^2du^2 - sum_{ij}g_{ij}dx_idx_j]
>
> where now I have written the time variable as u instead to t and in a 
> sense absorbed g_{tt} into this conformal factor. The reason for this is I 
> want to express the du infinitesimal time unit as du = (du/dt)dt, which is 
> just a chain rule of elementary calculus. Sorry, but a bit of mathematics 
> is just vital. Now let me write this du in such a way that du/dt = Ω^{-1} 
> and this conformal factor means the metric interval is
>
> ds^2 = c^2dt^2 - Ω^2 sum_{ij}g_{ij}dx_idx_j.
>
> I now make some isotropy assumptions to make the metric so that g_{ij} = 1 
> for i=j and 0 otherwise. I then make another identification of the 
> conformal factor with the FLRW or de Sitter expansion factor and so I have
>
> ds^2 = c^2dt^2 - cosh(t sqrt{Λ/3c^2}) sum_i dx_i^2 
>
> or
>
> ds^2 = c^2dt^2 - cosh(t sqrt{Λ/3c^2}) (dr^2 + r^2(dθ^2 +sin^2θdφ^2))
>
> where this just expresses the metric of the three dimensional space in 
> spherical coordinates. Here Λ is the infamous cosmological constant. So we 
> see that a de Sitter spacetime is a time parametrized conformal expansion 
> of space that in turn foliates out spacetime. The space or spatial manifold 
> at each instance of time is flat and any two spatial surfaces of 3 
> dimensions at different times are related to each other by this expansion 
> factor. This metric with the spatial manifold restricted to two dimensions 
> is the hyperboloid pictured below
>
> [image: 
> The-comoving-coordinate-system-of-de-Sitter-space-In-solid-red-there-are-the-E-const.png]
>
>
> Now for the expansion of the universe at late times is approximated by 
> cosh(t sqrt{Λ/3}) ≈ exp(t sqrt{Λ/3c^2}). This then segues into a piece I 
> 

Re: CMBR and Horizon Problem

[agrayson2000]

On Tuesday, January 1, 2019 at 6:24:03 PM UTC, John Clark wrote:
>
> On Tue, Jan 1, 2019 at 3:41 AM > wrote:
>  
>
>> *> not all points external to an observer are receding at speed faster 
>> than light. Still, ISTM that inflation just preserves the temperature 
>> distribution which exists when it began,*
>
>
> The idea is before inflation a small volume was able to achieve thermal 
> equilibrium within itself even though the universe was very very young 
> because the volume was so small. But then that small volume started to 
> expand faster than light and exponentially doubled in size at least 100 
> times every 10^-35 seconds, and today that super tiny volume is our entire 
> observable universe. The FTL expansion is why very distant parts of the 
> CMBR are at almost exactly the same temperature even though today they are 
> not causally connected. 
>


But earlier you wrote that without inflation, the temperature anomalies 
would have been washed out anyway. 

Clark > If inflation didn't happen then after 380,000 years those spots of 
slightly higher and lower temperature would no longer exist because they 
would have been washed out by their surroundings ... .

So without inflation, the CMBR would have *more* uniformity in temperature 
than what it was initially. That's why I stated that inflation preserved 
the initial imperfect uniformity in temperature, but wasn't the *cause* of 
the uniformity. AG

And the random quantum variations that must have existed in that very tiny 
> volume before inflation started explains why the temperature of the CMBR is 
> *almost* the same everywhere but not exactly so.  
>
>  John K Clark 
>
>
>

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Re: CMBR and Horizon Problem

[John Clark]

On Tue, Jan 1, 2019 at 3:41 AM  wrote:


> *> not all points external to an observer are receding at speed faster
> than light. Still, ISTM that inflation just preserves the temperature
> distribution which exists when it began,*


The idea is before inflation a small volume was able to achieve thermal
equilibrium within itself even though the universe was very very young
because the volume was so small. But then that small volume started to
expand faster than light and exponentially doubled in size at least 100
times every 10^-35 seconds, and today that super tiny volume is our entire
observable universe. The FTL expansion is why very distant parts of the
CMBR are at almost exactly the same temperature even though today they are
not causally connected. And the random quantum variations that must have
existed in that very tiny volume before inflation started explains why the
temperature of the CMBR is *almost* the same everywhere but not exactly so.


 John K Clark

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Re: CMBR and Horizon Problem

[agrayson2000]

On Tuesday, January 1, 2019 at 8:25:11 AM UTC, agrays...@gmail.com wrote:
>
>
>
> On Monday, December 31, 2018 at 12:43:17 AM UTC, John Clark wrote:
>>
>> On Sat, Dec 29, 2018 at 10:53 PM  wrote:
>>
>> *> Where does the non conserved energy go, specifically the loss of 
>>> energy represented by the cosmological red shift? AG*
>>
>>
>> If it's non-conserved then the energy went into infinite unbounded 
>> homogeneity, that is to say into nothingness. At the cosmological level 
>> under General Relativity energy is not conserved. It's still true that in a 
>> FIXED volume the energy gained or lost within it is equal to the energy 
>> passing through its boundary, but if the total volume of the universe is 
>> not conserved, as it isn't under General Relativity, then energy isn't 
>> either.
>>
>> As Sean Carroll says:
>> "*in general relativity spacetime can give energy to matter, or absorb 
>> it from matter, so that the total energy simply isn’t conserved *"
>>
>> *> are you saying the small temperature fluctuations due to quantum 
>>> effects were *preserved* by inflation, and if it didn't happen those 
>>> fluctuations would be *larger* than what's observed? AG*
>>
>>
>> If inflation didn't happen then after 380,000 years those spots of 
>> slightly higher and lower temperature would no longer exist because they 
>> would have been washed out by their surroundings, but with inflation they 
>> had grown so large there was not enough time for them to come into thermal 
>> equilibrium with their neighbors.
>>
>
> *I don't get it. Without inflation, the universe still expands FTL so 
> other than the local region for an observer, all other regions remain NOT 
> causally connected. All inflation does is preserve the temperature 
> distribution when it begins, almost immediately after the BB. IOW, I don't 
> see how inflation explains the virtually uniform temperature of the CMBR. 
> AG*
>

*Correction: I didn't apply Hubble's law correctly, so not all points 
external to an observer are receding at speed faster than light. Still, 
ISTM that inflation just preserves the temperature distribution which 
exists when it began, So the CMBR will just reflect that original 
temperature distribution and inflation doesn't cause it to be nearly 
uniform. It will be whatever it was when inflation began. AG *

>
>
>> John K Clark 
>>   
>>
>>
>>>

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Re: CMBR and Horizon Problem

[agrayson2000]

On Monday, December 31, 2018 at 12:43:17 AM UTC, John Clark wrote:
>
> On Sat, Dec 29, 2018 at 10:53 PM > 
> wrote:
>
> *> Where does the non conserved energy go, specifically the loss of energy 
>> represented by the cosmological red shift? AG*
>
>
> If it's non-conserved then the energy went into infinite unbounded 
> homogeneity, that is to say into nothingness. At the cosmological level 
> under General Relativity energy is not conserved. It's still true that in a 
> FIXED volume the energy gained or lost within it is equal to the energy 
> passing through its boundary, but if the total volume of the universe is 
> not conserved, as it isn't under General Relativity, then energy isn't 
> either.
>
> As Sean Carroll says:
> "*in general relativity spacetime can give energy to matter, or absorb it 
> from matter, so that the total energy simply isn’t conserved *"
>
> *> are you saying the small temperature fluctuations due to quantum 
>> effects were *preserved* by inflation, and if it didn't happen those 
>> fluctuations would be *larger* than what's observed? AG*
>
>
> If inflation didn't happen then after 380,000 years those spots of 
> slightly higher and lower temperature would no longer exist because they 
> would have been washed out by their surroundings, but with inflation they 
> had grown so large there was not enough time for them to come into thermal 
> equilibrium with their neighbors.
>

*I don't get it. Without inflation, the universe still expands FTL so other 
than the local region for an observer, all other regions remain NOT 
causally connected. All inflation does is preserve the temperature 
distribution when it begins, almost immediately after the BB. IOW, I don't 
see how inflation explains the virtually uniform temperature of the CMBR. 
AG*

>
> John K Clark 
>   
>
>
>>

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Re: CMBR and Horizon Problem

[John Clark]

On Sat, Dec 29, 2018 at 10:53 PM  wrote:

*> Where does the non conserved energy go, specifically the loss of energy
> represented by the cosmological red shift? AG*


If it's non-conserved then the energy went into infinite unbounded
homogeneity, that is to say into nothingness. At the cosmological level
under General Relativity energy is not conserved. It's still true that in a
FIXED volume the energy gained or lost within it is equal to the energy
passing through its boundary, but if the total volume of the universe is
not conserved, as it isn't under General Relativity, then energy isn't
either.

As Sean Carroll says:
"*in general relativity spacetime can give energy to matter, or absorb it
from matter, so that the total energy simply isn’t conserved *"

*> are you saying the small temperature fluctuations due to quantum effects
> were *preserved* by inflation, and if it didn't happen those fluctuations
> would be *larger* than what's observed? AG*


If inflation didn't happen then after 380,000 years those spots of slightly
higher and lower temperature would no longer exist because they would have
been washed out by their surroundings, but with inflation they had grown so
large there was not enough time for them to come into thermal equilibrium
with their neighbors.

John K Clark



>

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Re: CMBR and Horizon Problem

[agrayson2000]

On Saturday, December 29, 2018 at 12:17:34 AM UTC, John Clark wrote:
>
> On Fri, Dec 28, 2018 at 4:53 PM Bruce Kellett  > wrote:
>
> >> If the creation of the inflaton required conditions that existed when 
>>> the universe was 10^-44 seconds old and inflation had decayed away when it 
>>> was 10^-35 seconds old then the particle associated with the inflation 
>>> field would have decayed away too and we wouldn't expect to see it today 
>>> even at places where we can reproduce conditions the universe was in when 
>>> it was 10^-17 seconds old. If it still existed it would still be strongly 
>>> connected to regular matter but we could not detect it but the universe 
>>> could and would still be expanding at an exponential rate and galaxies 
>>> stars and planets would not exist, we couldn't detect it because we 
>>> wouldn't exist either.
>>>
>>
>> *> Very good reasons for saying that no such field or particle exists, or 
>> have ever existed.*
>>
>
> Or has ever existed? How do you figure that?
>
> *> I hope you understand the difference between thermal fluctuations and 
>> quantum fluctuations*
>>
>
> The thermal fluctuations that have been actually observed in the Cosmic 
> Microwave Background Radiation is consistent with them being caused by 
> random quantum fluctuations. Do you have an explanation for these 
> variations in temperature that does not involve random quantum 
> fluctuations?  
>
> > *In GR, energy is not conserved in non-static space-times. *
>>
>
> Yes.
>

*Where does the non conserved energy go, specifically the loss of energy 
represented by the cosmological red shift? AG *

>  
>
>> *> But energy is exactly conserved locally.*
>>
>
> True but Irrelevant. Were talking about the most non-local thing we can 
> observe, the Cosmic Microwave Background Radiation. Before inflation all 
> parts of the CMB were locally connected and reached thermal equilibrium, 
> but even so due to quantum variation you could have found slight 
> differences in temperature if you had a sensitive enough thermometer and 
> looked at a small enough volume.
>

*Before inflation the CMB didn't exist. In any event, are you saying the 
small temperature fluctuations due to quantum effects were *preserved* by 
inflation, and if it didn't happen those fluctuations would be *larger* 
than what's observed? AG*

But then after everything had expanded faster than light for 10^-35 seconds 
> and doubled in size 100 times things that were once causally connected no 
> longer were, that is to say they were no longer local and never would be 
> again. And then after things had expanded for another 380,000 years at the 
> far more sedate pace we see today we'd expect those super tiny spots of 
> slightly higher and lower temperature (2.724K to 2.726 K) would no longer 
> be super tiny, but none of them would be larger than 380,000 light years 
> across, 
> and that's just what we do see.
>
> John K Clark
>
>
>>

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Re: CMBR and Horizon Problem

[John Clark]

On Fri, Dec 28, 2018 at 7:28 PM Bruce Kellett  wrote:

 If the creation of the inflaton required conditions that existed when
 the universe was 10^-44 seconds old and inflation had decayed away when it
 was 10^-35 seconds old then the particle associated with the inflation
 field would have decayed away too and we wouldn't expect to see it today
 even at places where we can reproduce conditions the universe was in when
 it was 10^-17 seconds old. If it still existed it would still be strongly
 connected to regular matter but we could not detect it but the universe
 could and would still be expanding at an exponential rate and galaxies
 stars and planets would not exist, we couldn't detect it because we
 wouldn't exist either.

>>>
>>> *>>> Very good reasons for saying that no such field or particle exists,
>>> or have ever existed.*
>>>
>>
>> >>Or has ever existed? How do you figure that?
>>
>
> *> If they had ever existed, they would couple strongly to ordinary
> matter, and we would see such inflatons now.*
>

Helium-5 was certainly created in the Big Bang  but we don't see any of it
in nature today because it has a half life of 7.6*10^-22 seconds. And
if inflatons
were created in the Big Bang  we wouldn't expect to see them in nature
today because they had a half life of about 10^-35 seconds.


> > *There are no such things as such quantum fluctuations: *
>

Quantum Fluctuation


> >> We are talking about the most non-local thing we can observe, the Cosmic
>> Microwave Background Radiation.Before inflation all parts of the CMB
>> were locally connected and reached thermal equilibrium, but even so due to
>> quantum variation you could have found slight differences in temperature if
>> you had a sensitive enough thermometer and looked at a small enough volume.
>>
>
>  > *Collections of particles in thermal equilibrium still show random
> fluctuations on the smallest scales -- Boltzmann distribution and all that.*
>

It's a bit silly to ignore quantum mechanics and try to use classical
thermodynamics at a time before inflation when things must have been close
to the Planck Temperature of 10^32 degrees Kelvin.

John K Clark

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Re: CMBR and Horizon Problem

[agrayson2000]

On Saturday, December 29, 2018 at 1:23:19 AM UTC, Bruce wrote:
>
> On Sat, Dec 29, 2018 at 12:01 PM > 
> wrote:
>
>> On Saturday, December 29, 2018 at 12:28:58 AM UTC, Bruce wrote:
>>>
>>> On Sat, Dec 29, 2018 at 11:17 AM John Clark  wrote:
>>>
 On Fri, Dec 28, 2018 at 4:53 PM Bruce Kellett  
 wrote:

 >> If the creation of the inflaton required conditions that existed 
>> when the universe was 10^-44 seconds old and inflation had decayed away 
>> when it was 10^-35 seconds old then the particle associated with the 
>> inflation field would have decayed away too and we wouldn't expect to 
>> see 
>> it today even at places where we can reproduce conditions the universe 
>> was 
>> in when it was 10^-17 seconds old. If it still existed it would still be 
>> strongly connected to regular matter but we could not detect it but the 
>> universe could and would still be expanding at an exponential rate and 
>> galaxies stars and planets would not exist, we couldn't detect it 
>> because we wouldn't exist either.
>>
>
> *> Very good reasons for saying that no such field or particle exists, 
> or have ever existed.*
>

 Or has ever existed? How do you figure that?

>>>
>>> If they had ever existed, they would couple strongly to ordinary matter, 
>>> and we would see such inflatons now. We don't, which is a very good reason 
>>> for saying that they do not exist -- now or ever.
>>>

 *> I hope you understand the difference between thermal fluctuations 
> and quantum fluctuations*
>

 The thermal fluctuations that have been actually observed in the Cosmic 
 Microwave Background Radiation is consistent with them being caused by 
 random quantum fluctuations. Do you have an explanation for these 
 variations in temperature that does not involve random quantum 
 fluctuations? 

>>>
>>> There are no such things as such quantum fluctuations: such fluctuations 
>>> would be local, and violate energy conservation. 
>>>
>>
>>
>> *If you measure the energy of a region repeatedly, the measurements will 
>> vary due to the UP. How is this a violation of energy conservation? It 
>> would be if it were explained by "borrowing" of energy for short times, but 
>> these measurements in fact vary, so IMO it's not a violation of energy 
>> conservation unless one appeals to the fallacious explanation of 
>> "borrowing". Moreover, how can these variations, or fluctuations in energy 
>> be independent of temperature fluctuations as you seem to suggest? AG*
>>
>
> Variations between the results of different measurements are OK because 
> that merely reflects  a superposition of different energy states. 
> Fluctuations absent repeated measurements are not OK. Thermal fluctuations 
> are just the result of the distribution of different energies between 
> particles in a gas or the like.
>

*If you ignore the non detection of the inflaton particle, and in reference 
to my recent argument, why don't you see inflation as a plausible 
explanation for the flatness of the observable universe? AG  *

>
> Bruce
>

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Re: CMBR and Horizon Problem

[Bruce Kellett]

On Sat, Dec 29, 2018 at 12:01 PM  wrote:

> On Saturday, December 29, 2018 at 12:28:58 AM UTC, Bruce wrote:
>>
>> On Sat, Dec 29, 2018 at 11:17 AM John Clark  wrote:
>>
>>> On Fri, Dec 28, 2018 at 4:53 PM Bruce Kellett 
>>> wrote:
>>>
>>> >> If the creation of the inflaton required conditions that existed
> when the universe was 10^-44 seconds old and inflation had decayed away
> when it was 10^-35 seconds old then the particle associated with the
> inflation field would have decayed away too and we wouldn't expect to see
> it today even at places where we can reproduce conditions the universe was
> in when it was 10^-17 seconds old. If it still existed it would still be
> strongly connected to regular matter but we could not detect it but the
> universe could and would still be expanding at an exponential rate and
> galaxies stars and planets would not exist, we couldn't detect it
> because we wouldn't exist either.
>

 *> Very good reasons for saying that no such field or particle exists,
 or have ever existed.*

>>>
>>> Or has ever existed? How do you figure that?
>>>
>>
>> If they had ever existed, they would couple strongly to ordinary matter,
>> and we would see such inflatons now. We don't, which is a very good reason
>> for saying that they do not exist -- now or ever.
>>
>>>
>>> *> I hope you understand the difference between thermal fluctuations and
 quantum fluctuations*

>>>
>>> The thermal fluctuations that have been actually observed in the Cosmic
>>> Microwave Background Radiation is consistent with them being caused by
>>> random quantum fluctuations. Do you have an explanation for these
>>> variations in temperature that does not involve random quantum
>>> fluctuations?
>>>
>>
>> There are no such things as such quantum fluctuations: such fluctuations
>> would be local, and violate energy conservation.
>>
>
>
> *If you measure the energy of a region repeatedly, the measurements will
> vary due to the UP. How is this a violation of energy conservation? It
> would be if it were explained by "borrowing" of energy for short times, but
> these measurements in fact vary, so IMO it's not a violation of energy
> conservation unless one appeals to the fallacious explanation of
> "borrowing". Moreover, how can these variations, or fluctuations in energy
> be independent of temperature fluctuations as you seem to suggest? AG*
>

Variations between the results of different measurements are OK because
that merely reflects  a superposition of different energy states.
Fluctuations absent repeated measurements are not OK. Thermal fluctuations
are just the result of the distribution of different energies between
particles in a gas or the like.

Bruce

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Re: CMBR and Horizon Problem

[agrayson2000]

On Saturday, December 29, 2018 at 12:28:58 AM UTC, Bruce wrote:
>
> On Sat, Dec 29, 2018 at 11:17 AM John Clark  > wrote:
>
>> On Fri, Dec 28, 2018 at 4:53 PM Bruce Kellett > > wrote:
>>
>> >> If the creation of the inflaton required conditions that existed when 
 the universe was 10^-44 seconds old and inflation had decayed away when it 
 was 10^-35 seconds old then the particle associated with the inflation 
 field would have decayed away too and we wouldn't expect to see it today 
 even at places where we can reproduce conditions the universe was in when 
 it was 10^-17 seconds old. If it still existed it would still be strongly 
 connected to regular matter but we could not detect it but the universe 
 could and would still be expanding at an exponential rate and galaxies 
 stars and planets would not exist, we couldn't detect it because we 
 wouldn't exist either.

>>>
>>> *> Very good reasons for saying that no such field or particle exists, 
>>> or have ever existed.*
>>>
>>
>> Or has ever existed? How do you figure that?
>>
>
> If they had ever existed, they would couple strongly to ordinary matter, 
> and we would see such inflatons now. We don't, which is a very good reason 
> for saying that they do not exist -- now or ever.
>
>>
>> *> I hope you understand the difference between thermal fluctuations and 
>>> quantum fluctuations*
>>>
>>
>> The thermal fluctuations that have been actually observed in the Cosmic 
>> Microwave Background Radiation is consistent with them being caused by 
>> random quantum fluctuations. Do you have an explanation for these 
>> variations in temperature that does not involve random quantum 
>> fluctuations? 
>>
>
> There are no such things as such quantum fluctuations: such fluctuations 
> would be local, and violate energy conservation. 
>


*If you measure the energy of a region repeatedly, the measurements will 
vary due to the UP. How is this a violation of energy conservation? It 
would be if it were explained by "borrowing" of energy for short times, but 
these measurements in fact vary, so IMO it's not a violation of energy 
conservation unless one appeals to the fallacious explanation of 
"borrowing". Moreover, how can these variations, or fluctuations in energy 
be independent of temperature fluctuations as you seem to suggest? AG*

*Incidentally, I hope you understand that when I refer to you as "the 
Oracle from Australia", it's in fact complimentary; a jocular compliment 
recognized by those with a sardonic sense of humor. AG*

*> But energy is exactly conserved locally.*
>

True but Irrelevant. Were talking about the most non-local thing we can 
observe, the Cosmic Microwave Background Radiation. Before inflation all 
parts of the CMB were locally connected and reached thermal equilibrium, 
but even so due to quantum variation you could have found slight 
differences in temperature if you had a sensitive enough thermometer and 
looked at a small enough volume.

>
> But you have just described seeing thermal fluctuations. Collections of 
> particles in thermal equilibrium still show random fluctuations on the 
> smallest scales -- Boltzmann distribution and all that.
>
> Bruce
>  
>
>> But then after everything had expanded faster than light for 10^-35 
>> seconds and doubled in size 100 times things that were once causally 
>> connected no longer were, that is to say they were no longer local and 
>> never would be again. And then after things had expanded for another 
>> 380,000 years at the far more sedate pace we see today we'd expect those 
>> super tiny spots of slightly higher and lower temperature (2.724K to 2.726 
>> K) would no longer be super tiny, but none of them would be larger than 
>> 380,000 light years across, and that's just what we do see.
>>
>> John K Clark
>>
>

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Re: CMBR and Horizon Problem

[Bruce Kellett]

On Sat, Dec 29, 2018 at 11:17 AM John Clark  wrote:

> On Fri, Dec 28, 2018 at 4:53 PM Bruce Kellett 
> wrote:
>
> >> If the creation of the inflaton required conditions that existed when
>>> the universe was 10^-44 seconds old and inflation had decayed away when it
>>> was 10^-35 seconds old then the particle associated with the inflation
>>> field would have decayed away too and we wouldn't expect to see it today
>>> even at places where we can reproduce conditions the universe was in when
>>> it was 10^-17 seconds old. If it still existed it would still be strongly
>>> connected to regular matter but we could not detect it but the universe
>>> could and would still be expanding at an exponential rate and galaxies
>>> stars and planets would not exist, we couldn't detect it because we
>>> wouldn't exist either.
>>>
>>
>> *> Very good reasons for saying that no such field or particle exists, or
>> have ever existed.*
>>
>
> Or has ever existed? How do you figure that?
>

If they had ever existed, they would couple strongly to ordinary matter,
and we would see such inflatons now. We don't, which is a very good reason
for saying that they do not exist -- now or ever.

>
> *> I hope you understand the difference between thermal fluctuations and
>> quantum fluctuations*
>>
>
> The thermal fluctuations that have been actually observed in the Cosmic
> Microwave Background Radiation is consistent with them being caused by
> random quantum fluctuations. Do you have an explanation for these
> variations in temperature that does not involve random quantum
> fluctuations?
>

There are no such things as such quantum fluctuations: such fluctuations
would be local, and violate energy conservation. The fluctuations in the
CMB are thermal, and were always so.


> > *In GR, energy is not conserved in non-static space-times. *
>>
>
> Yes.
>
>
>> *> But energy is exactly conserved locally.*
>>
>
> True but Irrelevant. Were talking about the most non-local thing we can
> observe, the Cosmic Microwave Background Radiation. Before inflation all
> parts of the CMB were locally connected and reached thermal equilibrium,
> but even so due to quantum variation you could have found slight
> differences in temperature if you had a sensitive enough thermometer and
> looked at a small enough volume.
>

But you have just described seeing thermal fluctuations. Collections of
particles in thermal equilibrium still show random fluctuations on the
smallest scales -- Boltzmann distribution and all that.

Bruce


> But then after everything had expanded faster than light for 10^-35
> seconds and doubled in size 100 times things that were once causally
> connected no longer were, that is to say they were no longer local and
> never would be again. And then after things had expanded for another
> 380,000 years at the far more sedate pace we see today we'd expect those
> super tiny spots of slightly higher and lower temperature (2.724K to 2.726
> K) would no longer be super tiny, but none of them would be larger than
> 380,000 light years across, and that's just what we do see.
>
> John K Clark
>

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Re: CMBR and Horizon Problem

[John Clark]

On Fri, Dec 28, 2018 at 4:53 PM Bruce Kellett  wrote:

>> If the creation of the inflaton required conditions that existed when
>> the universe was 10^-44 seconds old and inflation had decayed away when it
>> was 10^-35 seconds old then the particle associated with the inflation
>> field would have decayed away too and we wouldn't expect to see it today
>> even at places where we can reproduce conditions the universe was in when
>> it was 10^-17 seconds old. If it still existed it would still be strongly
>> connected to regular matter but we could not detect it but the universe
>> could and would still be expanding at an exponential rate and galaxies
>> stars and planets would not exist, we couldn't detect it because we
>> wouldn't exist either.
>>
>
> *> Very good reasons for saying that no such field or particle exists, or
> have ever existed.*
>

Or has ever existed? How do you figure that?

*> I hope you understand the difference between thermal fluctuations and
> quantum fluctuations*
>

The thermal fluctuations that have been actually observed in the Cosmic
Microwave Background Radiation is consistent with them being caused by
random quantum fluctuations. Do you have an explanation for these
variations in temperature that does not involve random quantum
fluctuations?

> *In GR, energy is not conserved in non-static space-times. *
>

Yes.


> *> But energy is exactly conserved locally.*
>

True but Irrelevant. Were talking about the most non-local thing we can
observe, the Cosmic Microwave Background Radiation. Before inflation all
parts of the CMB were locally connected and reached thermal equilibrium,
but even so due to quantum variation you could have found slight
differences in temperature if you had a sensitive enough thermometer and
looked at a small enough volume. But then after everything had expanded
faster than light for 10^-35 seconds and doubled in size 100 times things
that were once causally connected no longer were, that is to say they were
no longer local and never would be again. And then after things had
expanded for another 380,000 years at the far more sedate pace we see today
we'd expect those super tiny spots of slightly higher and lower temperature
(2.724K to 2.726 K) would no longer be super tiny, but none of them would
be larger than 380,000 light years across, and that's just what we do see.

John K Clark


>

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Re: CMBR and Horizon Problem

[Bruce Kellett]

On Sat, Dec 29, 2018 at 2:06 AM John Clark  wrote:

> On Fri, Dec 28, 2018 at 5:14 AM Bruce Kellett 
> wrote:
>
> > Why has the inflation not been seen at LHC?

>>>
>>> >> The LHC just went offline, when it comes back online after 2 years
>>> of upgrades it should reach energies close to 15 TeV which corresponds to a
>>> temperature of 10^17 Kelvin, and that is the temperature the entire
>>> universe was in when it was about 10^-17 seconds old. But inflation was
>>> over by the time the universe was 10^-35 seconds old. To inflation the
>>> universe was already ancient when it was 10^-17 seconds old.
>>>
>>
>> *> I meant to write that the "inflaton", the particle associated with the
>> inflation field, would have been seen at LHC since it must couple strongly
>> to normal matter, *
>>
>
> If the creation of the inflaton required conditions that existed when the
> universe was 10^-44 seconds old and inflation had decayed away when it was
> 10^-35 seconds old then the particle associated with the inflation field
> would have decayed away too and we wouldn't expect to see it today even at
> places where we can reproduce conditions the universe was in when it was
> 10^-17 seconds old. If it still existed it would still be strongly
> connected to regular matter but we could not detect it but the universe
> could and would still be expanding at an exponential rate and galaxies
> stars and planets would not exist, we couldn't detect it because we
> wouldn't exist either.
>

Very good reasons for saying that no such field or particle exists, or have
ever existed.


> *> Getting density fluctuations from quantum mechanics would violate
>> energy conservation.*
>>
>
> If there were no density fluctuations in a gas you could know both the
> position and velocity of every particle in it and that would most certainly
> violate the laws of quantum mechanics.
>

I hope you understand the difference between thermal fluctuations and
quantum fluctuations


> And we've had experimental confirmation for nearly a century that at the
> cosmological scale energy is not conserved. The expansion of the universe
> causes all photons to be redshifted and lose energy, a clear violation of
> energy conservation. And there are theoretical reasons for thinking so too.
> Noether's theorem says for every symmetry in physics there is a
> corresponding conservation law, so if the laws of physics don't change with
> time then energy is conserved. But General Relativity says the space a
> particle is moving through* can* change with time so energy is *not*
> conserved. If spacetime is curved the energy associated with a point in it
> doesn't even have a unique definition.
>

In GR, energy is not conserved in non-static space-times. But energy is
exactly conserved locally. Again, study the difference between these
situations.

Bruce

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Re: CMBR and Horizon Problem

[agrayson2000]

On Friday, December 28, 2018 at 10:14:13 AM UTC, Bruce wrote:
>
> On Tue, Dec 25, 2018 at 10:52 AM John Clark  > wrote:
>
>> On Mon, Dec 24, 2018 at 4:35 PM Bruce Kellett > > wrote:
>>
>> > *You seem to be convinced by inflation theory. *
>>>
>>
>> No I'm just playing devil's advocate. I'm not convinced it's right I'm 
>> just not convinced it's dead wrong as you seem to be.
>>
>
> I think the many problem with inflationary theory are too easily 
> overlooked.
>  
>
>>
>> *> Why has the inflation not been seen at LHC?*
>>>
>>
>> The LHC just went offline, when it comes back online after 2 years of 
>> upgrades it should reach energies close to 15 TeV which corresponds to a 
>> temperature of 10^17 Kelvin, and that is the temperature the entire 
>> universe was in when it was about 10^-17 seconds old. But inflation was 
>> over by the time the universe was 10^-35 seconds old. To inflation the 
>> universe was already ancient when it was 10^-17 seconds old.
>>
>
> I meant to write that the "inflaton", the particle associated with the 
> inflation field, would have been seen at LHC since it must couple strongly 
> to normal matter, but Google's autocorrect got the better of me, and 
> correct "inflaton" to "inflation". Reach big bang temperatures at the LHC 
> is not the issue here.
>
>  
>
>> This may be related to the fact that no particle accelerator has found 
>> anything surprising in 50 years; but telescopes have, they've revealed new 
>> physics to us.
>>  
>>
>>> *> At the end of the inflationary period, the temperature was absolute 
>>> zero everywhere -- no fluctuations.*
>>>
>>
>> If something was at absolute zero it would violate the third law of 
>> thermodynamics. It would also violate quantum mechanics because you'd know 
>> exactly what the velocity of a particle was (zero) and therefore its 
>> position would not be meaningful because division by zero is not defined. 
>>
>
> Inflation is a semiclassical theory, and the field is treated classically, 
> except when people want to introduce fluctuations. But they forget that 
> there are no such things as quantum fluctuations -- there are only 
> different results obtained from repeated measurement of the same state. 
>

*How is getting different results from repeated measurements different from 
"fluctuations"? AG*
 

> Getting density fluctuations from quantum mechanics would violate energy 
> conservation.
>

*Where does the loss of energy go when we see cosmological red shifting? AG* 

>
> Bruce
>
>>
>>

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Re: CMBR and Horizon Problem

[John Clark]

On Fri, Dec 28, 2018 at 5:14 AM Bruce Kellett  wrote:

> Why has the inflation not been seen at LHC?
>>>
>>
>> >> The LHC just went offline, when it comes back online after 2 years of
>> upgrades it should reach energies close to 15 TeV which corresponds to a
>> temperature of 10^17 Kelvin, and that is the temperature the entire
>> universe was in when it was about 10^-17 seconds old. But inflation was
>> over by the time the universe was 10^-35 seconds old. To inflation the
>> universe was already ancient when it was 10^-17 seconds old.
>>
>
> *> I meant to write that the "inflaton", the particle associated with the
> inflation field, would have been seen at LHC since it must couple strongly
> to normal matter, *
>

If the creation of the inflaton required conditions that existed when the
universe was 10^-44 seconds old and inflation had decayed away when it was
10^-35 seconds old then the particle associated with the inflation field
would have decayed away too and we wouldn't expect to see it today even at
places where we can reproduce conditions the universe was in when it was
10^-17 seconds old. If it still existed it would still be strongly
connected to regular matter but we could not detect it but the universe
could and would still be expanding at an exponential rate and galaxies
stars and planets would not exist, we couldn't detect it because we
wouldn't exist either.

> *> Getting density fluctuations from quantum mechanics would violate
> energy conservation.*
>

If there were no density fluctuations in a gas you could know both the
position and velocity of every particle in it and that would most certainly
violate the laws of quantum mechanics.  And we've had experimental
confirmation for nearly a century that at the cosmological scale energy is
not conserved. The expansion of the universe causes all photons to be
redshifted and lose energy, a clear violation of energy conservation. And
there are theoretical reasons for thinking so too. Noether's theorem says
for every symmetry in physics there is a corresponding conservation law, so
if the laws of physics don't change with time then energy is conserved. But
General Relativity says the space a particle is moving through* can* change
with time so energy is *not* conserved. If spacetime is curved the energy
associated with a point in it doesn't even have a unique definition.

John K Clark

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Re: CMBR and Horizon Problem

[Bruce Kellett]

On Tue, Dec 25, 2018 at 10:52 AM John Clark  wrote:

> On Mon, Dec 24, 2018 at 4:35 PM Bruce Kellett 
> wrote:
>
> > *You seem to be convinced by inflation theory. *
>>
>
> No I'm just playing devil's advocate. I'm not convinced it's right I'm
> just not convinced it's dead wrong as you seem to be.
>

I think the many problem with inflationary theory are too easily overlooked.


>
> *> Why has the inflation not been seen at LHC?*
>>
>
> The LHC just went offline, when it comes back online after 2 years of
> upgrades it should reach energies close to 15 TeV which corresponds to a
> temperature of 10^17 Kelvin, and that is the temperature the entire
> universe was in when it was about 10^-17 seconds old. But inflation was
> over by the time the universe was 10^-35 seconds old. To inflation the
> universe was already ancient when it was 10^-17 seconds old.
>

I meant to write that the "inflaton", the particle associated with the
inflation field, would have been seen at LHC since it must couple strongly
to normal matter, but Google's autocorrect got the better of me, and
correct "inflaton" to "inflation". Reach big bang temperatures at the LHC
is not the issue here.



> This may be related to the fact that no particle accelerator has found
> anything surprising in 50 years; but telescopes have, they've revealed new
> physics to us.
>
>
>> *> At the end of the inflationary period, the temperature was absolute
>> zero everywhere -- no fluctuations.*
>>
>
> If something was at absolute zero it would violate the third law of
> thermodynamics. It would also violate quantum mechanics because you'd know
> exactly what the velocity of a particle was (zero) and therefore its
> position would not be meaningful because division by zero is not defined.
>

Inflation is a semiclassical theory, and the field is treated classically,
except when people want to introduce fluctuations. But they forget that
there are no such things as quantum fluctuations -- there are only
different results obtained from repeated measurement of the same state.
Getting density fluctuations from quantum mechanics would violate energy
conservation.

Bruce

>
>

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Re: CMBR and Horizon Problem

[agrayson2000]

On Thursday, December 27, 2018 at 4:43:23 AM UTC, agrays...@gmail.com wrote:
>
>
>
> On Wednesday, December 26, 2018 at 3:30:58 AM UTC, agrays...@gmail.com 
> wrote:
>>
>>
>>
>> On Wednesday, December 26, 2018 at 2:37:59 AM UTC, Brent wrote:
>>>
>>>
>>>
>>> On 12/25/2018 4:42 PM, agrays...@gmail.com wrote:
>>>
>>>
>>>
>>> On Tuesday, December 25, 2018 at 11:26:14 PM UTC, Brent wrote: 



 On 12/25/2018 8:01 AM, agrays...@gmail.com wrote:



 On Tuesday, December 25, 2018 at 1:16:53 PM UTC, John Clark wrote: 
>
> On Mon, Dec 24, 2018 at 3:21 PM  wrote:
>
> >> You can never prove that any physical quantity is exactly zero, 
>>> but we do know from observations of the cosmic microwave background 
>>> radiation that if the universe is curved at all it is by less than one 
>>> part 
>>> in 100,000.
>>>
>>  
>
> *> Agreed. However, IMO the observed universe cannot be flat with 
>> exactly zero curvature (which I refer to as "mathematically flat) since 
>> that would imply infinite volume *
>>
>
> If information can't travel faster than light then by definition the 
> radius of the spherical volume of the universe you can observe can't be 
> larger than the age of the universe in years times a light year. 
>  
>
>> *> **which contradicts its finite age.*
>>
>
> There is no reason spacetime couldn't extend a finite distance into 
> the past but an infinite distance into the future. 
>

 *The observable universe could continue to expand forever, but it 
 always has a finite radius. We have no information about the unobserved 
 part, so it could be any size, maybe even tiny. AG*


 All of those inferences are based on the universe obeying Friedman's 
 equations, i.e. Einstein's equations for a  homogeneous, isotropic 
 universe.  So they are inconsistent with the unobserved part of the 
 universe obeying some other conditions.  Whether there is a solution with 
 the observable patch being different from the unobservable part is an open 
 question.  If you find one, publish it.  But you can't just assume that 
 because there's an unobserved part that it could be anything.

>>>
>>> *If we don't know anything about the unobservable part of the universe, 
>>> it could obey any conditions; maybe consistent with the Friedman's 
>>> equations, maybe not. I was just saying we can't assume anything. AG*
>>>
>>>
>>> And I'm saying you can't say the observable part of the universe 
>>> satisfies the Friedman equations and the rest of can be anything.  That the 
>>> rest of the universe is constrained by what the observable part is like is 
>>> a consequence of Einstein's equations.  Could Einstein's equations be 
>>> wrong?  Sure they could, but they've passed every test, so applying them is 
>>> not an assumption.
>>>
>>
>> *I concur. Using the Cosmological Principle, one would expect the 
>> unobservable region to obey the same or similar laws as the observable 
>> region. What's your view of whether inflation solves the flatness problem? 
>> TIA, AG*
>>
>
> *Bruce doesn't buy it and I am not sure why. Far be it from me to disagree 
> with the Oracle from Australia, but I figure the curvature of the visible 
> region is well know (although I don't have a clue how it's measured), and I 
> believe there's some nominal reasonable rate of expansion based on 
> Friedman's equations (although I haven't a clue WHAT it is). Therefore, 
> based on these values and my state of belief, it must be the case that the 
> observable region is way too flat for an expansion that spanned 13.8 
> billion years at the assumed rate. Therefore again, it seems reasonable 
> that inflation could account for this discrepancy. Why is this view 
> simplistic to the point of being wrong, as Bruce would have it? TIA, AG*
>

*As for the temperature very close to the BB, I would expect it to be 
uniform given the small size (as Clark claims), or possibly random due to 
quantum effects. If the latter, then maybe inflation is required to smooth 
out the fluctuations. But I don't have a feel for which initial condition 
is more plausible. Opinions welcome. AG*

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Re: CMBR and Horizon Problem

[agrayson2000]

On Wednesday, December 26, 2018 at 3:30:58 AM UTC, agrays...@gmail.com 
wrote:
>
>
>
> On Wednesday, December 26, 2018 at 2:37:59 AM UTC, Brent wrote:
>>
>>
>>
>> On 12/25/2018 4:42 PM, agrays...@gmail.com wrote:
>>
>>
>>
>> On Tuesday, December 25, 2018 at 11:26:14 PM UTC, Brent wrote: 
>>>
>>>
>>>
>>> On 12/25/2018 8:01 AM, agrays...@gmail.com wrote:
>>>
>>>
>>>
>>> On Tuesday, December 25, 2018 at 1:16:53 PM UTC, John Clark wrote: 

 On Mon, Dec 24, 2018 at 3:21 PM  wrote:

 >> You can never prove that any physical quantity is exactly zero, but 
>> we do know from observations of the cosmic microwave background 
>> radiation 
>> that if the universe is curved at all it is by less than one part in 
>> 100,000.
>>
>  

 *> Agreed. However, IMO the observed universe cannot be flat with 
> exactly zero curvature (which I refer to as "mathematically flat) since 
> that would imply infinite volume *
>

 If information can't travel faster than light then by definition the 
 radius of the spherical volume of the universe you can observe can't be 
 larger than the age of the universe in years times a light year. 
  

> *> **which contradicts its finite age.*
>

 There is no reason spacetime couldn't extend a finite distance into the 
 past but an infinite distance into the future. 

>>>
>>> *The observable universe could continue to expand forever, but it always 
>>> has a finite radius. We have no information about the unobserved part, so 
>>> it could be any size, maybe even tiny. AG*
>>>
>>>
>>> All of those inferences are based on the universe obeying Friedman's 
>>> equations, i.e. Einstein's equations for a  homogeneous, isotropic 
>>> universe.  So they are inconsistent with the unobserved part of the 
>>> universe obeying some other conditions.  Whether there is a solution with 
>>> the observable patch being different from the unobservable part is an open 
>>> question.  If you find one, publish it.  But you can't just assume that 
>>> because there's an unobserved part that it could be anything.
>>>
>>
>> *If we don't know anything about the unobservable part of the universe, 
>> it could obey any conditions; maybe consistent with the Friedman's 
>> equations, maybe not. I was just saying we can't assume anything. AG*
>>
>>
>> And I'm saying you can't say the observable part of the universe 
>> satisfies the Friedman equations and the rest of can be anything.  That the 
>> rest of the universe is constrained by what the observable part is like is 
>> a consequence of Einstein's equations.  Could Einstein's equations be 
>> wrong?  Sure they could, but they've passed every test, so applying them is 
>> not an assumption.
>>
>
> *I concur. Using the Cosmological Principle, one would expect the 
> unobservable region to obey the same or similar laws as the observable 
> region. What's your view of whether inflation solves the flatness problem? 
> TIA, AG*
>

*Bruce doesn't buy it and I am not sure why. Far be it from me to disagree 
with the Oracle from Australia, but I figure the curvature of the visible 
region is well know (although I don't have a clue how it's measured), and I 
believe there's some nominal reasonable rate of expansion based on 
Friedman's equations (although I haven't a clue with it is). Therefore, 
based on these values and my state of belief, it must be the case that the 
observable region is way too flat for an expansion that spanned 13.8 
billion years at the assumed rate. Therefore again, it seems reasonable 
that inflation could account for this discrepancy. Why is this view 
simplistic to the point of being wrong, as Bruce would have it? TIA, AG*

>
>

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Re: CMBR and Horizon Problem

[agrayson2000]

On Wednesday, December 26, 2018 at 2:37:59 AM UTC, Brent wrote:
>
>
>
> On 12/25/2018 4:42 PM, agrays...@gmail.com  wrote:
>
>
>
> On Tuesday, December 25, 2018 at 11:26:14 PM UTC, Brent wrote: 
>>
>>
>>
>> On 12/25/2018 8:01 AM, agrays...@gmail.com wrote:
>>
>>
>>
>> On Tuesday, December 25, 2018 at 1:16:53 PM UTC, John Clark wrote: 
>>>
>>> On Mon, Dec 24, 2018 at 3:21 PM  wrote:
>>>
>>> >> You can never prove that any physical quantity is exactly zero, but 
> we do know from observations of the cosmic microwave background radiation 
> that if the universe is curved at all it is by less than one part in 
> 100,000.
>
  
>>>
>>> *> Agreed. However, IMO the observed universe cannot be flat with 
 exactly zero curvature (which I refer to as "mathematically flat) since 
 that would imply infinite volume *

>>>
>>> If information can't travel faster than light then by definition the 
>>> radius of the spherical volume of the universe you can observe can't be 
>>> larger than the age of the universe in years times a light year. 
>>>  
>>>
 *> **which contradicts its finite age.*

>>>
>>> There is no reason spacetime couldn't extend a finite distance into the 
>>> past but an infinite distance into the future. 
>>>
>>
>> *The observable universe could continue to expand forever, but it always 
>> has a finite radius. We have no information about the unobserved part, so 
>> it could be any size, maybe even tiny. AG*
>>
>>
>> All of those inferences are based on the universe obeying Friedman's 
>> equations, i.e. Einstein's equations for a  homogeneous, isotropic 
>> universe.  So they are inconsistent with the unobserved part of the 
>> universe obeying some other conditions.  Whether there is a solution with 
>> the observable patch being different from the unobservable part is an open 
>> question.  If you find one, publish it.  But you can't just assume that 
>> because there's an unobserved part that it could be anything.
>>
>
> *If we don't know anything about the unobservable part of the universe, it 
> could obey any conditions; maybe consistent with the Friedman's equations, 
> maybe not. I was just saying we can't assume anything. AG*
>
>
> And I'm saying you can't say the observable part of the universe satisfies 
> the Friedman equations and the rest of can be anything.  That the rest of 
> the universe is constrained by what the observable part is like is a 
> consequence of Einstein's equations.  Could Einstein's equations be wrong?  
> Sure they could, but they've passed every test, so applying them is not an 
> assumption.
>

*I concur. Using the Cosmological Principle, one would expect the 
unobservable region to obey the same or similar laws as the observable 
region. What's your view of whether inflation solves the flatness problem? 
TIA, AG*

>
> Brent
>

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Re: CMBR and Horizon Problem

[Brent Meeker]

On 12/25/2018 4:42 PM, agrayson2...@gmail.com wrote:



On Tuesday, December 25, 2018 at 11:26:14 PM UTC, Brent wrote:



On 12/25/2018 8:01 AM, agrays...@gmail.com  wrote:



On Tuesday, December 25, 2018 at 1:16:53 PM UTC, John Clark wrote:

On Mon, Dec 24, 2018 at 3:21 PM  wrote:

>> You can never prove that any physical quantity is
exactly zero, but we do know from observations of the
cosmic microwave background radiation that if the
universe is curved at all it is by less than one part
in 100,000.

/> Agreed. However, IMO the observed universe cannot be
flat with exactly zero curvature (which I refer to as
"mathematically flat) since that would imply infinite
volume /


If information can't travel faster than light then by
definition the radius of the spherical volume of the universe
you can observe can't be larger than the age of the universe
in years times a light year.

*> */which contradicts its finite age./


There is no reason spacetime couldn't extend a finite
distance into the past but an infinite distance into the future.


*The observable universe could continue to expand forever, but it
always has a finite radius. We have no information about the
unobserved part, so it could be any size, maybe even tiny. AG*


All of those inferences are based on the universe obeying
Friedman's equations, i.e. Einstein's equations for a homogeneous,
isotropic universe.  So they are inconsistent with the unobserved
part of the universe obeying some other conditions.  Whether there
is a solution with the observable patch being different from the
unobservable part is an open question.  If you find one, publish
it.  But you can't just assume that because there's an unobserved
part that it could be anything.


*If we don't know anything about the unobservable part of the 
universe, it could obey any conditions; maybe consistent with the 
Friedman's equations, maybe not. I was just saying we can't assume 
anything. AG*


And I'm saying you can't say the observable part of the universe 
satisfies the Friedman equations and the rest of can be anything. That 
the rest of the universe is constrained by what the observable part is 
like is a consequence of Einstein's equations.  Could Einstein's 
equations be wrong?  Sure they could, but they've passed every test, so 
applying them is not an assumption.


Brent

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Re: CMBR and Horizon Problem

[agrayson2000]

On Tuesday, December 25, 2018 at 11:26:14 PM UTC, Brent wrote:
>
>
>
> On 12/25/2018 8:01 AM, agrays...@gmail.com  wrote:
>
>
>
> On Tuesday, December 25, 2018 at 1:16:53 PM UTC, John Clark wrote: 
>>
>> On Mon, Dec 24, 2018 at 3:21 PM  wrote:
>>
>> >> You can never prove that any physical quantity is exactly zero, but 
 we do know from observations of the cosmic microwave background radiation 
 that if the universe is curved at all it is by less than one part in 
 100,000.

>>>  
>>
>> *> Agreed. However, IMO the observed universe cannot be flat with exactly 
>>> zero curvature (which I refer to as "mathematically flat) since that would 
>>> imply infinite volume *
>>>
>>
>> If information can't travel faster than light then by definition the 
>> radius of the spherical volume of the universe you can observe can't be 
>> larger than the age of the universe in years times a light year. 
>>  
>>
>>> *> **which contradicts its finite age.*
>>>
>>
>> There is no reason spacetime couldn't extend a finite distance into the 
>> past but an infinite distance into the future. 
>>
>
> *The observable universe could continue to expand forever, but it always 
> has a finite radius. We have no information about the unobserved part, so 
> it could be any size, maybe even tiny. AG*
>
>
> All of those inferences are based on the universe obeying Friedman's 
> equations, i.e. Einstein's equations for a  homogeneous, isotropic 
> universe.  So they are inconsistent with the unobserved part of the 
> universe obeying some other conditions.  Whether there is a solution with 
> the observable patch being different from the unobservable part is an open 
> question.  If you find one, publish it.  But you can't just assume that 
> because there's an unobserved part that it could be anything.
>

*If we don't know anything about the unobservable part of the universe, it 
could obey any conditions; maybe consistent with the Friedman's equations, 
maybe not. I was just saying we can't assume anything. AG*

>
> Brent
>

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Re: CMBR and Horizon Problem

[Brent Meeker]

On 12/25/2018 8:01 AM, agrayson2...@gmail.com wrote:



On Tuesday, December 25, 2018 at 1:16:53 PM UTC, John Clark wrote:

On Mon, Dec 24, 2018 at 3:21 PM > wrote:

>> You can never prove that any physical quantity is exactly
zero, but we do know from observations of the cosmic
microwave background radiation that if the universe is
curved at all it is by less than one part in 100,000.

/> Agreed. However, IMO the observed universe cannot be flat
with exactly zero curvature (which I refer to as
"mathematically flat) since that would imply infinite volume /


If information can't travel faster than light then by definition
the radius of the spherical volume of the universe you can observe
can't be larger than the age of the universe in years times a
light year.

*> */which contradicts its finite age./


There is no reason spacetime couldn't extend a finite distance
into the past but an infinite distance into the future.


*The observable universe could continue to expand forever, but it 
always has a finite radius. We have no information about the 
unobserved part, so it could be any size, maybe even tiny. AG*


All of those inferences are based on the universe obeying Friedman's 
equations, i.e. Einstein's equations for a  homogeneous, isotropic 
universe.  So they are inconsistent with the unobserved part of the 
universe obeying some other conditions.  Whether there is a solution 
with the observable patch being different from the unobservable part is 
an open question.  If you find one, publish it.  But you can't just 
assume that because there's an unobserved part that it could be anything.


Brent

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Re: CMBR and Horizon Problem

[agrayson2000]

On Tuesday, December 25, 2018 at 1:16:53 PM UTC, John Clark wrote:
>
> On Mon, Dec 24, 2018 at 3:21 PM > wrote:
>
> >> You can never prove that any physical quantity is exactly zero, but we 
>>> do know from observations of the cosmic microwave background radiation that 
>>> if the universe is curved at all it is by less than one part in 100,000.
>>>
>>  
>
> *> Agreed. However, IMO the observed universe cannot be flat with exactly 
>> zero curvature (which I refer to as "mathematically flat) since that would 
>> imply infinite volume *
>>
>
> If information can't travel faster than light then by definition the 
> radius of the spherical volume of the universe you can observe can't be 
> larger than the age of the universe in years times a light year.
>  
>
>> *> **which contradicts its finite age.*
>>
>
> There is no reason spacetime couldn't extend a finite distance into the 
> past but an infinite distance into the future. 
>

*The observable universe could continue to expand forever, but it always 
has a finite radius. We have no information about the unobserved part, so 
it could be any size, maybe even tiny. AG*

>
>  John K Clark
>
>

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Re: CMBR and Horizon Problem

[John Clark]

On Mon, Dec 24, 2018 at 3:21 PM  wrote:

>> You can never prove that any physical quantity is exactly zero, but we
>> do know from observations of the cosmic microwave background radiation that
>> if the universe is curved at all it is by less than one part in 100,000.
>>
>

*> Agreed. However, IMO the observed universe cannot be flat with exactly
> zero curvature (which I refer to as "mathematically flat) since that would
> imply infinite volume *
>

If information can't travel faster than light then by definition the radius
of the spherical volume of the universe you can observe can't be larger than
the age of the universe in years times a light year.


> *> **which contradicts its finite age.*
>

There is no reason spacetime couldn't extend a finite distance into the
past but an infinite distance into the future.

 John K Clark

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Re: CMBR and Horizon Problem

[agrayson2000]

On Tuesday, December 25, 2018 at 7:05:10 AM UTC, Jason wrote:
>
>
>
> On Tue, Dec 25, 2018 at 1:53 AM > wrote:
>
>>
>>
>> On Tuesday, December 25, 2018 at 5:57:35 AM UTC, Jason wrote:
>>>
>>>
>>>
>>> On Mon, Dec 24, 2018 at 11:27 PM  wrote:
>>>


 On Tuesday, December 25, 2018 at 2:13:46 AM UTC, agrays...@gmail.com 
 wrote:
>
>
>
> On Tuesday, December 25, 2018 at 12:35:24 AM UTC, Jason wrote:
>>
>>
>>
>> On Mon, Dec 24, 2018 at 6:28 PM  wrote:
>>
>>>
>>>
>>> On Monday, December 24, 2018 at 9:47:52 PM UTC, Jason wrote:



 On Mon, Dec 24, 2018 at 4:04 PM  wrote:

>
>
> On Monday, December 24, 2018 at 8:25:11 PM UTC, 
> agrays...@gmail.com wrote:
>>
>>
>>
>> On Monday, December 24, 2018 at 6:40:03 AM UTC, Brent wrote:
>>>
>>>
>>>
>>> On 12/23/2018 8:22 PM, agrays...@gmail.com wrote:
>>>
>>>
>>>
>>> On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote: 



 On 12/23/2018 4:47 PM, agrays...@gmail.com wrote:

 *If by "flat", you mean mathematically flat, like a plane 
 extending infinitely in all directions, as opposed to 
 asymptotically flat 
 like a huge and expanding sphere,  you have to reconcile an 
 infinitesimally 
 tiny universe at the time of the BB, and simultaneously an 
 infinitely large 
 universe extending infinitely in all directions. AG*


 All that's "infinitesimally tiny" is the visible universe.  You 
 must know that the Friedmann equation just defines the dynamics of 
 a scale 
 factor, not a size.

>>>
>>> *Are you claiming the visible universe at the BB was 
>>> infinitesimally tiny, but the non visible part was infinitely large 
>>> (mathematically flat), or huge (asymptotically flat)? AG *
>>>
>>>
>>> Right.  Although we can't be sure whether it is actually flat or 
>>> just very big.
>>>
>>> Brent
>>>
>>
>> *OK. Agreed. We seemed to disagree on this in the past, but maybe 
>> we miscommunicated. AG*
>>
>
> Here's what Ned Wright wrote. 
>
> Is the Universe really infinite or just really big?
>
> We have observations that say that the radius of curvature of the 
> Universe is bigger than 70 billion light years. But the observations 
> allow 
> for either a positive or negative curvature, and this range includes 
> the 
> flat Universe with infinite radius of curvature. The negatively 
> curved 
> space is also infinite in volume even though it is curved. So we know 
> empirically that the volume of the Universe is more than 20 times 
> bigger 
> than volume of the observable Universe. Since we can only look at 
> small 
> piece of an object that has a large radius of curvature, it looks 
> flat. The 
> simplest mathematical model for computing the observed properties of 
> the 
> Universe is then flat Euclidean space. This model is infinite, but 
> what we 
> know about the Universe is that it is really big 
> .
>
>
> 
>
> *It is misleading. He's referring to the VISIBLE universe and 
> concludes it might be infinite in spatial extent. Impossible due to 
> its 
> finite age. I wrote him about this, but never received a reply.  AG*
>
>
>
 It's only impossible if you believe the believe the big bang 
 occurred only at a point, rather than everywhere.

 Consider that every point in space sees everything else around it 
 flying away from it, such that if you rewound time, everything would 
 return 
 to a single point centered at that location. But this is true for 
 every 
 point in space, so the implication is that the BigBang didn't happen 
 at one 
 particular location long in the past, but at every point, including 
 the 
 period at the end of this sentence.

>>>
>>> *You seem inclined to extreme hypotheses for which there is no data. 
>>> AG *
>>>


>> This is the default "standard" model used used by cosmologists, it's 
>> called the concordance model, or the Lambda-CDM model. There is 
>> significant 
>> data for it.
>>
>
> *I don't 

Re: CMBR and Horizon Problem

[Jason Resch]

On Tue, Dec 25, 2018 at 1:53 AM  wrote:

>
>
> On Tuesday, December 25, 2018 at 5:57:35 AM UTC, Jason wrote:
>>
>>
>>
>> On Mon, Dec 24, 2018 at 11:27 PM  wrote:
>>
>>>
>>>
>>> On Tuesday, December 25, 2018 at 2:13:46 AM UTC, agrays...@gmail.com
>>> wrote:



 On Tuesday, December 25, 2018 at 12:35:24 AM UTC, Jason wrote:
>
>
>
> On Mon, Dec 24, 2018 at 6:28 PM  wrote:
>
>>
>>
>> On Monday, December 24, 2018 at 9:47:52 PM UTC, Jason wrote:
>>>
>>>
>>>
>>> On Mon, Dec 24, 2018 at 4:04 PM  wrote:
>>>


 On Monday, December 24, 2018 at 8:25:11 PM UTC, agrays...@gmail.com
 wrote:
>
>
>
> On Monday, December 24, 2018 at 6:40:03 AM UTC, Brent wrote:
>>
>>
>>
>> On 12/23/2018 8:22 PM, agrays...@gmail.com wrote:
>>
>>
>>
>> On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote:
>>>
>>>
>>>
>>> On 12/23/2018 4:47 PM, agrays...@gmail.com wrote:
>>>
>>> *If by "flat", you mean mathematically flat, like a plane
>>> extending infinitely in all directions, as opposed to 
>>> asymptotically flat
>>> like a huge and expanding sphere,  you have to reconcile an 
>>> infinitesimally
>>> tiny universe at the time of the BB, and simultaneously an 
>>> infinitely large
>>> universe extending infinitely in all directions. AG*
>>>
>>>
>>> All that's "infinitesimally tiny" is the visible universe.  You
>>> must know that the Friedmann equation just defines the dynamics of 
>>> a scale
>>> factor, not a size.
>>>
>>
>> *Are you claiming the visible universe at the BB was
>> infinitesimally tiny, but the non visible part was infinitely large
>> (mathematically flat), or huge (asymptotically flat)? AG *
>>
>>
>> Right.  Although we can't be sure whether it is actually flat or
>> just very big.
>>
>> Brent
>>
>
> *OK. Agreed. We seemed to disagree on this in the past, but maybe
> we miscommunicated. AG*
>

 Here's what Ned Wright wrote.

 Is the Universe really infinite or just really big?

 We have observations that say that the radius of curvature of the
 Universe is bigger than 70 billion light years. But the observations 
 allow
 for either a positive or negative curvature, and this range includes 
 the
 flat Universe with infinite radius of curvature. The negatively curved
 space is also infinite in volume even though it is curved. So we know
 empirically that the volume of the Universe is more than 20 times 
 bigger
 than volume of the observable Universe. Since we can only look at small
 piece of an object that has a large radius of curvature, it looks 
 flat. The
 simplest mathematical model for computing the observed properties of 
 the
 Universe is then flat Euclidean space. This model is infinite, but 
 what we
 know about the Universe is that it is really big
 .


 

 *It is misleading. He's referring to the VISIBLE universe and
 concludes it might be infinite in spatial extent. Impossible due to its
 finite age. I wrote him about this, but never received a reply.  AG*



>>> It's only impossible if you believe the believe the big bang
>>> occurred only at a point, rather than everywhere.
>>>
>>> Consider that every point in space sees everything else around it
>>> flying away from it, such that if you rewound time, everything would 
>>> return
>>> to a single point centered at that location. But this is true for every
>>> point in space, so the implication is that the BigBang didn't happen at 
>>> one
>>> particular location long in the past, but at every point, including the
>>> period at the end of this sentence.
>>>
>>
>> *You seem inclined to extreme hypotheses for which there is no data.
>> AG *
>>
>>>
>>>
> This is the default "standard" model used used by cosmologists, it's
> called the concordance model, or the Lambda-CDM model. There is 
> significant
> data for it.
>

 *I don't believe it. AG *

>>>
>>> *I mean I don't believe your interpretation of the Concordance model. AG
>>> *
>>>


>> http://www.universeadventure.org/big_bang/expand-balance.htm
>>
>
> *When the movie is played in reverse, all points converge to a single
> point. This is for the observable 

Re: CMBR and Horizon Problem

[agrayson2000]

On Tuesday, December 25, 2018 at 6:53:28 AM UTC, agrays...@gmail.com wrote:
>
>
>
> On Tuesday, December 25, 2018 at 5:57:35 AM UTC, Jason wrote:
>>
>>
>>
>> On Mon, Dec 24, 2018 at 11:27 PM  wrote:
>>
>>>
>>>
>>> On Tuesday, December 25, 2018 at 2:13:46 AM UTC, agrays...@gmail.com 
>>> wrote:



 On Tuesday, December 25, 2018 at 12:35:24 AM UTC, Jason wrote:
>
>
>
> On Mon, Dec 24, 2018 at 6:28 PM  wrote:
>
>>
>>
>> On Monday, December 24, 2018 at 9:47:52 PM UTC, Jason wrote:
>>>
>>>
>>>
>>> On Mon, Dec 24, 2018 at 4:04 PM  wrote:
>>>


 On Monday, December 24, 2018 at 8:25:11 PM UTC, agrays...@gmail.com 
 wrote:
>
>
>
> On Monday, December 24, 2018 at 6:40:03 AM UTC, Brent wrote:
>>
>>
>>
>> On 12/23/2018 8:22 PM, agrays...@gmail.com wrote:
>>
>>
>>
>> On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote: 
>>>
>>>
>>>
>>> On 12/23/2018 4:47 PM, agrays...@gmail.com wrote:
>>>
>>> *If by "flat", you mean mathematically flat, like a plane 
>>> extending infinitely in all directions, as opposed to 
>>> asymptotically flat 
>>> like a huge and expanding sphere,  you have to reconcile an 
>>> infinitesimally 
>>> tiny universe at the time of the BB, and simultaneously an 
>>> infinitely large 
>>> universe extending infinitely in all directions. AG*
>>>
>>>
>>> All that's "infinitesimally tiny" is the visible universe.  You 
>>> must know that the Friedmann equation just defines the dynamics of 
>>> a scale 
>>> factor, not a size.
>>>
>>
>> *Are you claiming the visible universe at the BB was 
>> infinitesimally tiny, but the non visible part was infinitely large 
>> (mathematically flat), or huge (asymptotically flat)? AG *
>>
>>
>> Right.  Although we can't be sure whether it is actually flat or 
>> just very big.
>>
>> Brent
>>
>
> *OK. Agreed. We seemed to disagree on this in the past, but maybe 
> we miscommunicated. AG*
>

 Here's what Ned Wright wrote. 

 Is the Universe really infinite or just really big?

 We have observations that say that the radius of curvature of the 
 Universe is bigger than 70 billion light years. But the observations 
 allow 
 for either a positive or negative curvature, and this range includes 
 the 
 flat Universe with infinite radius of curvature. The negatively curved 
 space is also infinite in volume even though it is curved. So we know 
 empirically that the volume of the Universe is more than 20 times 
 bigger 
 than volume of the observable Universe. Since we can only look at 
 small 
 piece of an object that has a large radius of curvature, it looks 
 flat. The 
 simplest mathematical model for computing the observed properties of 
 the 
 Universe is then flat Euclidean space. This model is infinite, but 
 what we 
 know about the Universe is that it is really big 
 .


 

 *It is misleading. He's referring to the VISIBLE universe and 
 concludes it might be infinite in spatial extent. Impossible due to 
 its 
 finite age. I wrote him about this, but never received a reply.  AG*



>>> It's only impossible if you believe the believe the big bang 
>>> occurred only at a point, rather than everywhere.
>>>
>>> Consider that every point in space sees everything else around it 
>>> flying away from it, such that if you rewound time, everything would 
>>> return 
>>> to a single point centered at that location. But this is true for every 
>>> point in space, so the implication is that the BigBang didn't happen at 
>>> one 
>>> particular location long in the past, but at every point, including the 
>>> period at the end of this sentence.
>>>
>>
>> *You seem inclined to extreme hypotheses for which there is no data. 
>> AG *
>>
>>>
>>>
> This is the default "standard" model used used by cosmologists, it's 
> called the concordance model, or the Lambda-CDM model. There is 
> significant 
> data for it.
>

 *I don't believe it. AG *

>>>
>>> *I mean I don't believe your interpretation of the Concordance model. AG 
>>> *
>>>


>> http://www.universeadventure.org/big_bang/expand-balance.htm
>>
>
> *When the movie 

Re: CMBR and Horizon Problem

[agrayson2000]

On Tuesday, December 25, 2018 at 5:57:35 AM UTC, Jason wrote:
>
>
>
> On Mon, Dec 24, 2018 at 11:27 PM > 
> wrote:
>
>>
>>
>> On Tuesday, December 25, 2018 at 2:13:46 AM UTC, agrays...@gmail.com 
>> wrote:
>>>
>>>
>>>
>>> On Tuesday, December 25, 2018 at 12:35:24 AM UTC, Jason wrote:



 On Mon, Dec 24, 2018 at 6:28 PM  wrote:

>
>
> On Monday, December 24, 2018 at 9:47:52 PM UTC, Jason wrote:
>>
>>
>>
>> On Mon, Dec 24, 2018 at 4:04 PM  wrote:
>>
>>>
>>>
>>> On Monday, December 24, 2018 at 8:25:11 PM UTC, agrays...@gmail.com 
>>> wrote:



 On Monday, December 24, 2018 at 6:40:03 AM UTC, Brent wrote:
>
>
>
> On 12/23/2018 8:22 PM, agrays...@gmail.com wrote:
>
>
>
> On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote: 
>>
>>
>>
>> On 12/23/2018 4:47 PM, agrays...@gmail.com wrote:
>>
>> *If by "flat", you mean mathematically flat, like a plane 
>> extending infinitely in all directions, as opposed to asymptotically 
>> flat 
>> like a huge and expanding sphere,  you have to reconcile an 
>> infinitesimally 
>> tiny universe at the time of the BB, and simultaneously an 
>> infinitely large 
>> universe extending infinitely in all directions. AG*
>>
>>
>> All that's "infinitesimally tiny" is the visible universe.  You 
>> must know that the Friedmann equation just defines the dynamics of a 
>> scale 
>> factor, not a size.
>>
>
> *Are you claiming the visible universe at the BB was 
> infinitesimally tiny, but the non visible part was infinitely large 
> (mathematically flat), or huge (asymptotically flat)? AG *
>
>
> Right.  Although we can't be sure whether it is actually flat or 
> just very big.
>
> Brent
>

 *OK. Agreed. We seemed to disagree on this in the past, but maybe 
 we miscommunicated. AG*

>>>
>>> Here's what Ned Wright wrote. 
>>>
>>> Is the Universe really infinite or just really big?
>>>
>>> We have observations that say that the radius of curvature of the 
>>> Universe is bigger than 70 billion light years. But the observations 
>>> allow 
>>> for either a positive or negative curvature, and this range includes 
>>> the 
>>> flat Universe with infinite radius of curvature. The negatively curved 
>>> space is also infinite in volume even though it is curved. So we know 
>>> empirically that the volume of the Universe is more than 20 times 
>>> bigger 
>>> than volume of the observable Universe. Since we can only look at small 
>>> piece of an object that has a large radius of curvature, it looks flat. 
>>> The 
>>> simplest mathematical model for computing the observed properties of 
>>> the 
>>> Universe is then flat Euclidean space. This model is infinite, but what 
>>> we 
>>> know about the Universe is that it is really big 
>>> .
>>>
>>>
>>> 
>>>
>>> *It is misleading. He's referring to the VISIBLE universe and 
>>> concludes it might be infinite in spatial extent. Impossible due to its 
>>> finite age. I wrote him about this, but never received a reply.  AG*
>>>
>>>
>>>
>> It's only impossible if you believe the believe the big bang occurred 
>> only at a point, rather than everywhere.
>>
>> Consider that every point in space sees everything else around it 
>> flying away from it, such that if you rewound time, everything would 
>> return 
>> to a single point centered at that location. But this is true for every 
>> point in space, so the implication is that the BigBang didn't happen at 
>> one 
>> particular location long in the past, but at every point, including the 
>> period at the end of this sentence.
>>
>
> *You seem inclined to extreme hypotheses for which there is no data. 
> AG *
>
>>
>>
 This is the default "standard" model used used by cosmologists, it's 
 called the concordance model, or the Lambda-CDM model. There is 
 significant 
 data for it.

>>>
>>> *I don't believe it. AG *
>>>
>>
>> *I mean I don't believe your interpretation of the Concordance model. AG *
>>
>>>
>>>
> http://www.universeadventure.org/big_bang/expand-balance.htm
>

*When the movie is played in reverse, all points converge to a single 
point. This is for the observable universe, which is finite in spatial 
extent. It can't be infinite if the expansion has been proceeding for 
finite time. Outside the observable region, it could 

Re: CMBR and Horizon Problem

[Brent Meeker]

On 12/24/2018 3:34 PM, agrayson2...@gmail.com wrote:



On Monday, December 24, 2018 at 10:42:10 PM UTC, Brent wrote:



On 12/24/2018 1:04 PM, agrays...@gmail.com  wrote:



On Monday, December 24, 2018 at 8:25:11 PM UTC,
agrays...@gmail.com wrote:



On Monday, December 24, 2018 at 6:40:03 AM UTC, Brent wrote:



On 12/23/2018 8:22 PM, agrays...@gmail.com wrote:



On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent
wrote:



On 12/23/2018 4:47 PM, agrays...@gmail.com wrote:

*If by "flat", you mean mathematically flat, like a
plane extending infinitely in all directions, as
opposed to asymptotically flat like a huge and
expanding sphere,  you have to reconcile an
infinitesimally tiny universe at the time of the
BB, and simultaneously an infinitely large universe
extending infinitely in all directions. AG*


All that's "infinitesimally tiny" is the visible
universe.  You must know that the Friedmann equation
just defines the dynamics of a scale factor, not a size.


*Are you claiming the visible universe at the BB was
infinitesimally tiny, but the non visible part was
infinitely large (mathematically flat), or huge
(asymptotically flat)? AG *


Right.  Although we can't be sure whether it is actually
flat or just very big.

Brent


*OK. Agreed. We seemed to disagree on this in the past, but
maybe we miscommunicated. AG*


Here's what Ned Wright wrote.


Is the Universe really infinite or just really big?

We have observations that say that the radius of curvature of the
Universe is bigger than 70 billion light years. But the
observations allow for either a positive or negative curvature,
and this range includes the flat Universe with infinite radius of
curvature. The negatively curved space is also infinite in volume
even though it is curved. So we know empirically that the volume
of the Universe is more than 20 times bigger than volume of the
observable Universe. Since we can only look at small piece of an
object that has a large radius of curvature, it looks flat. The
simplest mathematical model for computing the observed properties
of the Universe is then flat Euclidean space. This model is
infinite, but what we know about the Universe is that it isreally
big .




*
*
*It is misleading. He's referring to the VISIBLE universe and
concludes it might be infinite in spatial extent. Impossible due
to its finite age. I wrote him about this, but never received a
reply. AG*


Why don't you look at his web tutorial.  He does not conclude the
/*visible*/ universe might be infinite.


*From the statement above, due to poor use of language, it seems he 
concludes the visible universe might be infinite.  I didn't see that 
corrected anywhere in his tutorial, but I didn't read it in its 
entirety. AG*



http://www.astro.ucla.edu/~wright/cosmo_03.htm

Brent

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Re: CMBR and Horizon Problem

[Jason Resch]

On Mon, Dec 24, 2018 at 11:27 PM  wrote:

>
>
> On Tuesday, December 25, 2018 at 2:13:46 AM UTC, agrays...@gmail.com
> wrote:
>>
>>
>>
>> On Tuesday, December 25, 2018 at 12:35:24 AM UTC, Jason wrote:
>>>
>>>
>>>
>>> On Mon, Dec 24, 2018 at 6:28 PM  wrote:
>>>


 On Monday, December 24, 2018 at 9:47:52 PM UTC, Jason wrote:
>
>
>
> On Mon, Dec 24, 2018 at 4:04 PM  wrote:
>
>>
>>
>> On Monday, December 24, 2018 at 8:25:11 PM UTC, agrays...@gmail.com
>> wrote:
>>>
>>>
>>>
>>> On Monday, December 24, 2018 at 6:40:03 AM UTC, Brent wrote:



 On 12/23/2018 8:22 PM, agrays...@gmail.com wrote:



 On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote:
>
>
>
> On 12/23/2018 4:47 PM, agrays...@gmail.com wrote:
>
> *If by "flat", you mean mathematically flat, like a plane
> extending infinitely in all directions, as opposed to asymptotically 
> flat
> like a huge and expanding sphere,  you have to reconcile an 
> infinitesimally
> tiny universe at the time of the BB, and simultaneously an infinitely 
> large
> universe extending infinitely in all directions. AG*
>
>
> All that's "infinitesimally tiny" is the visible universe.  You
> must know that the Friedmann equation just defines the dynamics of a 
> scale
> factor, not a size.
>

 *Are you claiming the visible universe at the BB was
 infinitesimally tiny, but the non visible part was infinitely large
 (mathematically flat), or huge (asymptotically flat)? AG *


 Right.  Although we can't be sure whether it is actually flat or
 just very big.

 Brent

>>>
>>> *OK. Agreed. We seemed to disagree on this in the past, but maybe we
>>> miscommunicated. AG*
>>>
>>
>> Here's what Ned Wright wrote.
>>
>> Is the Universe really infinite or just really big?
>>
>> We have observations that say that the radius of curvature of the
>> Universe is bigger than 70 billion light years. But the observations 
>> allow
>> for either a positive or negative curvature, and this range includes the
>> flat Universe with infinite radius of curvature. The negatively curved
>> space is also infinite in volume even though it is curved. So we know
>> empirically that the volume of the Universe is more than 20 times bigger
>> than volume of the observable Universe. Since we can only look at small
>> piece of an object that has a large radius of curvature, it looks flat. 
>> The
>> simplest mathematical model for computing the observed properties of the
>> Universe is then flat Euclidean space. This model is infinite, but what 
>> we
>> know about the Universe is that it is really big
>> .
>>
>>
>> 
>>
>> *It is misleading. He's referring to the VISIBLE universe and
>> concludes it might be infinite in spatial extent. Impossible due to its
>> finite age. I wrote him about this, but never received a reply.  AG*
>>
>>
>>
> It's only impossible if you believe the believe the big bang occurred
> only at a point, rather than everywhere.
>
> Consider that every point in space sees everything else around it
> flying away from it, such that if you rewound time, everything would 
> return
> to a single point centered at that location. But this is true for every
> point in space, so the implication is that the BigBang didn't happen at 
> one
> particular location long in the past, but at every point, including the
> period at the end of this sentence.
>

 *You seem inclined to extreme hypotheses for which there is no data. AG
 *

>
>
>>> This is the default "standard" model used used by cosmologists, it's
>>> called the concordance model, or the Lambda-CDM model. There is significant
>>> data for it.
>>>
>>
>> *I don't believe it. AG *
>>
>
> *I mean I don't believe your interpretation of the Concordance model. AG *
>
>>
>>
http://www.universeadventure.org/big_bang/expand-balance.htm

Jason

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Re: CMBR and Horizon Problem

[agrayson2000]

On Tuesday, December 25, 2018 at 2:13:46 AM UTC, agrays...@gmail.com wrote:
>
>
>
> On Tuesday, December 25, 2018 at 12:35:24 AM UTC, Jason wrote:
>>
>>
>>
>> On Mon, Dec 24, 2018 at 6:28 PM  wrote:
>>
>>>
>>>
>>> On Monday, December 24, 2018 at 9:47:52 PM UTC, Jason wrote:



 On Mon, Dec 24, 2018 at 4:04 PM  wrote:

>
>
> On Monday, December 24, 2018 at 8:25:11 PM UTC, agrays...@gmail.com 
> wrote:
>>
>>
>>
>> On Monday, December 24, 2018 at 6:40:03 AM UTC, Brent wrote:
>>>
>>>
>>>
>>> On 12/23/2018 8:22 PM, agrays...@gmail.com wrote:
>>>
>>>
>>>
>>> On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote: 



 On 12/23/2018 4:47 PM, agrays...@gmail.com wrote:

 *If by "flat", you mean mathematically flat, like a plane extending 
 infinitely in all directions, as opposed to asymptotically flat like a 
 huge 
 and expanding sphere,  you have to reconcile an infinitesimally tiny 
 universe at the time of the BB, and simultaneously an infinitely large 
 universe extending infinitely in all directions. AG*


 All that's "infinitesimally tiny" is the visible universe.  You 
 must know that the Friedmann equation just defines the dynamics of a 
 scale 
 factor, not a size.

>>>
>>> *Are you claiming the visible universe at the BB was infinitesimally 
>>> tiny, but the non visible part was infinitely large (mathematically 
>>> flat), 
>>> or huge (asymptotically flat)? AG *
>>>
>>>
>>> Right.  Although we can't be sure whether it is actually flat or 
>>> just very big.
>>>
>>> Brent
>>>
>>
>> *OK. Agreed. We seemed to disagree on this in the past, but maybe we 
>> miscommunicated. AG*
>>
>
> Here's what Ned Wright wrote. 
>
> Is the Universe really infinite or just really big?
>
> We have observations that say that the radius of curvature of the 
> Universe is bigger than 70 billion light years. But the observations 
> allow 
> for either a positive or negative curvature, and this range includes the 
> flat Universe with infinite radius of curvature. The negatively curved 
> space is also infinite in volume even though it is curved. So we know 
> empirically that the volume of the Universe is more than 20 times bigger 
> than volume of the observable Universe. Since we can only look at small 
> piece of an object that has a large radius of curvature, it looks flat. 
> The 
> simplest mathematical model for computing the observed properties of the 
> Universe is then flat Euclidean space. This model is infinite, but what 
> we 
> know about the Universe is that it is really big 
> .
>
>
> 
>
> *It is misleading. He's referring to the VISIBLE universe and 
> concludes it might be infinite in spatial extent. Impossible due to its 
> finite age. I wrote him about this, but never received a reply.  AG*
>
>
>
 It's only impossible if you believe the believe the big bang occurred 
 only at a point, rather than everywhere.

 Consider that every point in space sees everything else around it 
 flying away from it, such that if you rewound time, everything would 
 return 
 to a single point centered at that location. But this is true for every 
 point in space, so the implication is that the BigBang didn't happen at 
 one 
 particular location long in the past, but at every point, including the 
 period at the end of this sentence.

>>>
>>> *You seem inclined to extreme hypotheses for which there is no data. AG *
>>>


>> This is the default "standard" model used used by cosmologists, it's 
>> called the concordance model, or the Lambda-CDM model. There is significant 
>> data for it.
>>
>
> *I don't believe it. AG *
>

*I mean I don't believe your interpretation of the Concordance model. AG *

>
>
>> Jason
>>
>

-- 
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Re: CMBR and Horizon Problem

[agrayson2000]

On Tuesday, December 25, 2018 at 12:35:24 AM UTC, Jason wrote:
>
>
>
> On Mon, Dec 24, 2018 at 6:28 PM > wrote:
>
>>
>>
>> On Monday, December 24, 2018 at 9:47:52 PM UTC, Jason wrote:
>>>
>>>
>>>
>>> On Mon, Dec 24, 2018 at 4:04 PM  wrote:
>>>


 On Monday, December 24, 2018 at 8:25:11 PM UTC, agrays...@gmail.com 
 wrote:
>
>
>
> On Monday, December 24, 2018 at 6:40:03 AM UTC, Brent wrote:
>>
>>
>>
>> On 12/23/2018 8:22 PM, agrays...@gmail.com wrote:
>>
>>
>>
>> On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote: 
>>>
>>>
>>>
>>> On 12/23/2018 4:47 PM, agrays...@gmail.com wrote:
>>>
>>> *If by "flat", you mean mathematically flat, like a plane extending 
>>> infinitely in all directions, as opposed to asymptotically flat like a 
>>> huge 
>>> and expanding sphere,  you have to reconcile an infinitesimally tiny 
>>> universe at the time of the BB, and simultaneously an infinitely large 
>>> universe extending infinitely in all directions. AG*
>>>
>>>
>>> All that's "infinitesimally tiny" is the visible universe.  You must 
>>> know that the Friedmann equation just defines the dynamics of a scale 
>>> factor, not a size.
>>>
>>
>> *Are you claiming the visible universe at the BB was infinitesimally 
>> tiny, but the non visible part was infinitely large (mathematically 
>> flat), 
>> or huge (asymptotically flat)? AG *
>>
>>
>> Right.  Although we can't be sure whether it is actually flat or just 
>> very big.
>>
>> Brent
>>
>
> *OK. Agreed. We seemed to disagree on this in the past, but maybe we 
> miscommunicated. AG*
>

 Here's what Ned Wright wrote. 

 Is the Universe really infinite or just really big?

 We have observations that say that the radius of curvature of the 
 Universe is bigger than 70 billion light years. But the observations allow 
 for either a positive or negative curvature, and this range includes the 
 flat Universe with infinite radius of curvature. The negatively curved 
 space is also infinite in volume even though it is curved. So we know 
 empirically that the volume of the Universe is more than 20 times bigger 
 than volume of the observable Universe. Since we can only look at small 
 piece of an object that has a large radius of curvature, it looks flat. 
 The 
 simplest mathematical model for computing the observed properties of the 
 Universe is then flat Euclidean space. This model is infinite, but what we 
 know about the Universe is that it is really big 
 .


 

 *It is misleading. He's referring to the VISIBLE universe and concludes 
 it might be infinite in spatial extent. Impossible due to its finite age. 
 I 
 wrote him about this, but never received a reply.  AG*



>>> It's only impossible if you believe the believe the big bang occurred 
>>> only at a point, rather than everywhere.
>>>
>>> Consider that every point in space sees everything else around it flying 
>>> away from it, such that if you rewound time, everything would return to a 
>>> single point centered at that location. But this is true for every point in 
>>> space, so the implication is that the BigBang didn't happen at one 
>>> particular location long in the past, but at every point, including the 
>>> period at the end of this sentence.
>>>
>>
>> *You seem inclined to extreme hypotheses for which there is no data. AG *
>>
>>>
>>>
> This is the default "standard" model used used by cosmologists, it's 
> called the concordance model, or the Lambda-CDM model. There is significant 
> data for it.
>

*I don't believe it. AG *

>
> Jason
>

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Re: CMBR and Horizon Problem

[Jason Resch]

On Mon, Dec 24, 2018 at 6:28 PM  wrote:

>
>
> On Monday, December 24, 2018 at 9:47:52 PM UTC, Jason wrote:
>>
>>
>>
>> On Mon, Dec 24, 2018 at 4:04 PM  wrote:
>>
>>>
>>>
>>> On Monday, December 24, 2018 at 8:25:11 PM UTC, agrays...@gmail.com
>>> wrote:



 On Monday, December 24, 2018 at 6:40:03 AM UTC, Brent wrote:
>
>
>
> On 12/23/2018 8:22 PM, agrays...@gmail.com wrote:
>
>
>
> On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote:
>>
>>
>>
>> On 12/23/2018 4:47 PM, agrays...@gmail.com wrote:
>>
>> *If by "flat", you mean mathematically flat, like a plane extending
>> infinitely in all directions, as opposed to asymptotically flat like a 
>> huge
>> and expanding sphere,  you have to reconcile an infinitesimally tiny
>> universe at the time of the BB, and simultaneously an infinitely large
>> universe extending infinitely in all directions. AG*
>>
>>
>> All that's "infinitesimally tiny" is the visible universe.  You must
>> know that the Friedmann equation just defines the dynamics of a scale
>> factor, not a size.
>>
>
> *Are you claiming the visible universe at the BB was infinitesimally
> tiny, but the non visible part was infinitely large (mathematically flat),
> or huge (asymptotically flat)? AG *
>
>
> Right.  Although we can't be sure whether it is actually flat or just
> very big.
>
> Brent
>

 *OK. Agreed. We seemed to disagree on this in the past, but maybe we
 miscommunicated. AG*

>>>
>>> Here's what Ned Wright wrote.
>>>
>>> Is the Universe really infinite or just really big?
>>>
>>> We have observations that say that the radius of curvature of the
>>> Universe is bigger than 70 billion light years. But the observations allow
>>> for either a positive or negative curvature, and this range includes the
>>> flat Universe with infinite radius of curvature. The negatively curved
>>> space is also infinite in volume even though it is curved. So we know
>>> empirically that the volume of the Universe is more than 20 times bigger
>>> than volume of the observable Universe. Since we can only look at small
>>> piece of an object that has a large radius of curvature, it looks flat. The
>>> simplest mathematical model for computing the observed properties of the
>>> Universe is then flat Euclidean space. This model is infinite, but what we
>>> know about the Universe is that it is really big
>>> .
>>>
>>>
>>> 
>>>
>>> *It is misleading. He's referring to the VISIBLE universe and concludes
>>> it might be infinite in spatial extent. Impossible due to its finite age. I
>>> wrote him about this, but never received a reply.  AG*
>>>
>>>
>>>
>> It's only impossible if you believe the believe the big bang occurred
>> only at a point, rather than everywhere.
>>
>> Consider that every point in space sees everything else around it flying
>> away from it, such that if you rewound time, everything would return to a
>> single point centered at that location. But this is true for every point in
>> space, so the implication is that the BigBang didn't happen at one
>> particular location long in the past, but at every point, including the
>> period at the end of this sentence.
>>
>
> *You seem inclined to extreme hypotheses for which there is no data. AG *
>
>>
>>
This is the default "standard" model used used by cosmologists, it's called
the concordance model, or the Lambda-CDM model. There is significant data
for it.

Jason

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Re: CMBR and Horizon Problem

[John Clark]

On Mon, Dec 24, 2018 at 4:35 PM Bruce Kellett  wrote:

> *You seem to be convinced by inflation theory. *
>

No I'm just playing devil's advocate. I'm not convinced it's right I'm just
not convinced it's dead wrong as you seem to be.

*> Why has the inflation not been seen at LHC?*
>

The LHC just went offline, when it comes back online after 2 years of
upgrades it should reach energies close to 15 TeV which corresponds to a
temperature of 10^17 Kelvin, and that is the temperature the entire
universe was in when it was about 10^-17 seconds old. But inflation was
over by the time the universe was 10^-35 seconds old. To inflation the
universe was already ancient when it was 10^-17 seconds old.

This may be related to the fact that no particle accelerator has found
anything surprising in 50 years; but telescopes have, they've revealed new
physics to us.


> *> At the end of the inflationary period, the temperature was absolute
> zero everywhere -- no fluctuations.*
>

If something was at absolute zero it would violate the third law of
thermodynamics. It would also violate quantum mechanics because you'd know
exactly what the velocity of a particle was (zero) and therefore its
position would not be meaningful because division by zero is not defined.

 John K Clark

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Re: CMBR and Horizon Problem

[agrayson2000]

On Monday, December 24, 2018 at 10:42:10 PM UTC, Brent wrote:
>
>
>
> On 12/24/2018 1:04 PM, agrays...@gmail.com  wrote:
>
>
>
> On Monday, December 24, 2018 at 8:25:11 PM UTC, agrays...@gmail.com 
> wrote: 
>>
>>
>>
>> On Monday, December 24, 2018 at 6:40:03 AM UTC, Brent wrote: 
>>>
>>>
>>>
>>> On 12/23/2018 8:22 PM, agrays...@gmail.com wrote:
>>>
>>>
>>>
>>> On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote: 



 On 12/23/2018 4:47 PM, agrays...@gmail.com wrote:

 *If by "flat", you mean mathematically flat, like a plane extending 
 infinitely in all directions, as opposed to asymptotically flat like a 
 huge 
 and expanding sphere,  you have to reconcile an infinitesimally tiny 
 universe at the time of the BB, and simultaneously an infinitely large 
 universe extending infinitely in all directions. AG*


 All that's "infinitesimally tiny" is the visible universe.  You must 
 know that the Friedmann equation just defines the dynamics of a scale 
 factor, not a size.

>>>
>>> *Are you claiming the visible universe at the BB was infinitesimally 
>>> tiny, but the non visible part was infinitely large (mathematically flat), 
>>> or huge (asymptotically flat)? AG *
>>>
>>>
>>> Right.  Although we can't be sure whether it is actually flat or just 
>>> very big.
>>>
>>> Brent
>>>
>>
>> *OK. Agreed. We seemed to disagree on this in the past, but maybe we 
>> miscommunicated. AG*
>>
>
> Here's what Ned Wright wrote. 
>
> Is the Universe really infinite or just really big? 
>
> We have observations that say that the radius of curvature of the Universe 
> is bigger than 70 billion light years. But the observations allow for 
> either a positive or negative curvature, and this range includes the flat 
> Universe with infinite radius of curvature. The negatively curved space is 
> also infinite in volume even though it is curved. So we know empirically 
> that the volume of the Universe is more than 20 times bigger than volume of 
> the observable Universe. Since we can only look at small piece of an object 
> that has a large radius of curvature, it looks flat. The simplest 
> mathematical model for computing the observed properties of the Universe is 
> then flat Euclidean space. This model is infinite, but what we know about 
> the Universe is that it is really big 
> .
>
>
> 
>
> *It is misleading. He's referring to the VISIBLE universe and concludes it 
> might be infinite in spatial extent. Impossible due to its finite age. I 
> wrote him about this, but never received a reply.  AG*
>
>
> Why don't you look at his web tutorial.  He does not conclude the 
> *visible* universe might be infinite.
>

*From the statement above, due to poor use of language, it seems he 
concludes the visible universe might be infinite.  I didn't see that 
corrected anywhere in his tutorial, but I didn't read it in its entirety. 
AG*

>
> Brent
>

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Re: CMBR and Horizon Problem

[agrayson2000]

On Monday, December 24, 2018 at 9:47:52 PM UTC, Jason wrote:
>
>
>
> On Mon, Dec 24, 2018 at 4:04 PM > wrote:
>
>>
>>
>> On Monday, December 24, 2018 at 8:25:11 PM UTC, agrays...@gmail.com 
>> wrote:
>>>
>>>
>>>
>>> On Monday, December 24, 2018 at 6:40:03 AM UTC, Brent wrote:



 On 12/23/2018 8:22 PM, agrays...@gmail.com wrote:



 On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote: 
>
>
>
> On 12/23/2018 4:47 PM, agrays...@gmail.com wrote:
>
> *If by "flat", you mean mathematically flat, like a plane extending 
> infinitely in all directions, as opposed to asymptotically flat like a 
> huge 
> and expanding sphere,  you have to reconcile an infinitesimally tiny 
> universe at the time of the BB, and simultaneously an infinitely large 
> universe extending infinitely in all directions. AG*
>
>
> All that's "infinitesimally tiny" is the visible universe.  You must 
> know that the Friedmann equation just defines the dynamics of a scale 
> factor, not a size.
>

 *Are you claiming the visible universe at the BB was infinitesimally 
 tiny, but the non visible part was infinitely large (mathematically flat), 
 or huge (asymptotically flat)? AG *


 Right.  Although we can't be sure whether it is actually flat or just 
 very big.

 Brent

>>>
>>> *OK. Agreed. We seemed to disagree on this in the past, but maybe we 
>>> miscommunicated. AG*
>>>
>>
>> Here's what Ned Wright wrote. 
>>
>> Is the Universe really infinite or just really big?
>>
>> We have observations that say that the radius of curvature of the 
>> Universe is bigger than 70 billion light years. But the observations allow 
>> for either a positive or negative curvature, and this range includes the 
>> flat Universe with infinite radius of curvature. The negatively curved 
>> space is also infinite in volume even though it is curved. So we know 
>> empirically that the volume of the Universe is more than 20 times bigger 
>> than volume of the observable Universe. Since we can only look at small 
>> piece of an object that has a large radius of curvature, it looks flat. The 
>> simplest mathematical model for computing the observed properties of the 
>> Universe is then flat Euclidean space. This model is infinite, but what we 
>> know about the Universe is that it is really big 
>> .
>>
>>
>> 
>>
>> *It is misleading. He's referring to the VISIBLE universe and concludes 
>> it might be infinite in spatial extent. Impossible due to its finite age. I 
>> wrote him about this, but never received a reply.  AG*
>>
>>
>>
> It's only impossible if you believe the believe the big bang occurred only 
> at a point, rather than everywhere.
>
> Consider that every point in space sees everything else around it flying 
> away from it, such that if you rewound time, everything would return to a 
> single point centered at that location. But this is true for every point in 
> space, so the implication is that the BigBang didn't happen at one 
> particular location long in the past, but at every point, including the 
> period at the end of this sentence.
>

*You seem inclined to extreme hypotheses for which there is no data. AG *

>
> Jason
>

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Re: CMBR and Horizon Problem

[Brent Meeker]

On 12/24/2018 1:04 PM, agrayson2...@gmail.com wrote:



On Monday, December 24, 2018 at 8:25:11 PM UTC, agrays...@gmail.com 
wrote:




On Monday, December 24, 2018 at 6:40:03 AM UTC, Brent wrote:



On 12/23/2018 8:22 PM, agrays...@gmail.com wrote:



On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote:



On 12/23/2018 4:47 PM, agrays...@gmail.com wrote:

*If by "flat", you mean mathematically flat, like a
plane extending infinitely in all directions, as opposed
to asymptotically flat like a huge and expanding
sphere,  you have to reconcile an infinitesimally tiny
universe at the time of the BB, and simultaneously an
infinitely large universe extending infinitely in all
directions. AG*


All that's "infinitesimally tiny" is the visible
universe.  You must know that the Friedmann equation just
defines the dynamics of a scale factor, not a size.


*Are you claiming the visible universe at the BB was
infinitesimally tiny, but the non visible part was infinitely
large (mathematically flat), or huge (asymptotically flat)? AG *


Right.  Although we can't be sure whether it is actually flat
or just very big.

Brent


*OK. Agreed. We seemed to disagree on this in the past, but maybe
we miscommunicated. AG*


Here's what Ned Wright wrote.


Is the Universe really infinite or just really big?

We have observations that say that the radius of curvature of the 
Universe is bigger than 70 billion light years. But the observations 
allow for either a positive or negative curvature, and this range 
includes the flat Universe with infinite radius of curvature. The 
negatively curved space is also infinite in volume even though it is 
curved. So we know empirically that the volume of the Universe is more 
than 20 times bigger than volume of the observable Universe. Since we 
can only look at small piece of an object that has a large radius of 
curvature, it looks flat. The simplest mathematical model for 
computing the observed properties of the Universe is then flat 
Euclidean space. This model is infinite, but what we know about the 
Universe is that it isreally big 
.





*
*
*It is misleading. He's referring to the VISIBLE universe and 
concludes it might be infinite in spatial extent. Impossible due to 
its finite age. I wrote him about this, but never received a reply.  AG*


Why don't you look at his web tutorial.  He does not conclude the 
/*visible*/ universe might be infinite.


Brent

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Re: CMBR and Horizon Problem

[Bruce Kellett]

On Tue, Dec 25, 2018 at 8:44 AM  wrote:

> On Monday, December 24, 2018 at 9:35:05 PM UTC, Bruce wrote:
>>
>> On Tue, Dec 25, 2018 at 4:43 AM John Clark  wrote:
>>
>>> On Sun, Dec 23, 2018 at 5:38 PM Bruce Kellett 
>>> wrote:
>>>
>>> *> 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.*
>>>>
>>>
>>> There are an infinite number of ways space could have been curved but
>>> you picked one particular way (no curvature at all) for your initial
>>> conditions and did so for no particular reason other than to make the
>>> theory fit the facts that you already knew. Inflation explains why
>>> spacetime curvature could have any finite value whatsoever when the
>>> universe first came into existence and it would still look flat today even
>>> with our most sensitive instruments. It didn't have to start out with
>>> spacetime being zero or anything close to it, and that doesn't sound
>>> fined-tuned to me.
>>>
>>> And the same thing is true of temperature, why are things at the same
>>> temperature when there was no time for them to come into thermal
>>> equilibrium? Inflation explains why, your explanation is they just did.
>>> Inflation says that  10^-35 seconds after the start of the universe and it
>>> had doubled in size about a hundred times  (and 10^35 seconds is a long
>>> long time compared to the Planck Time of 10^-43 seconds) the difference in
>>> temperature in our part of the universe would be almost zero but not
>>> precisely zero due to random quantum variations, and quantum theory allows
>>> you to calculate the intensity and size of what those temperature
>>> variations should have been. And you can also calculate what those
>>> temperature variations would evolve into after the universe has been
>>> expanding for 380,000 years, and what we calculate and what we see are the
>>> same.
>>>
>>> That's also how we know that at the very largest scale the universe is
>>> in general flat. They did this by looking at the oldest thing we can
>>> see, the Cosmic Microwave Background Radiation (CMBR) formed just 380,000
>>> years after the Big Bang. So if we look at a map of that background
>>> radiation the largest structure we could see on it would be 380,000 light
>>> years across, spots larger than that wouldn't have had enough time to form
>>> because nothing, not even gravity can move faster than light, a larger lump
>>> wouldn't even have enough time to know it was a lump.
>>>
>>> So how large would an object 13.8 billion light years away appear to us
>>> if it's size was 380,000 light years across? The answer is one degree of
>>> arc, but ONLY if the universe is flat. If it's not flat and parallel lines
>>> converge or diverge then the image of the largest structures we can see in
>>> the CMBR could appear to be larger or smaller than one degree depending on
>>> how the image was distorted, and that would depend on if the universe is
>>> positively or negatively curved.  But we see no distortion at all, in this
>>> way the WMAP and Planck satellite proved that the universe is in general
>>> flat, or at least isn't curved much, over a distance of 13.8 billion light
>>> years if the universe curves at all it is less than one part in 100,000.
>>>
>>>
>>>> >> 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?*
>>>>
>>>
>>> From the same place gravitational potential does I suppose, but
>>> inflation would be simpler, in General Relativity gravity needs a tensor
>>> field but inflation only needs a scalar field.
>>>
>>>
>>>>  > *Why don't we see the inflaton?*
>>>>
>>>
>>> Maybe we do see it, maybe the acceleration of the universe we see today
>>> is the inflation field at work having undergone a  phase change when the
>>> universe was 10^-35 sec old and switched into a much lower gear. Or maybe
>>> not. Andrei Linde thinks the inflation field decayes away like radioactive
>>> half life, and after th

Re: CMBR and Horizon Problem

[Jason Resch]

On Mon, Dec 24, 2018 at 4:04 PM  wrote:

>
>
> On Monday, December 24, 2018 at 8:25:11 PM UTC, agrays...@gmail.com wrote:
>>
>>
>>
>> On Monday, December 24, 2018 at 6:40:03 AM UTC, Brent wrote:
>>>
>>>
>>>
>>> On 12/23/2018 8:22 PM, agrays...@gmail.com wrote:
>>>
>>>
>>>
>>> On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote:



 On 12/23/2018 4:47 PM, agrays...@gmail.com wrote:

 *If by "flat", you mean mathematically flat, like a plane extending
 infinitely in all directions, as opposed to asymptotically flat like a huge
 and expanding sphere,  you have to reconcile an infinitesimally tiny
 universe at the time of the BB, and simultaneously an infinitely large
 universe extending infinitely in all directions. AG*


 All that's "infinitesimally tiny" is the visible universe.  You must
 know that the Friedmann equation just defines the dynamics of a scale
 factor, not a size.

>>>
>>> *Are you claiming the visible universe at the BB was infinitesimally
>>> tiny, but the non visible part was infinitely large (mathematically flat),
>>> or huge (asymptotically flat)? AG *
>>>
>>>
>>> Right.  Although we can't be sure whether it is actually flat or just
>>> very big.
>>>
>>> Brent
>>>
>>
>> *OK. Agreed. We seemed to disagree on this in the past, but maybe we
>> miscommunicated. AG*
>>
>
> Here's what Ned Wright wrote.
>
> Is the Universe really infinite or just really big?
>
> We have observations that say that the radius of curvature of the Universe
> is bigger than 70 billion light years. But the observations allow for
> either a positive or negative curvature, and this range includes the flat
> Universe with infinite radius of curvature. The negatively curved space is
> also infinite in volume even though it is curved. So we know empirically
> that the volume of the Universe is more than 20 times bigger than volume of
> the observable Universe. Since we can only look at small piece of an object
> that has a large radius of curvature, it looks flat. The simplest
> mathematical model for computing the observed properties of the Universe is
> then flat Euclidean space. This model is infinite, but what we know about
> the Universe is that it is really big
> .
>
>
> 
>
> *It is misleading. He's referring to the VISIBLE universe and concludes it
> might be infinite in spatial extent. Impossible due to its finite age. I
> wrote him about this, but never received a reply.  AG*
>
>
>
It's only impossible if you believe the believe the big bang occurred only
at a point, rather than everywhere.

Consider that every point in space sees everything else around it flying
away from it, such that if you rewound time, everything would return to a
single point centered at that location. But this is true for every point in
space, so the implication is that the BigBang didn't happen at one
particular location long in the past, but at every point, including the
period at the end of this sentence.

Jason

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Re: CMBR and Horizon Problem

[agrayson2000]

On Monday, December 24, 2018 at 9:35:05 PM UTC, Bruce wrote:
>
> On Tue, Dec 25, 2018 at 4:43 AM John Clark  > wrote:
>
>> On Sun, Dec 23, 2018 at 5:38 PM Bruce Kellett > > wrote:
>>
>> *> 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.*
>>>
>>
>> There are an infinite number of ways space could have been curved but you 
>> picked one particular way (no curvature at all) for your initial conditions 
>> and did so for no particular reason other than to make the theory fit the 
>> facts that you already knew. Inflation explains why spacetime curvature 
>> could have any finite value whatsoever when the universe first came into 
>> existence and it would still look flat today even with our most sensitive 
>> instruments. It didn't have to start out with spacetime being zero or 
>> anything close to it, and that doesn't sound  fined-tuned to me.
>>
>> And the same thing is true of temperature, why are things at the same 
>> temperature when there was no time for them to come into thermal 
>> equilibrium? Inflation explains why, your explanation is they just did.  
>> Inflation says that  10^-35 seconds after the start of the universe and it 
>> had doubled in size about a hundred times  (and 10^35 seconds is a long 
>> long time compared to the Planck Time of 10^-43 seconds) the difference in 
>> temperature in our part of the universe would be almost zero but not 
>> precisely zero due to random quantum variations, and quantum theory allows 
>> you to calculate the intensity and size of what those temperature 
>> variations should have been. And you can also calculate what those 
>> temperature variations would evolve into after the universe has been 
>> expanding for 380,000 years, and what we calculate and what we see are the 
>> same.
>>
>> That's also how we know that at the very largest scale the universe is 
>> in general flat. They did this by looking at the oldest thing we can 
>> see, the Cosmic Microwave Background Radiation (CMBR) formed just 380,000 
>> years after the Big Bang. So if we look at a map of that background 
>> radiation the largest structure we could see on it would be 380,000 light 
>> years across, spots larger than that wouldn't have had enough time to form 
>> because nothing, not even gravity can move faster than light, a larger lump 
>> wouldn't even have enough time to know it was a lump. 
>>
>> So how large would an object 13.8 billion light years away appear to us 
>> if it's size was 380,000 light years across? The answer is one degree of 
>> arc, but ONLY if the universe is flat. If it's not flat and parallel lines 
>> converge or diverge then the image of the largest structures we can see in 
>> the CMBR could appear to be larger or smaller than one degree depending on 
>> how the image was distorted, and that would depend on if the universe is 
>> positively or negatively curved.  But we see no distortion at all, in this 
>> way the WMAP and Planck satellite proved that the universe is in general 
>> flat, or at least isn't curved much, over a distance of 13.8 billion light 
>> years if the universe curves at all it is less than one part in 100,000.
>>  
>>
>>> >> 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?*
>>>
>>
>> From the same place gravitational potential does I suppose, but inflation 
>> would be simpler, in General Relativity gravity needs a tensor field but 
>> inflation only needs a scalar field.
>>  
>>
>>>  > *Why don't we see the inflaton?*
>>>
>>
>> Maybe we do see it, maybe the acceleration of the universe we see today 
>> is the inflation field at work having undergone a  phase change when the 
>> universe was 10^-35 sec old and switched into a much lower gear. Or maybe 
>> not. Andrei Linde thinks the inflation field decayes away like radioactive 
>> half life, and after the decay the universe expanded at a much much more 
>> leisurely pace. But for that idea to work Guth's the inflation field had to 
>> expand faster than it decayed, Linde called it "Eternal Inflation". Linde 
>> showed that for every volume in which the inflation field decays away 2

Re: CMBR and Horizon Problem

[Bruce Kellett]

On Tue, Dec 25, 2018 at 4:43 AM John Clark  wrote:

> On Sun, Dec 23, 2018 at 5:38 PM Bruce Kellett 
> wrote:
>
> *> 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.*
>>
>
> There are an infinite number of ways space could have been curved but you
> picked one particular way (no curvature at all) for your initial conditions
> and did so for no particular reason other than to make the theory fit the
> facts that you already knew. Inflation explains why spacetime curvature
> could have any finite value whatsoever when the universe first came into
> existence and it would still look flat today even with our most sensitive
> instruments. It didn't have to start out with spacetime being zero or
> anything close to it, and that doesn't sound  fined-tuned to me.
>
> And the same thing is true of temperature, why are things at the same
> temperature when there was no time for them to come into thermal
> equilibrium? Inflation explains why, your explanation is they just did.
> Inflation says that  10^-35 seconds after the start of the universe and it
> had doubled in size about a hundred times  (and 10^35 seconds is a long
> long time compared to the Planck Time of 10^-43 seconds) the difference in
> temperature in our part of the universe would be almost zero but not
> precisely zero due to random quantum variations, and quantum theory allows
> you to calculate the intensity and size of what those temperature
> variations should have been. And you can also calculate what those
> temperature variations would evolve into after the universe has been
> expanding for 380,000 years, and what we calculate and what we see are the
> same.
>
> That's also how we know that at the very largest scale the universe is in
> general flat. They did this by looking at the oldest thing we can see,
> the Cosmic Microwave Background Radiation (CMBR) formed just 380,000 years
> after the Big Bang. So if we look at a map of that background radiation the
> largest structure we could see on it would be 380,000 light years across,
> spots larger than that wouldn't have had enough time to form because
> nothing, not even gravity can move faster than light, a larger lump
> wouldn't even have enough time to know it was a lump.
>
> So how large would an object 13.8 billion light years away appear to us if
> it's size was 380,000 light years across? The answer is one degree of arc,
> but ONLY if the universe is flat. If it's not flat and parallel lines
> converge or diverge then the image of the largest structures we can see in
> the CMBR could appear to be larger or smaller than one degree depending on
> how the image was distorted, and that would depend on if the universe is
> positively or negatively curved.  But we see no distortion at all, in this
> way the WMAP and Planck satellite proved that the universe is in general
> flat, or at least isn't curved much, over a distance of 13.8 billion light
> years if the universe curves at all it is less than one part in 100,000.
>
>
>> >> 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?*
>>
>
> From the same place gravitational potential does I suppose, but inflation
> would be simpler, in General Relativity gravity needs a tensor field but
> inflation only needs a scalar field.
>
>
>>  > *Why don't we see the inflaton?*
>>
>
> Maybe we do see it, maybe the acceleration of the universe we see today is
> the inflation field at work having undergone a  phase change when the
> universe was 10^-35 sec old and switched into a much lower gear. Or maybe
> not. Andrei Linde thinks the inflation field decayes away like radioactive
> half life, and after the decay the universe expanded at a much much more
> leisurely pace. But for that idea to work Guth's the inflation field had to
> expand faster than it decayed, Linde called it "Eternal Inflation". Linde
> showed that for every volume in which the inflation field decays away 2
> other volumes don't decay. So one universe becomes 3, the field decays in
> one universe but not in the other 2, then both of those two universes
> splits in 3 again and the inflation field decays away in two of them but
> doesn't decay in the other 4.  And it goes on like this forever creating a
> multiverse.
>
> If any of this is true we may be able to prove it because Eternal
> Inflation would create gra

Re: CMBR and Horizon Problem

[agrayson2000]

On Monday, December 24, 2018 at 8:25:11 PM UTC, agrays...@gmail.com wrote:
>
>
>
> On Monday, December 24, 2018 at 6:40:03 AM UTC, Brent wrote:
>>
>>
>>
>> On 12/23/2018 8:22 PM, agrays...@gmail.com wrote:
>>
>>
>>
>> On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote: 
>>>
>>>
>>>
>>> On 12/23/2018 4:47 PM, agrays...@gmail.com wrote:
>>>
>>> *If by "flat", you mean mathematically flat, like a plane extending 
>>> infinitely in all directions, as opposed to asymptotically flat like a huge 
>>> and expanding sphere,  you have to reconcile an infinitesimally tiny 
>>> universe at the time of the BB, and simultaneously an infinitely large 
>>> universe extending infinitely in all directions. AG*
>>>
>>>
>>> All that's "infinitesimally tiny" is the visible universe.  You must 
>>> know that the Friedmann equation just defines the dynamics of a scale 
>>> factor, not a size.
>>>
>>
>> *Are you claiming the visible universe at the BB was infinitesimally 
>> tiny, but the non visible part was infinitely large (mathematically flat), 
>> or huge (asymptotically flat)? AG *
>>
>>
>> Right.  Although we can't be sure whether it is actually flat or just 
>> very big.
>>
>> Brent
>>
>
> *OK. Agreed. We seemed to disagree on this in the past, but maybe we 
> miscommunicated. AG*
>

Here's what Ned Wright wrote. 

Is the Universe really infinite or just really big?

We have observations that say that the radius of curvature of the Universe 
is bigger than 70 billion light years. But the observations allow for 
either a positive or negative curvature, and this range includes the flat 
Universe with infinite radius of curvature. The negatively curved space is 
also infinite in volume even though it is curved. So we know empirically 
that the volume of the Universe is more than 20 times bigger than volume of 
the observable Universe. Since we can only look at small piece of an object 
that has a large radius of curvature, it looks flat. The simplest 
mathematical model for computing the observed properties of the Universe is 
then flat Euclidean space. This model is infinite, but what we know about 
the Universe is that it is really big 
.




*It is misleading. He's referring to the VISIBLE universe and concludes it 
might be infinite in spatial extent. Impossible due to its finite age. I 
wrote him about this, but never received a reply.  AG*

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Re: CMBR and Horizon Problem

[agrayson2000]

On Monday, December 24, 2018 at 5:52:21 PM UTC, John Clark wrote:
>
> On Sun, Dec 23, 2018 at 7:47 PM > wrote:
>
> *> **If by "flat", you mean mathematically flat, like a plane extending 
>> infinitely in all directions, as opposed to asymptotically flat like a huge 
>> and expanding sphere,  you have to reconcile an infinitesimally tiny 
>> universe at the time of the BB, and simultaneously an infinitely large 
>> universe extending infinitely in all directions. AG*
>>
>
> You can never prove that any physical quantity is exactly zero, but we do 
> know from observations of the cosmic microwave background radiation that if 
> the universe is curved at all it is by less than one part in 100,000.
>
>  John K Clark
>

*Agreed. However, IMO the observed universe cannot be flat with exactly 
zero curvature, since that would imply infinite volume which contradicts 
its finite age. That is, if the observable universe started as 
infinitesimally small, and evolves for a finite time until the present, it 
cannot be mathematically flat. I believe it is shaped like a huge 
hyper-dimensional sphere, close to, but not "flat. The unobserved part 
could possibly be mathematically flat and therefore infinite in extent. I 
have discussed this with Brent in the past and he seems to disagree with my 
conclusion. But maybe we mis-communicated. AG*

>

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Re: CMBR and Horizon Problem

[agrayson2000]

On Monday, December 24, 2018 at 6:40:03 AM UTC, Brent wrote:
>
>
>
> On 12/23/2018 8:22 PM, agrays...@gmail.com  wrote:
>
>
>
> On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote: 
>>
>>
>>
>> On 12/23/2018 4:47 PM, agrays...@gmail.com wrote:
>>
>> *If by "flat", you mean mathematically flat, like a plane extending 
>> infinitely in all directions, as opposed to asymptotically flat like a huge 
>> and expanding sphere,  you have to reconcile an infinitesimally tiny 
>> universe at the time of the BB, and simultaneously an infinitely large 
>> universe extending infinitely in all directions. AG*
>>
>>
>> All that's "infinitesimally tiny" is the visible universe.  You must know 
>> that the Friedmann equation just defines the dynamics of a scale factor, 
>> not a size.
>>
>
> *Are you claiming the visible universe at the BB was infinitesimally tiny, 
> but the non visible part was infinitely large (mathematically flat), or 
> huge (asymptotically flat)? AG *
>
>
> Right.  Although we can't be sure whether it is actually flat or just very 
> big.
>
> Brent
>

*OK. Agreed. We seemed to disagree on this in the past, but maybe we 
miscommunicated. AG*

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Re: CMBR and Horizon Problem

[agrayson2000]

On Monday, December 24, 2018 at 5:52:21 PM UTC, John Clark wrote:
>
> On Sun, Dec 23, 2018 at 7:47 PM > wrote:
>
> *> **If by "flat", you mean mathematically flat, like a plane extending 
>> infinitely in all directions, as opposed to asymptotically flat like a huge 
>> and expanding sphere,  you have to reconcile an infinitesimally tiny 
>> universe at the time of the BB, and simultaneously an infinitely large 
>> universe extending infinitely in all directions. AG*
>>
>
> You can never prove that any physical quantity is exactly zero, but we do 
> know from observations of the cosmic microwave background radiation that if 
> the universe is curved at all it is by less than one part in 100,000.
>
>  John K Clark
>

*Agreed. However, IMO the observed universe cannot be flat with exactly 
zero curvature (which I refer to as "mathematically flat) since that would 
imply infinite volume which contradicts its finite age. That is, if the 
observable universe started as infinitesimally small, and evolves for a 
finite time until the present, it cannot be mathematically flat. I believe 
it is shaped like a huge hyper-dimensional sphere, close to, but not 
exactly "flat. The unobserved part could possibly be mathematically flat 
and therefore infinite in extent. I have discussed this with Brent in the 
past and he seems to disagree with my conclusion. But maybe we 
mis-communicated. AG*

>

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Re: CMBR and Horizon Problem

[John Clark]

On Sun, Dec 23, 2018 at 7:47 PM  wrote:

*> **If by "flat", you mean mathematically flat, like a plane extending
> infinitely in all directions, as opposed to asymptotically flat like a huge
> and expanding sphere,  you have to reconcile an infinitesimally tiny
> universe at the time of the BB, and simultaneously an infinitely large
> universe extending infinitely in all directions. AG*
>

You can never prove that any physical quantity is exactly zero, but we do
know from observations of the cosmic microwave background radiation that if
the universe is curved at all it is by less than one part in 100,000.

 John K Clark

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Re: CMBR and Horizon Problem

[John Clark]

On Sun, Dec 23, 2018 at 5:38 PM Bruce Kellett  wrote:

*> 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.*
>

There are an infinite number of ways space could have been curved but you
picked one particular way (no curvature at all) for your initial conditions
and did so for no particular reason other than to make the theory fit the
facts that you already knew. Inflation explains why spacetime curvature
could have any finite value whatsoever when the universe first came into
existence and it would still look flat today even with our most sensitive
instruments. It didn't have to start out with spacetime being zero or
anything close to it, and that doesn't sound  fined-tuned to me.

And the same thing is true of temperature, why are things at the same
temperature when there was no time for them to come into thermal
equilibrium? Inflation explains why, your explanation is they just did.
Inflation says that  10^-35 seconds after the start of the universe and it
had doubled in size about a hundred times  (and 10^35 seconds is a long
long time compared to the Planck Time of 10^-43 seconds) the difference in
temperature in our part of the universe would be almost zero but not
precisely zero due to random quantum variations, and quantum theory allows
you to calculate the intensity and size of what those temperature
variations should have been. And you can also calculate what those
temperature variations would evolve into after the universe has been
expanding for 380,000 years, and what we calculate and what we see are the
same.

That's also how we know that at the very largest scale the universe is in
general flat. They did this by looking at the oldest thing we can see, the
Cosmic Microwave Background Radiation (CMBR) formed just 380,000 years
after the Big Bang. So if we look at a map of that background radiation the
largest structure we could see on it would be 380,000 light years across,
spots larger than that wouldn't have had enough time to form because
nothing, not even gravity can move faster than light, a larger lump
wouldn't even have enough time to know it was a lump.

So how large would an object 13.8 billion light years away appear to us if
it's size was 380,000 light years across? The answer is one degree of arc,
but ONLY if the universe is flat. If it's not flat and parallel lines
converge or diverge then the image of the largest structures we can see in
the CMBR could appear to be larger or smaller than one degree depending on
how the image was distorted, and that would depend on if the universe is
positively or negatively curved.  But we see no distortion at all, in this
way the WMAP and Planck satellite proved that the universe is in general
flat, or at least isn't curved much, over a distance of 13.8 billion light
years if the universe curves at all it is less than one part in 100,000.


> >> 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?*
>

>From the same place gravitational potential does I suppose, but inflation
would be simpler, in General Relativity gravity needs a tensor field but
inflation only needs a scalar field.


>  > *Why don't we see the inflaton?*
>

Maybe we do see it, maybe the acceleration of the universe we see today is
the inflation field at work having undergone a  phase change when the
universe was 10^-35 sec old and switched into a much lower gear. Or maybe
not. Andrei Linde thinks the inflation field decayes away like radioactive
half life, and after the decay the universe expanded at a much much more
leisurely pace. But for that idea to work Guth's the inflation field had to
expand faster than it decayed, Linde called it "Eternal Inflation". Linde
showed that for every volume in which the inflation field decays away 2
other volumes don't decay. So one universe becomes 3, the field decays in
one universe but not in the other 2, then both of those two universes
splits in 3 again and the inflation field decays away in two of them but
doesn't decay in the other 4.  And it goes on like this forever creating a
multiverse.

If any of this is true we may be able to prove it because Eternal Inflation
would create gravitational waves with super long wavelengths that would
produce very slight changes in the polarization of the cosmic microwave
background radiation that we should be able to detect before long, assuming
they exist.

 John K Clark

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Re: CMBR and Horizon Problem

[agrayson2000]

On Monday, December 24, 2018 at 5:22:34 AM UTC, Bruce wrote:
>
> On Mon, Dec 24, 2018 at 4:02 PM > wrote:
>
>> On Monday, December 24, 2018 at 4:47:02 AM UTC, Bruce wrote:
>>>
>>> On Mon, Dec 24, 2018 at 3:33 PM  wrote:
>>>
 On Monday, December 24, 2018 at 4:22:24 AM UTC, agrays...@gmail.com 
 wrote:
>
> On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote:
>>
>> On 12/23/2018 4:47 PM, agrays...@gmail.com wrote:
>>
>> *If by "flat", you mean mathematically flat, like a plane extending 
>> infinitely in all directions, as opposed to asymptotically flat like a 
>> huge 
>> and expanding sphere,  you have to reconcile an infinitesimally tiny 
>> universe at the time of the BB, and simultaneously an infinitely large 
>> universe extending infinitely in all directions. AG*
>>
>>
>> All that's "infinitesimally tiny" is the visible universe.  You must 
>> know that the Friedmann equation just defines the dynamics of a scale 
>> factor, not a size.
>>
>
> *Are you claiming the visible universe at the BB was infinitesimally 
> tiny, but the non visible part was infinitely large (mathematically 
> flat), 
> or huge (asymptotically flat)? AG *
>

 *Bruce says the universe is always flat if k=1. How can it be 
 everywhere flat if there's a region which is infinitely tiny; hence not 
 flat in the visible region? How are we to imagine this? TIA, AG *

>>>
>>> That's a bit confused. k=0 corresponds to a universe that is everywhere 
>>> flat (in space, but not necessarily in the time dimension - i.e., it might 
>>> be expanding. Our current visible universe originated in a small (tiny) 
>>> region of the total structure, which might be infinite in extent, but flat 
>>> everywhere, even in our tiny region.
>>>
>>
>> *Not to split hairs, but how can the tiny visible region also be flat and 
>> infinite in extent, if its age is finite? I can imagine the visible region 
>> to be asymptotically (but not mathematically) flat, and therefore finite in 
>> extent. AG *
>>
>
> I said that the total structure might be infinite in extent, not the 
> region that became our visible universe. Flatness is a mathematical 
> property -- imagination readily fails to visualise these things.
>

*I can visualize it. The total structure might be infinite in extent (flat, 
possibly like a mathematical plane) or just very large, but the visible 
universe, being of finite age, can be no larger than asymptotically flat 
(like the surface of a huge expanding sphere) and thus finite in spatial 
extent. I've noticed that some cosmologists are sloppy in claiming the 
visible part is "flat" and infinite, which is impossible, failing to 
qualify "flat" to mean "asymptotically flat", finite in spatial extent 
because it has finite age. I think this answers Brent's issue with my 
comments as well. AG*



> Bruce
>

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Re: CMBR and Horizon Problem

[Brent Meeker]

On 12/23/2018 8:33 PM, agrayson2...@gmail.com wrote:



On Monday, December 24, 2018 at 4:22:24 AM UTC, agrays...@gmail.com 
wrote:




On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote:



On 12/23/2018 4:47 PM, agrays...@gmail.com wrote:

*If by "flat", you mean mathematically flat, like a plane
extending infinitely in all directions, as opposed to
asymptotically flat like a huge and expanding sphere,  you
have to reconcile an infinitesimally tiny universe at the
time of the BB, and simultaneously an infinitely large
universe extending infinitely in all directions. AG*


All that's "infinitesimally tiny" is the visible universe. 
You must know that the Friedmann equation just defines the
dynamics of a scale factor, not a size.


*Are you claiming the visible universe at the BB was
infinitesimally tiny, but the non visible part was infinitely
large (mathematically flat), or huge (asymptotically flat)? AG *


*Bruce says the universe is always flat if k=1. *


k=0

*How can it be everywhere flat if there's a region which is infinitely 
tiny; hence not flat in the visible region? *


?? How does a region being tiny keep it from being a tiny region of 
something flat?


Brent


*How are we to imagine this? TIA, AG *



Brent

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Re: CMBR and Horizon Problem

[Brent Meeker]

On 12/23/2018 8:22 PM, agrayson2...@gmail.com wrote:



On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote:



On 12/23/2018 4:47 PM, agrays...@gmail.com  wrote:

*If by "flat", you mean mathematically flat, like a plane
extending infinitely in all directions, as opposed to
asymptotically flat like a huge and expanding sphere,  you have
to reconcile an infinitesimally tiny universe at the time of the
BB, and simultaneously an infinitely large universe extending
infinitely in all directions. AG*


All that's "infinitesimally tiny" is the visible universe. You
must know that the Friedmann equation just defines the dynamics of
a scale factor, not a size.


*Are you claiming the visible universe at the BB was infinitesimally 
tiny, but the non visible part was infinitely large (mathematically 
flat), or huge (asymptotically flat)? AG *


Right.  Although we can't be sure whether it is actually flat or just 
very big.


Brent

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Re: CMBR and Horizon Problem

[Bruce Kellett]

On Mon, Dec 24, 2018 at 4:02 PM  wrote:

> On Monday, December 24, 2018 at 4:47:02 AM UTC, Bruce wrote:
>>
>> On Mon, Dec 24, 2018 at 3:33 PM  wrote:
>>
>>> On Monday, December 24, 2018 at 4:22:24 AM UTC, agrays...@gmail.com
>>> wrote:

 On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote:
>
> On 12/23/2018 4:47 PM, agrays...@gmail.com wrote:
>
> *If by "flat", you mean mathematically flat, like a plane extending
> infinitely in all directions, as opposed to asymptotically flat like a 
> huge
> and expanding sphere,  you have to reconcile an infinitesimally tiny
> universe at the time of the BB, and simultaneously an infinitely large
> universe extending infinitely in all directions. AG*
>
>
> All that's "infinitesimally tiny" is the visible universe.  You must
> know that the Friedmann equation just defines the dynamics of a scale
> factor, not a size.
>

 *Are you claiming the visible universe at the BB was infinitesimally
 tiny, but the non visible part was infinitely large (mathematically flat),
 or huge (asymptotically flat)? AG *

>>>
>>> *Bruce says the universe is always flat if k=1. How can it be everywhere
>>> flat if there's a region which is infinitely tiny; hence not flat in the
>>> visible region? How are we to imagine this? TIA, AG *
>>>
>>
>> That's a bit confused. k=0 corresponds to a universe that is everywhere
>> flat (in space, but not necessarily in the time dimension - i.e., it might
>> be expanding. Our current visible universe originated in a small (tiny)
>> region of the total structure, which might be infinite in extent, but flat
>> everywhere, even in our tiny region.
>>
>
> *Not to split hairs, but how can the tiny visible region also be flat and
> infinite in extent, if its age is finite? I can imagine the visible region
> to be asymptotically (but not mathematically) flat, and therefore finite in
> extent. AG *
>

I said that the total structure might be infinite in extent, not the region
that became our visible universe. Flatness is a mathematical property --
imagination readily fails to visualise these things.

Bruce

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Re: CMBR and Horizon Problem

[agrayson2000]

On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote:
>
>
>
> On 12/23/2018 4:47 PM, agrays...@gmail.com  wrote:
>
> *If by "flat", you mean mathematically flat, like a plane extending 
> infinitely in all directions, as opposed to asymptotically flat like a huge 
> and expanding sphere,  you have to reconcile an infinitesimally tiny 
> universe at the time of the BB, and simultaneously an infinitely large 
> universe extending infinitely in all directions. AG*
>
>
> All that's "infinitesimally tiny" is the visible universe.  You must know 
> that the Friedmann equation just defines the dynamics of a scale factor, 
> not a size.
>

*Are you claiming the visible universe at the BB was infinitesimally tiny, 
but the non visible part was infinitely large (mathematically flat), or 
huge (asymptotically flat)? AG *

>
> Brent 
>

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Re: CMBR and Horizon Problem

[agrayson2000]

On Monday, December 24, 2018 at 4:47:02 AM UTC, Bruce wrote:
>
> On Mon, Dec 24, 2018 at 3:33 PM > wrote:
>
>> On Monday, December 24, 2018 at 4:22:24 AM UTC, agrays...@gmail.com 
>> wrote:
>>>
>>> On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote:

 On 12/23/2018 4:47 PM, agrays...@gmail.com wrote:

 *If by "flat", you mean mathematically flat, like a plane extending 
 infinitely in all directions, as opposed to asymptotically flat like a 
 huge 
 and expanding sphere,  you have to reconcile an infinitesimally tiny 
 universe at the time of the BB, and simultaneously an infinitely large 
 universe extending infinitely in all directions. AG*


 All that's "infinitesimally tiny" is the visible universe.  You must 
 know that the Friedmann equation just defines the dynamics of a scale 
 factor, not a size.

>>>
>>> *Are you claiming the visible universe at the BB was infinitesimally 
>>> tiny, but the non visible part was infinitely large (mathematically flat), 
>>> or huge (asymptotically flat)? AG *
>>>
>>
>> *Bruce says the universe is always flat if k=1. How can it be everywhere 
>> flat if there's a region which is infinitely tiny; hence not flat in the 
>> visible region? How are we to imagine this? TIA, AG *
>>
>
> That's a bit confused. k=0 corresponds to a universe that is everywhere 
> flat (in space, but not necessarily in the time dimension - i.e., it might 
> be expanding. Our current visible universe originated in a small (tiny) 
> region of the total structure, which might be infinite in extent, but flat 
> everywhere, even in our tiny region.
>

*Not to split hairs, but how can the tiny visible region also be flat and 
infinite in extent, if its age is finite? I can imagine the visible region 
to be asymptotically (but not mathematically) flat, and therefore finite in 
extent. AG *

>
> Bruce
>

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Re: CMBR and Horizon Problem

[Bruce Kellett]

On Mon, Dec 24, 2018 at 3:33 PM  wrote:

> On Monday, December 24, 2018 at 4:22:24 AM UTC, agrays...@gmail.com wrote:
>>
>> On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote:
>>>
>>> On 12/23/2018 4:47 PM, agrays...@gmail.com wrote:
>>>
>>> *If by "flat", you mean mathematically flat, like a plane extending
>>> infinitely in all directions, as opposed to asymptotically flat like a huge
>>> and expanding sphere,  you have to reconcile an infinitesimally tiny
>>> universe at the time of the BB, and simultaneously an infinitely large
>>> universe extending infinitely in all directions. AG*
>>>
>>>
>>> All that's "infinitesimally tiny" is the visible universe.  You must
>>> know that the Friedmann equation just defines the dynamics of a scale
>>> factor, not a size.
>>>
>>
>> *Are you claiming the visible universe at the BB was infinitesimally
>> tiny, but the non visible part was infinitely large (mathematically flat),
>> or huge (asymptotically flat)? AG *
>>
>
> *Bruce says the universe is always flat if k=1. How can it be everywhere
> flat if there's a region which is infinitely tiny; hence not flat in the
> visible region? How are we to imagine this? TIA, AG *
>

That's a bit confused. k=0 corresponds to a universe that is everywhere
flat (in space, but not necessarily in the time dimension - i.e., it might
be expanding. Our current visible universe originated in a small (tiny)
region of the total structure, which might be infinite in extent, but flat
everywhere, even in our tiny region.

Bruce

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Re: CMBR and Horizon Problem

[agrayson2000]

On Monday, December 24, 2018 at 4:22:24 AM UTC, agrays...@gmail.com wrote:
>
>
>
> On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote:
>>
>>
>>
>> On 12/23/2018 4:47 PM, agrays...@gmail.com wrote:
>>
>> *If by "flat", you mean mathematically flat, like a plane extending 
>> infinitely in all directions, as opposed to asymptotically flat like a huge 
>> and expanding sphere,  you have to reconcile an infinitesimally tiny 
>> universe at the time of the BB, and simultaneously an infinitely large 
>> universe extending infinitely in all directions. AG*
>>
>>
>> All that's "infinitesimally tiny" is the visible universe.  You must know 
>> that the Friedmann equation just defines the dynamics of a scale factor, 
>> not a size.
>>
>
> *Are you claiming the visible universe at the BB was infinitesimally tiny, 
> but the non visible part was infinitely large (mathematically flat), or 
> huge (asymptotically flat)? AG *
>

*Bruce says the universe is always flat if k=1. How can it be everywhere 
flat if there's a region which is infinitely tiny; hence not flat in the 
visible region? How are we to imagine this? TIA, AG *

>
>
>> Brent 
>>
>

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Re: CMBR and Horizon Problem

[Brent Meeker]

On 12/23/2018 4:47 PM, agrayson2...@gmail.com wrote:
*If by "flat", you mean mathematically flat, like a plane extending 
infinitely in all directions, as opposed to asymptotically flat like a 
huge and expanding sphere,  you have to reconcile an infinitesimally 
tiny universe at the time of the BB, and simultaneously an infinitely 
large universe extending infinitely in all directions. AG*


All that's "infinitesimally tiny" is the visible universe.  You must 
know that the Friedmann equation just defines the dynamics of a scale 
factor, not a size.


Brent

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Re: CMBR and Horizon Problem

[agrayson2000]

On Sunday, December 23, 2018 at 10:38:00 PM UTC, Bruce wrote:
>
> On Mon, Dec 24, 2018 at 1:38 AM John Clark  > wrote:
>
>> On Sat, Dec 22, 2018 at 11:32 PM Bruce Kellett > > 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.
>

*If by "flat", you mean mathematically flat, like a plane extending 
infinitely in all directions, as opposed to asymptotically flat like a huge 
and expanding sphere,  you have to reconcile an infinitesimally tiny 
universe at the time of the BB, and simultaneously an infinitely large 
universe extending infinitely in all directions. AG*

>
>  
>
>> 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
>

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Re: CMBR and Horizon Problem

[Bruce Kellett]

On Mon, Dec 24, 2018 at 1:38 AM John Clark  wrote:

> On Sat, Dec 22, 2018 at 11:32 PM Bruce Kellett 
> 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

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Re: CMBR and Horizon Problem

[John Clark]

On Sat, Dec 22, 2018 at 11:32 PM Bruce Kellett 
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.

It would seem to me that if two theories can explain observations then the
one with the simpler initial conditions is the superior.

 John K Clark







>

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Re: CMBR and Horizon Problem

[agrayson2000]

On Sunday, December 23, 2018 at 3:27:35 AM UTC, agrays...@gmail.com wrote:
>
>
>
> On Sunday, December 23, 2018 at 3:04:07 AM UTC, Bruce wrote:
>>
>> On Sun, Dec 23, 2018 at 1:17 PM John Clark  wrote:
>>
>>> On Sat, Dec 22, 2018 at 6:46 AM  wrote:
>>>
>>> *> If the temperature was non uniform when the BB occurred, if it 
 occurred, why would a sudden increase in its volume, aka inflation, erase 
 or wash out those non uniformities?*

>>>
>>> Regardless of how non-uniform the entire early universe may have been if 
>>> you kept looking at smaller and smaller volumes you'd eventually find a 
>>> size where thing were pretty uniform.
>>>
>>
>> On what do you bas that assumption? Penrose makes the point that there is 
>> no reason to suppose that the initial state is not fractal -- grossly 
>> unsmooth on any scale, right down to the smallest!
>>  
>>
>>> If inflation theory is correct that small nearly uniform part of the 
>>> universe started to expand exponentially; that is to say it had a fixed 
>>> doubling time, every 10^-37 seconds the diameter of that small part of the 
>>> universe doubled, and in 10^-35 seconds it doubled a hundred times and 
>>> became our observable universe. It has continued to expand to this day but 
>>> at a much much more leisurely rate.
>>>
>>
>> It has been pointed out many times that inflation is a model in search of 
>> a problem to solve. Monopoles and flatness are not really problems, and 
>> inflation does not solve the smoothness problem - vide above.
>>
>
> *I've haven't resolved how inflation solves the smoothness problem (as 
> many claim) -- maybe it can't and thus is the cause of my puzzlement -- but 
> isn't the flatness problem a real problem that IS explained by inflation? 
> If not, why? AG *
>

*Agreed. My objection wrt flatness not worth a reply. The Oracle from 
Australia has spoken. AG *

>
>
>> Bruce
>>  
>>
>>>  
>>>
 > *OTOH, if the initial temperature were uniform, would that obviate 
 the need for inflation, or would non uniformities tend to become manifest 
 were it not for inflation?*

>>>  
>>> Without inflation its very hard to understand how the temperature could 
>>> be uniform because there wasn't enough time for the temperature to 
>>> equalize, the distance parts of the universe were neven is causal comtact 
>>> and yet they are at the same temperature to one part in 100,000. 
>>>
>>> John K Clark
>>>
>>

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Re: CMBR and Horizon Problem

[Bruce Kellett]

On Sun, Dec 23, 2018 at 3:05 PM John Clark  wrote:

> On Sat, Dec 22, 2018 at 10:04 PM Bruce Kellett 
> wrote:
>
> >>Regardless of how non-uniform the entire early universe may have been
>>> if you kept looking at smaller and smaller volumes you'd eventually find a
>>> size where thing were pretty uniform.
>>>
>>
>> *> On what do you bas that assumption? *
>>
>
> Observational evidence. We know that the temperature 13.8 light years to
> your left and 13.8 light years to your right differ by less than one part
> in 100,000. The universe is only 13.8 billion years old so I don't see how
> they came to thermal equilibrium (or nearly so) if inflation didn't
> happen.
>
>
>
>> > *Penrose makes the point that there is no reason to suppose that the
>> initial state is not fractal -- grossly unsmooth on any scale, right down
>> to the smallest!*
>>
>
>
> If you examine a copper plate today its temperature does not display a
> fractal pattern, in fact I can't think of anything that does, so something
> certainly changed, if not inflation then what?. And if the early universe
> was as  Penrose said the universe once was then I don't see how complex
> structures like you and me that are capable of making calculations could
> ever make an appearance.
>

The point is that inflation only solves the problem given certain initial
conditions. We have no independent knowledge of those initial conditions,
so it could well be that the initial condition was that everything was
always at a uniform temperature, and there was no need for something, such
as inflation, to render the CMB uniform everywhere.

Bruce

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Re: CMBR and Horizon Problem

[John Clark]

On Sat, Dec 22, 2018 at 10:04 PM Bruce Kellett 
wrote:

>>Regardless of how non-uniform the entire early universe may have been if
>> you kept looking at smaller and smaller volumes you'd eventually find a
>> size where thing were pretty uniform.
>>
>
> *> On what do you bas that assumption? *
>

Observational evidence. We know that the temperature 13.8 light years to
your left and 13.8 light years to your right differ by less than one part
in 100,000. The universe is only 13.8 billion years old so I don't see how
they came to thermal equilibrium (or nearly so) if inflation didn't happen.



> > *Penrose makes the point that there is no reason to suppose that the
> initial state is not fractal -- grossly unsmooth on any scale, right down
> to the smallest!*
>


If you examine a copper plate today its temperature does not display a
fractal pattern, in fact I can't think of anything that does, so something
certainly changed, if not inflation then what?. And if the early universe
was as  Penrose said the universe once was then I don't see how complex
structures like you and me that are capable of making calculations could
ever make an appearance.

John K Clark

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Re: CMBR and Horizon Problem

[agrayson2000]

On Sunday, December 23, 2018 at 3:04:07 AM UTC, Bruce wrote:
>
> On Sun, Dec 23, 2018 at 1:17 PM John Clark  > wrote:
>
>> On Sat, Dec 22, 2018 at 6:46 AM > 
>> wrote:
>>
>> *> If the temperature was non uniform when the BB occurred, if it 
>>> occurred, why would a sudden increase in its volume, aka inflation, erase 
>>> or wash out those non uniformities?*
>>>
>>
>> Regardless of how non-uniform the entire early universe may have been if 
>> you kept looking at smaller and smaller volumes you'd eventually find a 
>> size where thing were pretty uniform.
>>
>
> On what do you bas that assumption? Penrose makes the point that there is 
> no reason to suppose that the initial state is not fractal -- grossly 
> unsmooth on any scale, right down to the smallest!
>  
>
>> If inflation theory is correct that small nearly uniform part of the 
>> universe started to expand exponentially; that is to say it had a fixed 
>> doubling time, every 10^-37 seconds the diameter of that small part of the 
>> universe doubled, and in 10^-35 seconds it doubled a hundred times and 
>> became our observable universe. It has continued to expand to this day but 
>> at a much much more leisurely rate.
>>
>
> It has been pointed out many times that inflation is a model in search of 
> a problem to solve. Monopoles and flatness are not really problems, and 
> inflation does not solve the smoothness problem - vide above.
>

*I've haven't resolved how inflation solves the smoothness problem (as many 
claim) -- maybe it can't and thus is the cause of my puzzlement -- but 
isn't the flatness problem a real problem that IS explained by inflation? 
If not, why? AG *

>
> Bruce
>  
>
>>  
>>
>>> > *OTOH, if the initial temperature were uniform, would that obviate 
>>> the need for inflation, or would non uniformities tend to become manifest 
>>> were it not for inflation?*
>>>
>>  
>> Without inflation its very hard to understand how the temperature could 
>> be uniform because there wasn't enough time for the temperature to 
>> equalize, the distance parts of the universe were neven is causal comtact 
>> and yet they are at the same temperature to one part in 100,000. 
>>
>> John K Clark
>>
>

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Re: CMBR and Horizon Problem

[Bruce Kellett]

On Sun, Dec 23, 2018 at 1:17 PM John Clark  wrote:

> On Sat, Dec 22, 2018 at 6:46 AM  wrote:
>
> *> If the temperature was non uniform when the BB occurred, if it
>> occurred, why would a sudden increase in its volume, aka inflation, erase
>> or wash out those non uniformities?*
>>
>
> Regardless of how non-uniform the entire early universe may have been if
> you kept looking at smaller and smaller volumes you'd eventually find a
> size where thing were pretty uniform.
>

On what do you bas that assumption? Penrose makes the point that there is
no reason to suppose that the initial state is not fractal -- grossly
unsmooth on any scale, right down to the smallest!


> If inflation theory is correct that small nearly uniform part of the
> universe started to expand exponentially; that is to say it had a fixed
> doubling time, every 10^-37 seconds the diameter of that small part of the
> universe doubled, and in 10^-35 seconds it doubled a hundred times and
> became our observable universe. It has continued to expand to this day but
> at a much much more leisurely rate.
>

It has been pointed out many times that inflation is a model in search of a
problem to solve. Monopoles and flatness are not really problems, and
inflation does not solve the smoothness problem - vide above.

Bruce


>
>
>> > *OTOH, if the initial temperature were uniform, would that obviate the
>> need for inflation, or would non uniformities tend to become manifest were
>> it not for inflation?*
>>
>
> Without inflation its very hard to understand how the temperature could be
> uniform because there wasn't enough time for the temperature to equalize,
> the distance parts of the universe were neven is causal comtact and yet
> they are at the same temperature to one part in 100,000.
>
> John K Clark
>

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Re: CMBR and Horizon Problem

[agrayson2000]

On Sunday, December 23, 2018 at 2:17:14 AM UTC, John Clark wrote:
>
> On Sat, Dec 22, 2018 at 6:46 AM > wrote:
>
> *> If the temperature was non uniform when the BB occurred, if it 
>> occurred, why would a sudden increase in its volume, aka inflation, erase 
>> or wash out those non uniformities?*
>>
>
> Regardless of how non-uniform the entire early universe may have been if 
> you kept looking at smaller and smaller volumes you'd eventually find a 
> size where thing were pretty uniform.  If inflation theory is correct that 
> small nearly uniform part of the universe started to expand exponentially; 
> that 
> is to say it had a fixed doubling time, every 10^-37 seconds the diameter 
> of that small part of the universe doubled, and in 10^-35 seconds it 
> doubled a hundred times and became our observable universe. It has continued 
> to expand to this day but at a much much more leisurely rate. 
>  
>
>> > *OTOH, if the initial temperature were uniform, would that obviate the 
>> need for inflation, or would non uniformities tend to become manifest were 
>> it not for inflation?*
>>
>  
> Without inflation its very hard to understand how the temperature could be 
> uniform because there wasn't enough time for the temperature to equalize, 
> the distance parts of the universe were neven is causal comtact and yet 
> they are at the same temperature to one part in 100,000. 
>

*CMIIAW, but you're assuming the initial BB temperature was non uniform and 
inflation is needed to get the uniform temperature we observe. The problem 
with this is that (by applying your argument in first paragraph) one would 
expect an infinitesimally small universe to have a uniform temperature. 
Thus, inflation doesn't seem necessary to get to uniformity. It only serves 
to explain the flatness. BTW, how is the curvature of the universe 
measured? TIA, AG *

>
> John K Clark
>
>  
>

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Re: CMBR and Horizon Problem

[agrayson2000]

On Saturday, December 22, 2018 at 10:08:37 PM UTC, Brent wrote:
>
>
>
> On 12/22/2018 3:46 AM, agrays...@gmail.com  wrote: 
> > If the temperature was non uniform when the BB occurred, if it 
> > occurred, why would a sudden increase in its volume, aka inflation, 
> > erase or wash out those non uniformities? ISTM, it would preserve them. 
>
> It might preserve them, but it would push them beyond the visible part 
> of the universe. 
>
> > OTOH, if the initial temperature were uniform, would that obviate the 
> > need for inflation, or would non uniformities tend to become manifest 
> > were it not for inflation? TIA, AG 
>
> No, Guth actually proposed inflation as a way to explain the absence of 
> magnetic monopoles and the apparent spatial flatness of the universe. 
>

*You joggled my memory. Usually, or often, the case is made that inflation 
explains*

*the uniformity of the CMBR temperature, which is also called the Horizon 
Problem. *

*How does it do that? What assumptions are made about initial BB 
temperature to *
*cause inflation to be a plausible explanation? TIA, AG*

>
> Brent 
>

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Re: CMBR and Horizon Problem

[John Clark]

On Sat, Dec 22, 2018 at 6:46 AM  wrote:

*> If the temperature was non uniform when the BB occurred, if it occurred,
> why would a sudden increase in its volume, aka inflation, erase or wash out
> those non uniformities?*
>

Regardless of how non-uniform the entire early universe may have been if
you kept looking at smaller and smaller volumes you'd eventually find a
size where thing were pretty uniform.  If inflation theory is correct that
small nearly uniform part of the universe started to expand exponentially; that
is to say it had a fixed doubling time, every 10^-37 seconds the diameter
of that small part of the universe doubled, and in 10^-35 seconds it
doubled a hundred times and became our observable universe. It has continued
to expand to this day but at a much much more leisurely rate.


> > *OTOH, if the initial temperature were uniform, would that obviate the
> need for inflation, or would non uniformities tend to become manifest were
> it not for inflation?*
>

Without inflation its very hard to understand how the temperature could be
uniform because there wasn't enough time for the temperature to equalize,
the distance parts of the universe were neven is causal comtact and yet
they are at the same temperature to one part in 100,000.

John K Clark

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Re: CMBR and Horizon Problem

[Brent Meeker]

On 12/22/2018 3:46 AM, agrayson2...@gmail.com wrote:
If the temperature was non uniform when the BB occurred, if it 
occurred, why would a sudden increase in its volume, aka inflation, 
erase or wash out those non uniformities? ISTM, it would preserve them.


It might preserve them, but it would push them beyond the visible part 
of the universe.


OTOH, if the initial temperature were uniform, would that obviate the 
need for inflation, or would non uniformities tend to become manifest 
were it not for inflation? TIA, AG


No, Guth actually proposed inflation as a way to explain the absence of 
magnetic monopoles and the apparent spatial flatness of the universe.


Brent

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Re: CMBR and Horizon Problem

[agrayson2000]

On Saturday, December 22, 2018 at 11:46:18 AM UTC, agrays...@gmail.com 
wrote:
>
> If the temperature was non uniform when the BB occurred, if it occurred, 
> why would a sudden increase in its volume, aka inflation, erase or wash out 
> those non uniformities? ISTM, it would preserve them. OTOH, if the initial 
> temperature were uniform, would that obviate the need for inflation, or 
> would non uniformities tend to become manifest were it not for inflation? 
> TIA, AG
>

IOW, what is the initial temperature condition assumed for the BB, uniform 
or non uniform, for which inflation is alleged to be the solution for? If 
initially uniform, is it assumed that asymmetries would arise were it not 
for inflation? If so, how would inflation prevent such asymmetries from 
arising? If initially non-uniform, is it believed symmetry required 
inflation, and if so, why? In this case, I don't see why a sudden inflation 
would not simply retain the asymmetry.TIA, AG

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CMBR and Horizon Problem

[agrayson2000]

If the temperature was non uniform when the BB occurred, if it occurred, 
why would a sudden increase in its volume, aka inflation, erase or wash out 
those non uniformities? ISTM, it would preserve them. OTOH, if the initial 
temperature were uniform, would that obviate the need for inflation, or 
would non uniformities tend to become manifest were it not for inflation? 
TIA, AG

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