Expansion rate of the very early universe

[Alan Grayson]

Given the fact that light from very distant galaxies is hugely red-shifted, and the general belief that light we're observing today from those distant galaxies, was emitted when the universe was very young, one would conclude that the rate of expansion at that time was huge. But Clark disputes this conclusion. He claims the opposite; that the rate of expansion in the very early universe was exceedingly SLOW. If that's the case, can we conclude that the theory of Inflation must be false, insofar as it alleges a huge initial expansion rate to account for the observed uniformity of the current universe? Moreover, Hubble's law confirms that as we go back in time, the universe was expanding faster than it is today, again apparently confirming the Inflation theory of a very high initial rate of expansion (ignoring recent findings the the rate of expansion is iagain ncreasing). AG

[Brent Meeker]

Galaxies formed waaay after the Big Bang and we can't actually observe anything earlier than the recombination around 400,000yr after the BB.

I don't know what JKC said about the speed of early expansion, but it seems to be increasing so it will be faster in the future than it was in the past. 



Brent

On 7/14/2025 7:30 PM, Alan Grayson wrote:

Given the fact that light from very distant galaxies is hugely red-shifted, and the general belief that light we're observing today from those distant galaxies, was emitted when the universe was very young, one would conclude that the rate of expansion at that time was huge. But Clark disputes this conclusion. He claims the opposite; that the rate of expansion in the very early universe was exceedingly SLOW. If that's the case, can we conclude that the theory of Inflation must be false, insofar as it alleges a huge initial expansion rate to account for the observed uniformity of the current universe? Moreover, Hubble's law confirms that as we go back in time, the universe was expanding faster than it is today, again apparently confirming the Inflation theory of a very high initial rate of expansion (ignoring recent findings the the rate of expansion is iagain ncreasing). AG --
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[Alan Grayson]

On Monday, July 14, 2025 at 10:52:44 PM UTC-6 Brent Meeker wrote:

Galaxies formed waaay after the Big Bang and we can't actually observe anything earlier than the recombination around 400,000yr after the BB.

I am aware of that. Nevertheless, the red shift of distant galaxies indicates that they were receding at huge velocities, obviously after they were formed. According to Inflation theory, there was a HUGE, HUGE expansion immediately after the BB, which lasted for a TINY, TINY fraction of the first second. This is generally accepted within the physics community since it answers some pressing issues such as the uniformity of the CMB. AG

I don't know what JKC said about the speed of early expansion, but it seems to be increasing so it will be faster in the future than it was in the past. 

He claimed the early rate of expansion was exceedingly slow, and that the red shift we now observes indicates the current receding velocity. AG 

[John Clark]

On Mon, Jul 14, 2025 at 10:30 PM Alan Grayson <agrays...@gmail.com> wrote:

> Given the fact that light from very distant galaxies is hugely red-shifted, and the general belief that light we're observing today from those distant galaxies, was emitted when the universe was very young, one would conclude that the rate of expansion at that time was huge. But Clark disputes this conclusion. He claims the opposite; that the rate of expansion in the very early universe was exceedingly SLOW. But Clark disputes this conclusion. He claims the opposite; that the rate of expansion in the very early universe was exceedingly SLOW.

But Clark has never made that claim, and I should know because I am the world's greatest expert on that man. Galaxies in the past were expanding slower from each other than they are today, but that was NOT a time when the universe was "very young". Galaxies didn't even start to form until about 100 million years after the Big Bang. 

 

> If that's the case, can we conclude that the theory of Inflation must be false, 

That is a strange conclusion to make given the fact that if the theory of Inflation is correct then the rate of expansion of the very early universe was approximately 10^52 (10,000 trillion trillion trillion trillion) times faster than it is today. 

John K Clark    See what's on my new list at  Extropolis

r55

[John Clark]

On Tue, Jul 15, 2025 at 2:13 AM Alan Grayson <agrays...@gmail.com> wrote:

> According to Inflation theory, there was a HUGE, HUGE expansion immediately after the BB, which lasted for a TINY, TINY fraction of the first second. 

 

If inflation theory is correct then the universe became immensely larger in a very short amount of time, the exact figure is unknown but the lower limit is that in just 10^-32 seconds the volume of the universe became 10^26 (100 trillion trillion) times larger. However it's entirely possible that the period of inflation lasted longer than 10^-32 seconds and thus the volume of the universe became even larger than 10^26.

[Alan Grayson]

On Tuesday, July 15, 2025 at 4:46:03 AM UTC-6 John Clark wrote:

On Mon, Jul 14, 2025 at 10:30 PM Alan Grayson <agrays...@gmail.com> wrote:

> Given the fact that light from very distant galaxies is hugely red-shifted, and the general belief that light we're observing today from those distant galaxies, was emitted when the universe was very young, one would conclude that the rate of expansion at that time was huge. But Clark disputes this conclusion. He claims the opposite; that the rate of expansion in the very early universe was exceedingly SLOW. But Clark disputes this conclusion. He claims the opposite; that the rate of expansion in the very early universe was exceedingly SLOW.

But Clark has never made that claim, and I should know because I am the world's greatest expert on that man. Galaxies in the past were expanding slower from each other than they are today,

Yes. AG

but that was NOT a time when the universe was "very young". Galaxies didn't even start to form until about 100 million years after the Big Bang. 

"Very young" is subjective. When I have time, I'll search for your misleading claim. AG

 

> If that's the case, can we conclude that the theory of Inflation must be false, 

That is a strange conclusion to make given the fact that if the theory of Inflation is correct then the rate of expansion of the very early universe was approximately 10^52 (10,000 trillion trillion trillion trillion) times faster than it is today. 

Not at all strange. If the universe was expanding very slowing immediately after the BB, it would contradict Inflation theory. AG 

[Quentin Anciaux]

All those moments will be lost in time, like tears in rain. (Roy Batty/Rutger Hauer)

Le mar. 15 juil. 2025, 15:37, Alan Grayson <agrays...@gmail.com> a écrit :

On Tuesday, July 15, 2025 at 4:46:03 AM UTC-6 John Clark wrote:

On Mon, Jul 14, 2025 at 10:30 PM Alan Grayson <agrays...@gmail.com> wrote:

> Given the fact that light from very distant galaxies is hugely red-shifted, and the general belief that light we're observing today from those distant galaxies, was emitted when the universe was very young, one would conclude that the rate of expansion at that time was huge. But Clark disputes this conclusion. He claims the opposite; that the rate of expansion in the very early universe was exceedingly SLOW. But Clark disputes this conclusion. He claims the opposite; that the rate of expansion in the very early universe was exceedingly SLOW.

But Clark has never made that claim, and I should know because I am the world's greatest expert on that man. Galaxies in the past were expanding slower from each other than they are today,

Yes. AG

but that was NOT a time when the universe was "very young". Galaxies didn't even start to form until about 100 million years after the Big Bang. 

"Very young" is subjective. When I have time, I'll search for your misleading claim. AG

It's incredible how you never ever consider the possibility of having misread or misunderstood something. It's always the other person at fault. JC never made that claim, and instead of vaguely promising to "search for it later", you should either cite it now or refrain from making accusations. Truth isn't whatever you feel it is, it's in the actual words, not your projections.

Quentin 

 

> If that's the case, can we conclude that the theory of Inflation must be false, 

That is a strange conclusion to make given the fact that if the theory of Inflation is correct then the rate of expansion of the very early universe was approximately 10^52 (10,000 trillion trillion trillion trillion) times faster than it is today. 

Not at all strange. If the universe was expanding very slowing immediately after the BB, it would contradict Inflation theory. AG 

John K Clark    See what's on my new list at  Extropolis

r55

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[Alan Grayson]

On Tuesday, July 15, 2025 at 11:25:12 AM UTC-6 Quentin Anciaux wrote:

All those moments will be lost in time, like tears in rain. (Roy Batty/Rutger Hauer)

Le mar. 15 juil. 2025, 15:37, Alan Grayson <agrays...@gmail.com> a écrit :

On Tuesday, July 15, 2025 at 4:46:03 AM UTC-6 John Clark wrote:

On Mon, Jul 14, 2025 at 10:30 PM Alan Grayson <agrays...@gmail.com> wrote:

> Given the fact that light from very distant galaxies is hugely red-shifted, and the general belief that light we're observing today from those distant galaxies, was emitted when the universe was very young, one would conclude that the rate of expansion at that time was huge. But Clark disputes this conclusion. He claims the opposite; that the rate of expansion in the very early universe was exceedingly SLOW. But Clark disputes this conclusion. He claims the opposite; that the rate of expansion in the very early universe was exceedingly SLOW.

But Clark has never made that claim, and I should know because I am the world's greatest expert on that man. Galaxies in the past were expanding slower from each other than they are today,

Yes. AG

but that was NOT a time when the universe was "very young". Galaxies didn't even start to form until about 100 million years after the Big Bang. 

"Very young" is subjective. When I have time, I'll search for your misleading claim. AG

It's incredible how you never ever consider the possibility of having misread or misunderstood something. It's always the other person at fault. JC never made that claim, and instead of vaguely promising to "search for it later", you should either cite it now or refrain from making accusations. Truth isn't whatever you feel it is, it's in the actual words, not your projections.

Quentin 

I asked him about that at the time, more than once, and he seemed to affirm what I alleged above. But right now, my computer was hacked, so my priority has been to remove the hackers. I suggest you mind your own business, and I will try to find his claim. Like I said, when I have the time. Incidentally, I can and do admit my mistakes, so take this advice; never say never. AG  

[Quentin Anciaux]

All those moments will be lost in time, like tears in rain. (Roy Batty/Rutger Hauer)

Le mar. 15 juil. 2025, 20:23, Alan Grayson <agrays...@gmail.com> a écrit :

On Tuesday, July 15, 2025 at 11:25:12 AM UTC-6 Quentin Anciaux wrote:

All those moments will be lost in time, like tears in rain. (Roy Batty/Rutger Hauer)

Le mar. 15 juil. 2025, 15:37, Alan Grayson <agrays...@gmail.com> a écrit :

On Tuesday, July 15, 2025 at 4:46:03 AM UTC-6 John Clark wrote:

On Mon, Jul 14, 2025 at 10:30 PM Alan Grayson <agrays...@gmail.com> wrote:

> Given the fact that light from very distant galaxies is hugely red-shifted, and the general belief that light we're observing today from those distant galaxies, was emitted when the universe was very young, one would conclude that the rate of expansion at that time was huge. But Clark disputes this conclusion. He claims the opposite; that the rate of expansion in the very early universe was exceedingly SLOW. But Clark disputes this conclusion. He claims the opposite; that the rate of expansion in the very early universe was exceedingly SLOW.

But Clark has never made that claim, and I should know because I am the world's greatest expert on that man. Galaxies in the past were expanding slower from each other than they are today,

Yes. AG

but that was NOT a time when the universe was "very young". Galaxies didn't even start to form until about 100 million years after the Big Bang. 

"Very young" is subjective. When I have time, I'll search for your misleading claim. AG

It's incredible how you never ever consider the possibility of having misread or misunderstood something. It's always the other person at fault. JC never made that claim, and instead of vaguely promising to "search for it later", you should either cite it now or refrain from making accusations. Truth isn't whatever you feel it is, it's in the actual words, not your projections.

Quentin 

I asked him about that at the time, more than once, and he seemed to affirm what I alleged above. But right now, my computer was hacked, so my priority has been to remove the hackers. I suggest you mind your own business, and I will try to find his claim. Like I said, when I have the time. Incidentally, I can and do admit my mistakes, so take this advice; never say never. AG  

Didn't happen till now..

 

> If that's the case, can we conclude that the theory of Inflation must be false, 

That is a strange conclusion to make given the fact that if the theory of Inflation is correct then the rate of expansion of the very early universe was approximately 10^52 (10,000 trillion trillion trillion trillion) times faster than it is today. 

Not at all strange. If the universe was expanding very slowing immediately after the BB, it would contradict Inflation theory. AG 

John K Clark    See what's on my new list at  Extropolis

r55

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[John Clark]

On Tue, Jul 15, 2025 at 2:23 PM Alan Grayson <agrays...@gmail.com> wrote:

>> It's incredible how you never ever consider the possibility of having misread or misunderstood something. It's always the other person at fault. JC never made that claim, and instead of vaguely promising to "search for it later", you should either cite it now or refrain from making accusations. Truth isn't whatever you feel it is, it's in the actual words, not your projections.

Quentin 

> I asked him about that at the time, more than once, and he seemed to affirm what I alleged above.

BULLSHIT! The theory of inflation is about the HUGE acceleration that occurred  a tiny fraction of a second after the Big Bang, it has nothing to say about dark energy and the fact that the universe is currently undergoing a very slight acceleration that is trillions and trillions of times less then what inflation theory is talking about. It's conceivable that the two things might be connected in some way, but most think they are not.    

 

> But right now, my computer was hacked,

Did your dog eat your homework too? 

John K Clark    See what's on my new list at  Extropolis

eew

[Brent Meeker]

On 7/14/2025 11:13 PM, Alan Grayson wrote:

On Monday, July 14, 2025 at 10:52:44 PM UTC-6 Brent Meeker wrote:

Galaxies formed waaay after the Big Bang and we can't actually observe anything earlier than the recombination around 400,000yr after the BB.

I am aware of that. Nevertheless, the red shift of distant galaxies indicates that they were receding at huge velocities, obviously after they were formed. 

They're receding at huge velocities from us...or are we receding at huge velocities from them.

According to Inflation theory, there was a HUGE, HUGE expansion immediately after the BB, which lasted for a TINY, TINY fraction of the first second. This is generally accepted within the physics community since it answers some pressing issues such as the uniformity of the CMB. AG

I don't know what JKC said about the speed of early expansion, but it seems to be increasing so it will be faster in the future than it was in the past. 

He claimed the early rate of expansion was exceedingly slow, and that the red shift we now observes indicates the current receding velocity. AG 

You do realize don't you that the uniform Hubble expansion means the further away you are from X, the faster you're "receding" from X.  And since it's been a long time since galaxies formed they used to be closer together and hence were not "receding" from one another as fast, even if the expansion of the universe (the Hubble constant) was the same.  I think you're confused about "expansion rate" (the Hubble constant) vs "recession rate".

Brent

Brent

On 7/14/2025 7:30 PM, Alan Grayson wrote:

Given the fact that light from very distant galaxies is hugely red-shifted, and the general belief that light we're observing today from those distant galaxies, was emitted when the universe was very young, one would conclude that the rate of expansion at that time was huge. But Clark disputes this conclusion. He claims the opposite; that the rate of expansion in the very early universe was exceedingly SLOW. If that's the case, can we conclude that the theory of Inflation must be false, insofar as it alleges a huge initial expansion rate to account for the observed uniformity of the current universe? Moreover, Hubble's law confirms that as we go back in time, the universe was expanding faster than it is today, again apparently confirming the Inflation theory of a very high initial rate of expansion (ignoring recent findings the the rate of expansion is iagain ncreasing). AG 

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[Alan Grayson]

On Tuesday, July 15, 2025 at 1:37:35 PM UTC-6 Brent Meeker wrote:

On 7/14/2025 11:13 PM, Alan Grayson wrote:

On Monday, July 14, 2025 at 10:52:44 PM UTC-6 Brent Meeker wrote:

Galaxies formed waaay after the Big Bang and we can't actually observe anything earlier than the recombination around 400,000yr after the BB.

I am aware of that. Nevertheless, the red shift of distant galaxies indicates that they were receding at huge velocities, obviously after they were formed. 

They're receding at huge velocities from us...or are we receding at huge velocities from them.

According to Inflation theory, there was a HUGE, HUGE expansion immediately after the BB, which lasted for a TINY, TINY fraction of the first second. This is generally accepted within the physics community since it answers some pressing issues such as the uniformity of the CMB. AG

I don't know what JKC said about the speed of early expansion, but it seems to be increasing so it will be faster in the future than it was in the past. 

He claimed the early rate of expansion was exceedingly slow, and that the red shift we now observes indicates the current receding velocity. AG 

You do realize don't you that the uniform Hubble expansion means the further away you are from X, the faster you're "receding" from X.  And since it's been a long time since galaxies formed they used to be closer together and hence were not "receding" from one another as fast, even if the expansion of the universe (the Hubble constant) was the same. 

Yes, I am aware of these facts. But my problem is that the light coming from those galaxies is interpreted to mean they are being observed as they existed billions of years ago, whereas the recessional velocity is occurring now and is essentially dependent on geometry; that is, if we imagine a spherically shaped universe and two separated galaxies on its expanding equator, the farther way these galaxies are separated, the faster they are receding from each other. And that's happening now. So how do you reconcile what's happening now, with what the red shift indicates occurred in the distant past? AG

I think you're confused about "expansion rate" (the Hubble constant) vs "recession rate".

Brent

Brent

On 7/14/2025 7:30 PM, Alan Grayson wrote:

Given the fact that light from very distant galaxies is hugely red-shifted, and the general belief that light we're observing today from those distant galaxies, was emitted when the universe was very young, one would conclude that the rate of expansion at that time was huge. But Clark disputes this conclusion. He claims the opposite; that the rate of expansion in the very early universe was exceedingly SLOW. If that's the case, can we conclude that the theory of Inflation must be false, insofar as it alleges a huge initial expansion rate to account for the observed uniformity of the current universe? Moreover, Hubble's law confirms that as we go back in time, the universe was expanding faster than it is today, again apparently confirming the Inflation theory of a very high initial rate of expansion (ignoring recent findings the rate of expansion is again increasing). AG 

[Alan Grayson]

On Tuesday, July 15, 2025 at 11:25:12 AM UTC-6 Quentin Anciaux wrote:

All those moments will be lost in time, like tears in rain. (Roy Batty/Rutger Hauer)

Le mar. 15 juil. 2025, 15:37, Alan Grayson <agrays...@gmail.com> a écrit :

On Tuesday, July 15, 2025 at 4:46:03 AM UTC-6 John Clark wrote:

On Mon, Jul 14, 2025 at 10:30 PM Alan Grayson <agrays...@gmail.com> wrote:

> Given the fact that light from very distant galaxies is hugely red-shifted, and the general belief that light we're observing today from those distant galaxies, was emitted when the universe was very young, one would conclude that the rate of expansion at that time was huge. But Clark disputes this conclusion. He claims the opposite; that the rate of expansion in the very early universe was exceedingly SLOW. But Clark disputes this conclusion. He claims the opposite; that the rate of expansion in the very early universe was exceedingly SLOW.

But Clark has never made that claim, and I should know because I am the world's greatest expert on that man. Galaxies in the past were expanding slower from each other than they are today,

Yes. AG

but that was NOT a time when the universe was "very young". Galaxies didn't even start to form until about 100 million years after the Big Bang. 

"Very young" is subjective. When I have time, I'll search for your misleading claim. AG

It's incredible how you never ever consider the possibility of having misread or misunderstood something. It's always the other person at fault. JC never made that claim, and instead of vaguely promising to "search for it later", you should either cite it now or refrain from making accusations. Truth isn't whatever you feel it is, it's in the actual words, not your projections.

Quentin 

That's far, very far from an objective reading of my views. I usually use the word "seems" to indicate that my interpretation might be mistaken. In any event, if you're interested in Clark's view, which seems ambiguous, review again his posts on the Hubble thread, and let me know what you think he means. Of course, the expansion of the universe was slower following Inflation when the galaxies formed, starting around 380,000 years after the BB, but how can the red shift of distant galaxies NOT tell us about their recessional velocity in the distant past, which is what Clark seems to claim? He claims it only tells us how much the universe has expanded since their formation when photon frequency shifted from UV to red. But distant galaxies are receding rapidly NOW? Is there no red shift from that present recession? What the measured red shift tell us is not at all clear, at least to me. AG

 

> If that's the case, can we conclude that the theory of Inflation must be false, 

That is a strange conclusion to make given the fact that if the theory of Inflation is correct then the rate of expansion of the very early univese was approximately 10^52 (10,000 trillion trillion trillion trillion) times faster than it is today.   

[Alan Grayson]

On Wednesday, July 16, 2025 at 6:55:37 PM UTC-6 Alan Grayson wrote:

On Tuesday, July 15, 2025 at 11:25:12 AM UTC-6 Quentin Anciaux wrote:

All those moments will be lost in time, like tears in rain. (Roy Batty/Rutger Hauer)

Le mar. 15 juil. 2025, 15:37, Alan Grayson <agrays...@gmail.com> a écrit :

On Tuesday, July 15, 2025 at 4:46:03 AM UTC-6 John Clark wrote:

On Mon, Jul 14, 2025 at 10:30 PM Alan Grayson <agrays...@gmail.com> wrote:

> Given the fact that light from very distant galaxies is hugely red-shifted, and the general belief that light we're observing today from those distant galaxies, was emitted when the universe was very young, one would conclude that the rate of expansion at that time was huge. But Clark disputes this conclusion. He claims the opposite; that the rate of expansion in the very early universe was exceedingly SLOW. But Clark disputes this conclusion. He claims the opposite; that the rate of expansion in the very early universe was exceedingly SLOW.

But Clark has never made that claim, and I should know because I am the world's greatest expert on that man. Galaxies in the past were expanding slower from each other than they are today,

Yes. AG

but that was NOT a time when the universe was "very young". Galaxies didn't even start to form until about 100 million years after the Big Bang. 

"Very young" is subjective. When I have time, I'll search for your misleading claim. AG

It's incredible how you never ever consider the possibility of having misread or misunderstood something. It's always the other person at fault. JC never made that claim, and instead of vaguely promising to "search for it later", you should either cite it now or refrain from making accusations. Truth isn't whatever you feel it is, it's in the actual words, not your projections.

Quentin 

That's far, very far from an objective reading of my views. I usually use the word "seems" to indicate that my interpretation might be mistaken. In any event, if you're interested in Clark's view, which seems ambiguous, review again his posts on the Hubble thread, and let me know what you think he means. Of course, the expansion of the universe was slower following Inflation when the galaxies formed, starting around 380,000 years after the BB, but how can the red shift of distant galaxies NOT tell us about their recessional velocity in the distant past, which is what Clark seems to claim? He claims it only tells us how much the universe has expanded since their formation when photon frequency shifted from UV to red. But distant galaxies are receding rapidly NOW? Is there no red shift from that present recession? What the measured red shift tell us is not at all clear, at least to me. AG

Strike out question mark after NOW. AG 

[Quentin Anciaux]

All those moments will be lost in time, like tears in rain. (Roy Batty/Rutger Hauer)

Le jeu. 17 juil. 2025, 02:55, Alan Grayson <agrays...@gmail.com> a écrit :

On Tuesday, July 15, 2025 at 11:25:12 AM UTC-6 Quentin Anciaux wrote:

All those moments will be lost in time, like tears in rain. (Roy Batty/Rutger Hauer)

Le mar. 15 juil. 2025, 15:37, Alan Grayson <agrays...@gmail.com> a écrit :

On Tuesday, July 15, 2025 at 4:46:03 AM UTC-6 John Clark wrote:

On Mon, Jul 14, 2025 at 10:30 PM Alan Grayson <agrays...@gmail.com> wrote:

> Given the fact that light from very distant galaxies is hugely red-shifted, and the general belief that light we're observing today from those distant galaxies, was emitted when the universe was very young, one would conclude that the rate of expansion at that time was huge. But Clark disputes this conclusion. He claims the opposite; that the rate of expansion in the very early universe was exceedingly SLOW. But Clark disputes this conclusion. He claims the opposite; that the rate of expansion in the very early universe was exceedingly SLOW.

But Clark has never made that claim, and I should know because I am the world's greatest expert on that man. Galaxies in the past were expanding slower from each other than they are today,

Yes. AG

but that was NOT a time when the universe was "very young". Galaxies didn't even start to form until about 100 million years after the Big Bang. 

"Very young" is subjective. When I have time, I'll search for your misleading claim. AG

It's incredible how you never ever consider the possibility of having misread or misunderstood something. It's always the other person at fault. JC never made that claim, and instead of vaguely promising to "search for it later", you should either cite it now or refrain from making accusations. Truth isn't whatever you feel it is, it's in the actual words, not your projections.

Quentin 

That's far, very far from an objective reading of my views. I usually use the word "seems" to indicate that my interpretation might be mistaken. In any event, if you're interested in Clark's view, which seems ambiguous, review again his posts on the Hubble thread, and let me know what you think he means. Of course, the expansion of the universe was slower following Inflation when the galaxies formed, starting around 380,000 years after the BB, but how can the red shift of distant galaxies NOT tell us about their recessional velocity in the distant past, which is what Clark seems to claim? He claims it only tells us how much the universe has expanded since their formation when photon frequency shifted from UV to red. But distant galaxies are receding rapidly NOW? Is there no red shift from that present recession?

The light we see now was emitted billions of years ago, when those galaxies were much closer. The redshift tells us how much the universe has expanded since then.

But from that redshift, using a cosmological model like ΛCDM, we can estimate both the galaxy’s current distance and its present recessional velocity.

So while the redshift comes from ancient light, it still gives us information about the current expansion rate and how fast those galaxies are receding now, even if the light they emit today will never reach us.

What the measured red shift tell us is not at all clear, at least to me. AG

 

> If that's the case, can we conclude that the theory of Inflation must be false, 

That is a strange conclusion to make given the fact that if the theory of Inflation is correct then the rate of expansion of the very early univese was approximately 10^52 (10,000 trillion trillion trillion trillion) times faster than it is today.   

               Not at all strange. If the universe was expanding very slowing immediately after the BB, it would contradict Inflation theory. AG  

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[Brent Meeker]

On 7/16/2025 2:54 PM, Alan Grayson wrote:

On Tuesday, July 15, 2025 at 1:37:35 PM UTC-6 Brent Meeker wrote:

On 7/14/2025 11:13 PM, Alan Grayson wrote:

On Monday, July 14, 2025 at 10:52:44 PM UTC-6 Brent Meeker wrote:

Galaxies formed waaay after the Big Bang and we can't actually observe anything earlier than the recombination around 400,000yr after the BB.

I am aware of that. Nevertheless, the red shift of distant galaxies indicates that they were receding at huge velocities, obviously after they were formed. 

They're receding at huge velocities from us...or are we receding at huge velocities from them.

According to Inflation theory, there was a HUGE, HUGE expansion immediately after the BB, which lasted for a TINY, TINY fraction of the first second. This is generally accepted within the physics community since it answers some pressing issues such as the uniformity of the CMB. AG

I don't know what JKC said about the speed of early expansion, but it seems to be increasing so it will be faster in the future than it was in the past. 

He claimed the early rate of expansion was exceedingly slow, and that the red shift we now observes indicates the current receding velocity. AG 

You do realize don't you that the uniform Hubble expansion means the further away you are from X, the faster you're "receding" from X.  And since it's been a long time since galaxies formed they used to be closer together and hence were not "receding" from one another as fast, even if the expansion of the universe (the Hubble constant) was the same. 

Yes, I am aware of these facts. But my problem is that the light coming from those galaxies is interpreted to mean they are being observed as they existed billions of years ago, whereas the recessional velocity is occurring now and is essentially dependent on geometry; that is, if we imagine a spherically shaped universe and two separated galaxies on its expanding equator, the farther way these galaxies are separated, the faster they are receding from each other. And that's happening now. So how do you reconcile what's happening now, with what the red shift indicates occurred in the distant past? AG

The red shift we observe now...due to our recession?

Brent

[Alan Grayson]

So what's the case? Is the red shift telling us those galaxies were receding rapidly in the past, or due to our recession in the present? AG 

[Alan Grayson]

And note that Clark says the red shift tells us how much the universe has expanded since those early galaxies were formed. Maybe this value is identical to the red shift caused by our recession from those early galaxies? AG

[John Clark]

On Wed, Jul 16, 2025 at 11:52 PM Quentin Anciaux <allc...@gmail.com> wrote:

> Of course, the expansion of the universe was slower following Inflation when the galaxies formed, starting around 380,000 years after the BB, 

 

Galaxies are a lot younger than that. Outside of the Cosmic Microwave Background Radiation, the most distant object astronomers have ever observed is a small but very bright galaxy called MoM‑z14, the James Webb space telescope gave us a picture of that galaxy as it existed  290 million years after the Big Bang. Although if we want a good picture of what that galaxy looked like way back then we have to make some adjustments to the raw data that James Webb gives us. By examining the spectrum we know that most of the light that was emitted by MoM‑z14 was in the ultraviolet, that's not surprising because most of the stars in it were large and very hot, but today when we look at it we mostly see infrared light. Why? Because thanks to the expansion of the universe MoM‑z14 has a HUGE red shift of 14.44.

> but how can the red shift of distant galaxies NOT tell us about their recessional velocity in the distant past, which is what Clark seems to claim? He claims it only tells us how much the universe has expanded since their formation when photon frequency shifted from UV to red.

In cosmology the term "recessional velocity" can be ambiguous because there is a fundamental difference between X traveling through space away from Y and the space between X and Y increasing; one is limited by the speed of causality, a.k.a. the speed of light, but the other is not.  13.5 billion years ago the amount of space between MoM‑z14 and the matter that would one day form the Earth was much less than it is today, and during that light's 13.5 billion year long journey to us space kept expanding, so the wavelength of the light kept getting longer and redder. The amount of space between the Earth and MoM‑z14 keeps getting larger, but that's not because the galaxy was moving away from us through space, but because the very space between it and us kept expanding. 

 > But distant galaxies are receding rapidly NOW? 

"Now" is not a particularly useful word in cosmology. Nobody knows how fast or in what direction MoM‑z14 is moving through space relative to the Earth, and even if we did know I don't think anybody would find that number would be very interesting because whatever it is it's negligible compared to the huge amount of spatial expansion that has occurred since that light was emitted. 

After compensating for the distortion caused by the huge redshift we can form a pretty good picture of what MoM‑z14 looked like 13.5 billion years ago, but we will NEVER get a picture of what it looks like in 2025, not even if we wait 13.5 billion years for it, because long before that it's red shift will become infinite and thus unobservable. There is a limit to how fast two objects can move through space away from each other, but there is no limit on how fast the amount of space between two objects can increase. 

   John K Clark    See what's on my new list at  Extropolis

rfw 

 

[Alan Grayson]

On Thursday, July 17, 2025 at 9:12:14 AM UTC-6 John Clark wrote:

On Wed, Jul 16, 2025 at 11:52 PM Quentin Anciaux <allc...@gmail.com> wrote:

> Of course, the expansion of the universe was slower following Inflation when the galaxies formed, starting around 380,000 years after the BB, 

 

Galaxies are a lot younger than that. 

Younger than 380,000 years??? AG

[Alan Grayson]

This issue continues to confuse me. It seems to me that a red shift will be produced if an object is moving away from us, regardless of the cause of its motion; that is, regardless of whether space is expanding, or the object is moving away from us through space. That's the red shift we observe, and everyone seems to agree that is represents ancient history, what the relative motion was billions of years in the past. So, even though the galaxies were much closer in spatial distance billions of years ago, how can we NOT conclude that those galaxies were receding from each other, AT THAT TIME, AT A HUGE RATE. represented by the measured red shift? TY, AG

[John Clark]

On Thu, Jul 17, 2025 at 9:59 PM Alan Grayson <agrays...@gmail.com> wrote:

> It seems to me that a red shift will be produced if an object is moving away from us, regardless of the cause of its motion; that is, regardless of whether space is expanding, or the object is moving away from us through space. That's the red shift we observe,

Yes.

>and everyone seems to agree that is represents ancient history,

Yes.

 

>what the relative motion was billions of years in the past. 

No, although astronomer sometimes speak imprecisely and people infer that the only way a redshift could be produced is by a thing moving through space away from us. I may have been guilty of such sloppy language myself from time to time.

> So, even though the galaxies were much closer in spatial distance billions of years ago, how can we NOT conclude that those galaxies were receding from each other, AT THAT TIME, AT A HUGE RATE. represented by the measured red shift? TY, AG

A galaxy moving through space away from us is one way to produce a redshift, another way would be for the space between galaxys to be expanding, we can determine which one is actually causing the redshift through observation. Except for the Andromeda and Triangulum galaxies and about a dozen dwarf galaxies in our local group, every galaxy in the universe is displaying a redshift to us, and the more distant it is the larger it's redshift. If that redshift is caused by them moving through space away from us then the Earth is it a very special position, the center of the universe. However the idea that the universe contains anything as mundane as a center is problematic, and the Earth just happening to occupy that center is even more so.

But if the redshift is caused buy the expansion of space itself then every observer in every galaxy would see the same thing that we do, except for a few very nearby ones, every galaxy in the universe would be displaying a redshift to them, and the more distant it is the larger it's redshift.

 John K Clark    See what's on my new list at  Extropolis

dq?

[Brent Meeker]

We don't have any direct measure of the red shift then, only the redshift now.  And it's the redshift between us and various galaxies at different distances.  Beyond our local group the red shift due proper motion is trivial.  It's all due to the overall expansion of the universe and the gravitational potential.  So it's a matter of fitting all the data from galaxies at all different distances to a model, like this:



https://www.britannica.com/science/cosmology-astronomy/Superunification-and-the-Planck-era

Note that this does not include inflation which, if it happened, preceded this expansion which is just the process modeled by general relativity applied to a homogeneous and isotropic universe.

Brent

[Brent Meeker]

On 7/18/2025 4:10 AM, John Clark wrote:

On Thu, Jul 17, 2025 at 9:59 PM Alan Grayson <agrays...@gmail.com> wrote:

> It seems to me that a red shift will be produced if an object is moving away from us, regardless of the cause of its motion; that is, regardless of whether space is expanding, or the object is moving away from us through space. That's the red shift we observe,

Yes.

>and everyone seems to agree that is represents ancient history,

Yes.

 

>what the relative motion was billions of years in the past. 

No, although astronomer sometimes speak imprecisely and people infer that the only way a redshift could be produced is by a thing moving through space away from us. I may have been guilty of such sloppy language myself from time to time.

> So, even though the galaxies were much closer in spatial distance billions of years ago, how can we NOT conclude that those galaxies were receding from each other, AT THAT TIME, AT A HUGE RATE. represented by the measured red shift? TY, AG

A galaxy moving through space away from us is one way to produce a redshift, another way would be for the space between galaxys to be expanding, we can determine which one is actually causing the redshift through observation. Except for the Andromeda and Triangulum galaxies and about a dozen dwarf galaxies in our local group, every galaxy in the universe is displaying a redshift to us, and the more distant it is the larger it's redshift. If that redshift is caused by them moving through space away from us then the Earth is it a very special position, the center of the universe. However the idea that the universe contains anything as mundane as a center is problematic, and the Earth just happening to occupy that center is even more so.

But if the redshift is caused buy the expansion of space itself then every observer in every galaxy would see the same thing that we do, except for a few very nearby ones, every galaxy in the universe would be displaying a redshift to them, and the more distant it is the larger it's redshift.

Good, except there is also a small component due to the higher mass density in the universe in the distant past which also adds to the redshift relative to us.  And while "the more distant it is the larger it's redshift" is true, the relation is not linear as encoded in a Hubble constant.  That's where talk of accelerated expansion comes from.

Brent

[Alan Grayson]

Generally speaking I still don't get it. What I do get is that since the Earth isn't the center of the universe, the red shift observed cannot be due to relative motion in space, but to the expansion of the universe. HOWEVER, Clark (and you?) agrees that the observations correspond to behavior in the distant past, and the further back in time we go via Hubble, the red shift increases, implying increasing recessional velocity. If that's the case, why does Clark (and you?) claim that in the very early universe, the galaxies were receding from each other slowly, presumably much slowly than today? AG 

[Brent Meeker]

On 7/18/2025 5:18 PM, Alan Grayson wrote:

On Friday, July 18, 2025 at 5:04:35 PM UTC-6 Brent Meeker wrote:

On 7/18/2025 4:10 AM, John Clark wrote:

On Thu, Jul 17, 2025 at 9:59 PM Alan Grayson <agrays...@gmail.com> wrote:

> It seems to me that a red shift will be produced if an object is moving away from us, regardless of the cause of its motion; that is, regardless of whether space is expanding, or the object is moving away from us through space. That's the red shift we observe,

Yes.

>and everyone seems to agree that is represents ancient history,

Yes.

 

>what the relative motion was billions of years in the past. 

No, although astronomer sometimes speak imprecisely and people infer that the only way a redshift could be produced is by a thing moving through space away from us. I may have been guilty of such sloppy language myself from time to time.

> So, even though the galaxies were much closer in spatial distance billions of years ago, how can we NOT conclude that those galaxies were receding from each other, AT THAT TIME, AT A HUGE RATE. represented by the measured red shift? TY, AG

A galaxy moving through space away from us is one way to produce a redshift, another way would be for the space between galaxys to be expanding, we can determine which one is actually causing the redshift through observation. Except for the Andromeda and Triangulum galaxies and about a dozen dwarf galaxies in our local group, every galaxy in the universe is displaying a redshift to us, and the more distant it is the larger it's redshift. If that redshift is caused by them moving through space away from us then the Earth is it a very special position, the center of the universe. However the idea that the universe contains anything as mundane as a center is problematic, and the Earth just happening to occupy that center is even more so.

But if the redshift is caused buy the expansion of space itself then every observer in every galaxy would see the same thing that we do, except for a few very nearby ones, every galaxy in the universe would be displaying a redshift to them, and the more distant it is the larger it's redshift.

Good, except there is also a small component due to the higher mass density in the universe in the distant past which also adds to the redshift relative to us.  And while "the more distant it is the larger it's redshift" is true, the relation is not linear as encoded in a Hubble constant.  That's where talk of accelerated expansion comes from.

Brent

Generally speaking I still don't get it. What I do get is that since the Earth isn't the center of the universe, the red shift observed cannot be due to relative motion in space, but to the expansion of the universe. 

It's all relative motion in space.  But only the part due to the expansion of the universe is significant; so forget the local proper motion.

HOWEVER, Clark (and you?) agrees that the observations correspond to behavior in the distant past, 

I don't know what that means.  Galaxies are observed at all different distances and corresponding different times in the past.  Then it is a curve fitting problem to say what universe model best fits the data.  

and the further back in time we go via Hubble, the red shift increases, implying increasing recessional velocity. 

Yes, things further away have a higher redshift.  We have a higher recessional velocity relative to them.

If that's the case, why does Clark (and you?) claim that in the very early universe, the galaxies were receding from each other slowly, presumably much slowly than today? AG 

Look at the curves I posted.  Most of them, but not all, show a lower Hubble parameter, less slope, earlier.

Brent

[Alan Grayson]

On Friday, July 18, 2025 at 7:27:31 PM UTC-6 Brent Meeker wrote:

On 7/18/2025 5:18 PM, Alan Grayson wrote:

On Friday, July 18, 2025 at 5:04:35 PM UTC-6 Brent Meeker wrote:

On 7/18/2025 4:10 AM, John Clark wrote:

On Thu, Jul 17, 2025 at 9:59 PM Alan Grayson <agrays...@gmail.com> wrote:

> It seems to me that a red shift will be produced if an object is moving away from us, regardless of the cause of its motion; that is, regardless of whether space is expanding, or the object is moving away from us through space. That's the red shift we observe,

Yes.

>and everyone seems to agree that is represents ancient history,

Yes.

 

>what the relative motion was billions of years in the past. 

No, although astronomer sometimes speak imprecisely and people infer that the only way a redshift could be produced is by a thing moving through space away from us. I may have been guilty of such sloppy language myself from time to time.

> So, even though the galaxies were much closer in spatial distance billions of years ago, how can we NOT conclude that those galaxies were receding from each other, AT THAT TIME, AT A HUGE RATE. represented by the measured red shift? TY, AG

A galaxy moving through space away from us is one way to produce a redshift, another way would be for the space between galaxys to be expanding, we can determine which one is actually causing the redshift through observation. Except for the Andromeda and Triangulum galaxies and about a dozen dwarf galaxies in our local group, every galaxy in the universe is displaying a redshift to us, and the more distant it is the larger it's redshift. If that redshift is caused by them moving through space away from us then the Earth is it a very special position, the center of the universe. However the idea that the universe contains anything as mundane as a center is problematic, and the Earth just happening to occupy that center is even more so.

But if the redshift is caused buy the expansion of space itself then every observer in every galaxy would see the same thing that we do, except for a few very nearby ones, every galaxy in the universe would be displaying a redshift to them, and the more distant it is the larger it's redshift.

Good, except there is also a small component due to the higher mass density in the universe in the distant past which also adds to the redshift relative to us.  And while "the more distant it is the larger it's redshift" is true, the relation is not linear as encoded in a Hubble constant.  That's where talk of accelerated expansion comes from.

Brent

Generally speaking I still don't get it. What I do get is that since the Earth isn't the center of the universe, the red shift observed cannot be due to relative motion in space, but to the expansion of the universe. 

It's all relative motion in space.  But only the part due to the expansion of the universe is significant; so forget the local proper motion.

HOWEVER, Clark (and you?) agrees that the observations correspond to behavior in the distant past, 

I don't know what that means.  Galaxies are observed at all different distances and corresponding different times in the past.  Then it is a curve fitting problem to say what universe model best fits the data.  

You don't know what I mean? It's simple; at any distance for a particular galaxy, we're seeing it in the past, depending on how far away it is. And the farther away it is, the greater is its red shift and recessional velocity. So the recessional velocity seems to be DECREASING with time as the universe expands. But if this is true, how could galaxies at the furthest distance from us, be separating from us and each other at a slow rate as Clark (and you?) claims? Maybe much slower than during Inflation, but still presumably very rapid. AG

[Brent Meeker]

On 7/18/2025 6:49 PM, Alan Grayson wrote:

And the farther away it is, the greater is its red shift and recessional velocity. So the recessional velocity seems to be DECREASING with time as the universe expands. 

The second does not follow from the first.  Further away means later in time.  Further away is receding faster.

Brent

[John Clark]

On Fri, Jul 18, 2025 at 8:18 PM Alan Grayson <agrays...@gmail.com> wrote:

 > the red shift increases, implying increasing recessional velocity.

The above statement is the source of your confusion. You cannot conclude that if there is a redshift then there must be a recessional velocity because the movement of something through space is just one way to produce a redshift, there are two other ways that it can happen:

1) The space between the Earth and very distant objects could be expanding. 

2) The light may have to fight its way out of a strong gravitational field. But we know that can't be a major factor in forming the redshift we see from very distant galaxies because, from gravitational lensing, we can determine that the gravitational field around those galaxies is not nearly strong enough to produce such a massive redshift.    

 John K Clark    See what's on my new list at  Extropolis

{(%

[Alan Grayson]

Let me rephase that; first, consider the model of the universe as an expanding sphere and two separated galaxies on that sphere, say on the equator. As we discussed, it's an effect of geometry that the rate of the separation distance increases depending on the initial separation distance, and the red shift increases as well as the separation velocity. That's as time moves forward. Now we get the same result when we consider time moving backward, as we look backward in time and see the red shift and recessional velocity increasing. There's my dilemma. Whether we go backward or forward in time, two separated galaxies exhibit increasing red shift and increasing recessional velocity. AG

[Alan Grayson]

On Saturday, July 19, 2025 at 5:17:32 AM UTC-6 John Clark wrote:

On Fri, Jul 18, 2025 at 8:18 PM Alan Grayson <agrays...@gmail.com> wrote:

 > the red shift increases, implying increasing recessional velocity.

The above statement is the source of your confusion. You cannot conclude that if there is a redshift then there must be a recessional velocity because the movement of something through space is just one way to produce a redshift, there are two other ways that it can happen:

You previously agreed that although there could be more than one cause of red shift, with one exception it always indicates recessional velocity from the pov of the observer measuring that red shift. The exception is gravitational red shift. AG 

[Brent Meeker]

On 7/19/2025 10:54 AM, Alan Grayson wrote:

On Friday, July 18, 2025 at 11:34:17 PM UTC-6 Brent Meeker wrote:

On 7/18/2025 6:49 PM, Alan Grayson wrote:

And the farther away it is, the greater is its red shift and recessional velocity. So the recessional velocity seems to be DECREASING with time as the universe expands. 

The second does not follow from the first.  Further away means later in time.  Further away is receding faster.

Brent

Let me rephase that; first, consider the model of the universe as an expanding sphere and two separated galaxies on that sphere, say on the equator. As we discussed, it's an effect of geometry that the rate of the separation distance increases depending on the initial separation distance, and the red shift increases as well as the separation velocity. 

Why do you write "as well as"?  The red shift is due to the separation velocity.

That's as time moves forward. Now we get the same result when we consider time moving backward, as we look backward in time and see the red shift and recessional velocity increasing. 

First you write "consider time moving backward" and then you write "as we look backward"??   Are you considering time reversed motion; bodies moving closer together?  Or are you just thinking of how things must have been ten or so billion years ago?  Or are you saying you're going to look at some distant galaxies, which are implicitly far back in time from the "now" defined by distance from the CMB?  What are you measuring the recessional velocity from?  From some specific galaxy?  Or from galaxies at some specific distance?  If you mean a specific galaxy then in the past we were closer to it and therefore our recession from it was slower.  If you mean galaxies at a specific distance then the Hubble parameter being constant means that recession velocity was the same in the past.

Try thinking in terms of the Hubble parameter as constant.  That means space has been expanding by a constant multiplier, e>1, per unit time.  So our recessional velocity relative to galaxies at a given distance D, is and always has been De.  Once you've got that straight you can consider models in with e changes with time from the Big Bang, which is modeled by all those nice colored curves I posted.

There's my dilemma. Whether we go backward or forward in time, two separated galaxies exhibit increasing red shift and increasing recessional velocity. AG

No, e is a constant.  So if you consider two specific galaxies their separation in the past was less and a smaller D means a lesser recessional velocity De.

Brent

[Brent Meeker]

On 7/19/2025 11:07 AM, Alan Grayson wrote:

On Saturday, July 19, 2025 at 5:17:32 AM UTC-6 John Clark wrote:

On Fri, Jul 18, 2025 at 8:18 PM Alan Grayson <agrays...@gmail.com> wrote:

 > the red shift increases, implying increasing recessional velocity.

The above statement is the source of your confusion. You cannot conclude that if there is a redshift then there must be a recessional velocity because the movement of something through space is just one way to produce a redshift, there are two other ways that it can happen:

You previously agreed that although there could be more than one cause of red shift, with one exception it always indicates recessional velocity from the pov of the observer measuring that red shift. The exception is gravitational red shift. AG 

Forget about the gravitational red shift.  It is relatively small.  Similarly, forget about "something moving thru space".  That is also negligible for distant galaxies.  Just concentrate on understanding the "expansion of space", the Hubble expansion part, first.

Brent

1) The space between the Earth and very distant objects could be expanding. 

2) The light may have to fight its way out of a strong gravitational field. But we know that can't be a major factor in forming the redshift we see from very distant galaxies because, from gravitational lensing, we can determine that the gravitational field around those galaxies is not nearly strong enough to produce such a massive redshift.    

 John K Clark    See what's on my new list at  Extropolis

{(%

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[Alan Grayson]

On Saturday, July 19, 2025 at 6:48:18 PM UTC-6 Brent Meeker wrote:

On 7/19/2025 10:54 AM, Alan Grayson wrote:

On Friday, July 18, 2025 at 11:34:17 PM UTC-6 Brent Meeker wrote:

On 7/18/2025 6:49 PM, Alan Grayson wrote:

And the farther away it is, the greater is its red shift and recessional velocity. So the recessional velocity seems to be DECREASING with time as the universe expands. 

The second does not follow from the first.  Further away means later in time.  Further away is receding faster.

Brent

Let me rephase that; first, consider the model of the universe as an expanding sphere and two separated galaxies on that sphere, say on the equator. As we discussed, it's an effect of geometry that the rate of the separation distance increases depending on the initial separation distance, and the red shift increases as well as the separation velocity. 

Why do you write "as well as"?  The red shift is due to the separation velocity.

OK, no problem. AG

That's as time moves forward. Now we get the same result when we consider time moving backward, as we look backward in time and see the red shift and recessional velocity increasing. 

First you write "consider time moving backward" and then you write "as we look backward"??   Are you considering time reversed motion; bodies moving closer together?  Or are you just thinking of how things must have been ten or so billion years ago?  Or are you saying you're going to look at some distant galaxies, which are implicitly far back in time from the "now" defined by distance from the CMB?  What are you measuring the recessional velocity from?  From some specific galaxy?  Or from galaxies at some specific distance?  If you mean a specific galaxy then in the past we were closer to it and therefore our recession from it was slower.  If you mean galaxies at a specific distance then the Hubble parameter being constant means that recession velocity was the same in the past.

I'm considering galaxies in varying distances from our galaxy, so I'm looking at recessional velocities in the past, and they are all increasing.  So, even though a now distant galaxy was close to the point in spacetime which was where our galaxy came into existence, wasn't it still receding rapidly from that location? How then can anyone conclude that the separation velocity was small? AG

[Brent Meeker]

On 7/19/2025 7:36 PM, Alan Grayson wrote:

On Saturday, July 19, 2025 at 6:48:18 PM UTC-6 Brent Meeker wrote:

On 7/19/2025 10:54 AM, Alan Grayson wrote:

On Friday, July 18, 2025 at 11:34:17 PM UTC-6 Brent Meeker wrote:

On 7/18/2025 6:49 PM, Alan Grayson wrote:

And the farther away it is, the greater is its red shift and recessional velocity. So the recessional velocity seems to be DECREASING with time as the universe expands. 

The second does not follow from the first.  Further away means later in time.  Further away is receding faster.

Brent

Let me rephase that; first, consider the model of the universe as an expanding sphere and two separated galaxies on that sphere, say on the equator. As we discussed, it's an effect of geometry that the rate of the separation distance increases depending on the initial separation distance, and the red shift increases as well as the separation velocity. 

Why do you write "as well as"?  The red shift is due to the separation velocity.

OK, no problem. AG

That's as time moves forward. Now we get the same result when we consider time moving backward, as we look backward in time and see the red shift and recessional velocity increasing. 

First you write "consider time moving backward" and then you write "as we look backward"??   Are you considering time reversed motion; bodies moving closer together?  Or are you just thinking of how things must have been ten or so billion years ago?  Or are you saying you're going to look at some distant galaxies, which are implicitly far back in time from the "now" defined by distance from the CMB?  What are you measuring the recessional velocity from?  From some specific galaxy?  Or from galaxies at some specific distance?  If you mean a specific galaxy then in the past we were closer to it and therefore our recession from it was slower.  If you mean galaxies at a specific distance then the Hubble parameter being constant means that recession velocity was the same in the past.

I'm considering galaxies in varying distances from our galaxy, so I'm looking at recessional velocities in the past, and they are all increasing.  

So you're considering recessional velocities from specific galaxies, all of which are increasing and that implies that in the past all those velocities were smaller.

So, even though a now distant galaxy was close to the point in spacetime which was where our galaxy came into existence, wasn't it still receding rapidly from that location? 

No.  Recession velocity is De.  So if our galaxy came into existence near another galaxy, D was small and our recession velocity from that galaxy was small.

Brent

How then can anyone conclude that the separation velocity was small? AG

Try thinking in terms of the Hubble parameter as constant.  That means space has been expanding by a constant multiplier, e>1, per unit time.  So our recessional velocity relative to galaxies at a given distance D, is and always has been De.  Once you've got that straight you can consider models in with e changes with time from the Big Bang, which is modeled by all those nice colored curves I posted.

There's my dilemma. Whether we go backward or forward in time, two separated galaxies exhibit increasing red shift and increasing recessional velocity. AG

No, e is a constant.  So if you consider two specific galaxies their separation in the past was less and a smaller D means a lesser recessional velocity De.

Brent

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[Liz R]

I suspect you're conflating two vastly different things? Light from distant galaxies - what's used to measure the Hubble constant - was emitted WAY after the hypothetical inflationary era. The Hubble expansion only refers to the increasing separation between galaxies/clusters of galaxies/similar observable objects/groups. It isn't possible to make deductions about inflation (except indirectly, e.g. from the observed homogeneity of matter in the universe) from observable objects, which formed a lot later. The earliest directly observable thing in the universe (at present) is the microwave background. It's possible neutrinos or gravitational waves will let us observe earlier eventa, but none of these appraoch the inflationary era, which predates the quark-gluon plasma that became nuclei etc.

On Tuesday, 15 July 2025 at 14:30:28 UTC+12 Alan Grayson wrote:

Given the fact that light from very distant galaxies is hugely red-shifted, and the general belief that light we're observing today from those distant galaxies, was emitted when the universe was very young, one would conclude that the rate of expansion at that time was huge. But Clark disputes this conclusion. He claims the opposite; that the rate of expansion in the very early universe was exceedingly SLOW. If that's the case, can we conclude that the theory of Inflation must be false, insofar as it alleges a huge initial expansion rate to account for the observed uniformity of the current universe? Moreover, Hubble's law confirms that as we go back in time, the universe was expanding faster than it is today, again apparently confirming the Inflation theory of a very high initial rate of expansion (ignoring recent findings the the rate of expansion is iagain ncreasing). AG

[John Clark]

On Sun, Jul 20, 2025 at 1:11 AM Liz R <liz...@gmail.com> wrote:

> The earliest directly observable thing in the universe (at present) is the microwave background. It's possible neutrinos or gravitational waves will let us observe earlier eventa, but none of these appraoch the inflationary era, which predates the quark-gluon plasma that became nuclei etc.

If inflation existed then we should be able to detect the primordial gravitational waves it produced, although that won't be easy. In 2014 a group of astronomers thought they had done that, they thought they had observed polarization pattering in the Cosmic Microwave Background Radiation (CMBR) caused by those primordial gravitational waves, but it turned out to be caused by the magnetic field of our own galaxy. 

However the technique itself remains sound because our galaxy's magnetic field affects the polarization of different frequencies of the CMBR differently, so in principle we can cancel out the noise caused by magnetic fields and see the effect caused by primordial gravitational waves, assuming they actually exist. But to do that our measurements need to be incredibly precise.

Our best hope for finding those primordial gravitational waves caused by inflation was the CMB-S4 microwave telescope being built at the south pole, if it had been completed then by 2030 we would know if such waves actually exist. However about two weeks ago on July 9, in an attempt to make America great again, Trump canceled CMB-S4:

US. abandons hunt for signal of cosmic inflation

Trump killed CMB-S4 despite US scientists wanting it very badly, or perhaps because they wanted it, Trump doesn't like scientists very much. A 2021 survey of particle physicists said that out of all the proposed future projects CMB-S4 should be first one on the priority list. Astronomers said it should be #2 after a successor for the aging Hubble space telescope, something with a larger mirror and works at optical and near ultraviolet frequencies. Hubble was only designed to work for 15 years, but it's already been operating for nearly 29. Nevertheless I wouldn't be a bit surprised if Trump cancels Hubble's successor too.

 John K Clark    See what's on my new list at  Extropolis

rbr

[Alan Grayson]

On Saturday, July 19, 2025 at 11:11:27 PM UTC-6 Liz R wrote:

I suspect you're conflating two vastly different things? Light from distant galaxies - what's used to measure the Hubble constant - was emitted WAY after the hypothetical inflationary era.

No; I'm definitely not conflating the hypothetical inflationary period, which is conjectured to have occurred (and concluded) during the first second after the BB, whereas galaxy formation occurred after 380,000, when the CMB manifested.  AG

 

The Hubble expansion only refers to the increasing separation between galaxies/clusters of galaxies/similar observable objects/groups. It isn't possible to make deductions about inflation (except indirectly, e.g. from the observed homogeneity of matter in the universe) from observable objects, which formed a lot later.

 

I made no deductions about inflation. Rather, I am confused why Clark claims the red shift observed today from ancient galaxies, is consistent with SLOW cosmic expansion at that time, when it's generally accepted that the red shift we measure today left those galaxies well in the past, and AFAIK, has always been interpreted as due to expansion of the cosmos. It's obvious that in ancient times galaxies were much more closely separated than presently, but Clark ALSO claims the rate of expansion was small at that time. The red shift of those galaxies seems to indicate otherwise, although this high rate of expansion is small compared to inflation, which was (if it occurred) much faster than light speed. AG

[John Clark]

On Sun, Jul 20, 2025 at 2:38 PM Alan Grayson <agrays...@gmail.com> wrote:

 

> I made no deductions about inflation.

On July 14 you said "the theory of Inflation must be false, insofar as it alleges a huge initial expansion rate to account for the observed uniformity of the current universe", but perhaps you've changed your mind, and there is no disgrace in doing that.

 

> it's generally accepted that the red shift we measure today left those galaxies well in the past, and AFAIK, has always been interpreted as due to expansion of the cosmos.

Yes  light left those galaxies long long ago, and during its multi billion year journey space has been expanding, and that spatial expansion produces a redshift. 

< It's obvious that in ancient times galaxies were much more closely separated than presently,

Yes

 

but Clark ALSO claims the rate of expansion was small at that time.

Yes, back then the average distance between galaxies was less than it is now, and the rate at which that distance was increasing was also smaller. Well... if I'm being pedantic it's a little more complicated than that. In the late 1990s it was discovered that during the first 9 billion years of the universe's existence the rate of expansion of the universe was indeed slowing down just as you'd expect because gravity is attractive but then, about 5 billion years ago, there was a cosmic "jerk" (the rate of increase of acceleration) and the rate at which the universe was expanding started to increase. 

This can be explained if a property of empty space is that it has a negative pressure which according to Einstein causes space to expand, so the more space there is the larger the effect; but matter produces a positive pressure which causes the expansion to slow down, but the more space there is the more diluted matter becomes and the weaker this effect. As the universe expands dark energy, which wants the universe to expand faster, does not become diluted. But matter, which wants the universe to contract, does become diluted.  And that produces a jerk.   

 

>The red shift of those galaxies seems to indicate otherwise,

From that I must conclude that you still don't understand that there is a difference between a galaxy moving away from us through space and the space between us and the galaxy expanding, and you still don't understand that there's more than one way to create a redshift.   

 John K Clark    See what's on my new list at  Extropolis

noo

[Alan Grayson]

On Sunday, July 20, 2025 at 1:42:22 PM UTC-6 John Clark wrote:

On Sun, Jul 20, 2025 at 2:38 PM Alan Grayson <agrays...@gmail.com> wrote:

 

> I made no deductions about inflation.

On July 14 you said "the theory of Inflation must be false, insofar as it alleges a huge initial expansion rate to account for the observed uniformity of the current universe", but perhaps you've changed your mind, and there is no disgrace in doing that.

That was either my typo or your misquote, since the rationale for inflation is pretty strong IMO. I'll check on that later today, after my laundry. I forget, but there's another important prediction of inflation, which is verified in the CMB. Do you recall what it is? AG 

 

> it's generally accepted that the red shift we measure today left those galaxies well in the past, and AFAIK, has always been interpreted as due to expansion of the cosmos.

Yes  light left those galaxies long long ago, and during its multi billion year journey space has been expanding, and that spatial expansion produces a redshift. 

< It's obvious that in ancient times galaxies were much more closely separated than presently,

Yes

 

but Clark ALSO claims the rate of expansion was small at that time.

Yes, back then the average distance between galaxies was less than it is now, and the rate at which that distance was increasing was also smaller.

I really don't see how the rate of expansion can be smaller today, since the measured value in ancient times is much larger than it is today, ignoring the new data from the late 1990's. AG

 

Well... if I'm being pedantic it's a little more complicated than that. In the late 1990s it was discovered that during the first 9 billion years of the universe's existence the rate of expansion of the universe was indeed slowing down just as you'd expect because gravity is attractive but then, about 5 billion years ago, there was a cosmic "jerk" (the rate of increase of acceleration) and the rate at which the universe was expanding started to increase. 

This can be explained if a property of empty space is that it has a negative pressure which according to Einstein causes space to expand,

Can you say more about negative pressure and its cause? AG

 

so the more space there is the larger the effect; but matter produces a positive pressure which causes the expansion to slow down, but the more space there is the more diluted matter becomes and the weaker this effect. As the universe expands dark energy, which wants the universe to expand faster, does not become diluted. But matter, which wants the universe to contract, does become diluted.  And that produces a jerk.   

 

>The red shift of those galaxies seems to indicate otherwise,

From that I must conclude that you still don't understand that there is a difference between a galaxy moving away from us through space and the space between us and the galaxy expanding, and you still don't understand that there's more than one way to create a redshift. 

I clearly understand both issues, and have no problem with either. As Brent wrote, and we can agree, the red shift due to motion through space can be ignored. If the red shift observed came from the expansion of the cosmos, then what we observe with respect to the red shift was NOT caused in the ancient past, and this must be the basis for your claim, that the cosmos was not expanding fast at that time. If so, why do you assert that what we observe today, including the red shift, originated in the ancient past? I think my confusion is the generally held belief that the light we observe from ancient galaxies, originated in the ancient past, but the observed red shift is apparently an unstated exception. So, when it's claimed those ancient galaxies are receding rapidly, they're NOT referring to what was occurring ancient times, but NOW. AG

[Alan Grayson]

On Sunday, July 20, 2025 at 1:42:22 PM UTC-6 John Clark wrote:

On Sun, Jul 20, 2025 at 2:38 PM Alan Grayson <agrays...@gmail.com> wrote:

 

> I made no deductions about inflation.

On July 14 you said "the theory of Inflation must be false, insofar as it alleges a huge initial expansion rate to account for the observed uniformity of the current universe", but perhaps you've changed your mind, and there is no disgrace in doing that.

I just checked. The problem with my claim in that post was that I didn't define "the very early universe". If you meant the first second (which you did not), then your claim that the rate of expansion was slow AT THE TIME, it would have been falsified Inflation theory. But that's not what you meant. You were referring to the time after the formation of the galaxies, well AFTER the formation of the CMB, 380,000 years after the BB. AG 

[Alan Grayson]

On Sunday, July 20, 2025 at 3:12:25 PM UTC-6 Alan Grayson wrote:

On Sunday, July 20, 2025 at 1:42:22 PM UTC-6 John Clark wrote:

On Sun, Jul 20, 2025 at 2:38 PM Alan Grayson <agrays...@gmail.com> wrote:

 

> I made no deductions about inflation.

On July 14 you said "the theory of Inflation must be false, insofar as it alleges a huge initial expansion rate to account for the observed uniformity of the current universe", but perhaps you've changed your mind, and there is no disgrace in doing that.

I just checked. The problem with my claim in that post was that I didn't define "the very early universe". If you meant the first second (which you did not), then your claim that the rate of expansion was slow AT THAT TIME, would have falsified Inflation theory. But that's not what you meant. You were referring to the time after the formation of the galaxies, well AFTER the formation of the CMB, 380,000 years after the BB. AG 

[John Clark]

On Sun, Jul 20, 2025 at 4:59 PM Alan Grayson <agrays...@gmail.com> wrote:

 > I forget, but there's another important prediction of inflation, which is verified in the CMB. Do you recall what it is? AG 

Inflation correctly predicted that the intensity of the CMB should be almost constant from one place to another, but not perfectly constant, it should change in about one part in 100,000. It's not perfect because of Heisenberg's Uncertainty Principle, tiny changes in the very very early universe were enormously magnified by inflation from the sub microscopic level to cosmic scale. Inflation also explains why at the largest scale space is flat, inflation ironed out any wrinkles that were produced before the era of inflation. It even explains why we have never seen a Magnetic Monopole even though many particle physics theories predicted they should be stable and have been produced in huge numbers back when the entire universe was super hot, inflation diluted their concentration so much that now there may only be one Magnetic Monopole in the entire visible universe, and perhaps none at all.

>>back then the average distance between galaxies was less than it is now, and the rate at which that distance was increasing was also smaller.

> I really don't see how the rate of expansion can be smaller today,

The RATE of expansion of the universe is NOT smaller today, except for the era of inflation which ended about 10^-33 seconds after the start of the Big Bang, it's larger today than it has ever been. The average distance between galaxies was less 5 billion years ago than it is today, and the RATE of increase of those galactic distances was also less 5 billion years ago than it is today. I don't understand why you think those two statements are contradictory. 

> since the measured value in ancient times is much larger than it is today, 

We observe light from a distant galaxy today but it took that light 5 billion years to reach our telescope, and during that long journey the expansion of space has distorted that light. If we want to know what things were like back then we have to understand that distortion and take it into account.    

 

>> if I'm being pedantic it's a little more complicated than that. In the late 1990s it was discovered that during the first 9 billion years of the universe's existence the rate of expansion of the universe was indeed slowing down just as you'd expect because gravity is attractive but then, about 5 billion years ago, there was a cosmic "jerk" (the rate of increase of acceleration) and the rate at which the universe was expanding started to increase. 

This can be explained if a property of empty space is that it has a negative pressure which according to Einstein causes space to expand,

> Can you say more about negative pressure and its cause? AG

The gravitational potential energy of a sphere of particles of matter like sand is always negative, this is true in Newtonian Physics and remains true in General Relativity, so the gravitational potential energy of a sphere of particles of mass-energy M and radius R is PE= (-G*M^2)/R  where G is the gravitational constant. It’s important to note that this is negative energy, so the larger R gets the closer the potential energy gets to zero, and if it was at infinity it would be precisely zero. 

If the sphere expands and is made of sand, which is normal matter, then M stays the same but R increases, so the gravitational potential energy becomes less negative and more positive, and that means it's uphill; It would take an external expenditure of work to do that, so if you let the sphere go to rest it would fall inward as you'd expect.

However if the sphere is primarily made of empty space and IF empty space contains energy, which Einstein's General Theory Of Relativity allows for but does not insist on, then things would be different because unlike an expanding sphere made of sand, the density of mass/energy inside an expanding sphere of empty space would NOT decrease with expansion. So if the sphere expands then, although R increases, M^2 increases even more, so the overall gravitational potential energy becomes larger, and thus more negative. Thus if the vacuum contains negative energy then as the sphere increases in size it becomes more negative and that means expansion is downhill, and so no work is used but instead work is produced. So in any universe in which vacuum energy dominates that universe will expand, it will fall outward and accelerate. 

Most physicists (but not all, see the next paragraph) think vacuum energy is what makes our universe accelerate. You might ask if the sphere gets larger what makes it get larger, where did that mass/energy come from? The answer is: It comes from the gravitational energy released as the sphere of vacuum energy falls outward. So at any point in this process if you add up all the positive kinetic energy and energy locked up in matter (remember E=MC^2) of the universe and all the negative potential gravitational energy of the universe you always get precisely zero.

As I said a minority of physicists reject the idea that Dark Energy is an intrinsic part of space itself and think it's really caused by a scalar (something that has a magnitude but no direction) quantum field that fills the entire universe, and they call that field "Quintessence". If Dark Energy is a field then that opens up the possibility of it changing with time. 

In just the last few months astronomers have found hints that Dark Energy might be getting weaker. The evidence is good enough to be interesting but not good enough to claim a discovery; IF it turns out to be true then Dark Energy cannot be an intrinsic part of space and some form of Quintessence must be true. But that's a big "IF".  

 John K Clark    See what's on my new list at  Extropolis 

tbi

[Brent Meeker]

On 7/21/2025 5:40 AM, John Clark wrote:

On Sun, Jul 20, 2025 at 4:59 PM Alan Grayson <agrays...@gmail.com> wrote:

 > I forget, but there's another important prediction of inflation, which is verified in the CMB. Do you recall what it is? AG 

Inflation correctly predicted that the intensity of the CMB should be almost constant from one place to another, but not perfectly constant, it should change in about one part in 100,000. It's not perfect because of Heisenberg's Uncertainty Principle, tiny changes in the very very early universe were enormously magnified by inflation from the sub microscopic level to cosmic scale. Inflation also explains why at the largest scale space is flat, inflation ironed out any wrinkles that were produced before the era of inflation. It even explains why we have never seen a Magnetic Monopole even though many particle physics theories predicted they should be stable and have been produced in huge numbers back when the entire universe was super hot, inflation diluted their concentration so much that now there may only be one Magnetic Monopole in the entire visible universe, and perhaps none at all.

>>back then the average distance between galaxies was less than it is now, and the rate at which that distance was increasing was also smaller.

> I really don't see how the rate of expansion can be smaller today,

The RATE of expansion of the universe is NOT smaller today, except for the era of inflation which ended about 10^-33 seconds after the start of the Big Bang, it's larger today than it has ever been. The average distance between galaxies was less 5 billion years ago than it is today, and the RATE of increase of those galactic distances was also less 5 billion years ago than it is today. I don't understand why you think those two statements are contradictory. 

I think there may be an ambiguity in the use of "rate of expansion".  There is an observed rate of recession of distant galaxies measured by redshift and used to calculate a velocity between us an some galaxy.  Then there is the Hubble constant which is a percentage rate of expansion which is just an inverse time.

> since the measured value in ancient times is much larger than it is today, 

We observe light from a distant galaxy today but it took that light 5 billion years to reach our telescope, and during that long journey the expansion of space has distorted that light. If we want to know what things were like back then we have to understand that distortion and take it into account.    

 

>> if I'm being pedantic it's a little more complicated than that. In the late 1990s it was discovered that during the first 9 billion years of the universe's existence the rate of expansion of the universe was indeed slowing down just as you'd expect because gravity is attractive but then, about 5 billion years ago, there was a cosmic "jerk" (the rate of increase of acceleration) and the rate at which the universe was expanding started to increase. 

This can be explained if a property of empty space is that it has a negative pressure which according to Einstein causes space to expand,

> Can you say more about negative pressure and its cause? AG

The gravitational potential energy of a sphere of particles of matter like sand is always negative, this is true in Newtonian Physics and remains true in General Relativity, so the gravitational potential energy of a sphere of particles of mass-energy M and radius R is PE= (-G*M^2)/R  where G is the gravitational constant. It’s important to note that this is negative energy, so the larger R gets the closer the potential energy gets to zero, and if it was at infinity it would be precisely zero. 

If the sphere expands and is made of sand, which is normal matter, then M stays the same but R increases, so the gravitational potential energy becomes less negative and more positive, and that means it's uphill; It would take an external expenditure of work to do that, so if you let the sphere go to rest it would fall inward as you'd expect.

But if the total energy, gravitational potential plus sand kinetic, is zero then the sphere will expand forever but with a rate asymptotically approaching zero.

Brent

However if the sphere is primarily made of empty space and IF empty space contains energy, which Einstein's General Theory Of Relativity allows for but does not insist on, then things would be different because unlike an expanding sphere made of sand, the density of mass/energy inside an expanding sphere of empty space would NOT decrease with expansion. So if the sphere expands then, although R increases, M^2 increases even more, so the overall gravitational potential energy becomes larger, and thus more negative. Thus if the vacuum contains negative energy then as the sphere increases in size it becomes more negative and that means expansion is downhill, and so no work is used but instead work is produced. So in any universe in which vacuum energy dominates that universe will expand, it will fall outward and accelerate. 

Most physicists (but not all, see the next paragraph) think vacuum energy is what makes our universe accelerate. You might ask if the sphere gets larger what makes it get larger, where did that mass/energy come from? The answer is: It comes from the gravitational energy released as the sphere of vacuum energy falls outward. So at any point in this process if you add up all the positive kinetic energy and energy locked up in matter (remember E=MC^2) of the universe and all the negative potential gravitational energy of the universe you always get precisely zero.

As I said a minority of physicists reject the idea that Dark Energy is an intrinsic part of space itself and think it's really caused by a scalar (something that has a magnitude but no direction) quantum field that fills the entire universe, and they call that field "Quintessence". If Dark Energy is a field then that opens up the possibility of it changing with time. 

In just the last few months astronomers have found hints that Dark Energy might be getting weaker. The evidence is good enough to be interesting but not good enough to claim a discovery; IF it turns out to be true then Dark Energy cannot be an intrinsic part of space and some form of Quintessence must be true. But that's a big "IF".  

 John K Clark    See what's on my new list at  Extropolis 

tbi

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[John Clark]

On Mon, Jul 21, 2025 at 4:51 PM Brent Meeker <meeke...@gmail.com> wrote:

>> The gravitational potential energy of a sphere of particles of matter like sand is always negative, this is true in Newtonian Physics and remains true in General Relativity, so the gravitational potential energy of a sphere of particles of mass-energy M and radius R is PE= (-G*M^2)/R  where G is the gravitational constant. It’s important to note that this is negative energy, so the larger R gets the closer the potential energy gets to zero, and if it was at infinity it would be precisely zero. 
If the sphere expands and is made of sand, which is normal matter, then M stays the same but R increases, so the gravitational potential energy becomes less negative and more positive, and that means it's uphill; It would take an external expenditure of work to do that, so if you let the sphere go to rest it would fall inward as you'd expect.

> But if the total energy, gravitational potential plus sand kinetic, is zero

That would be true only if you assume that empty space contains energy and is the source of the acceleration of the universe, and while that's not a crazy assumption to make it's far from a proven fact.   

 

> then the sphere will expand forever but with a rate asymptotically approaching zero.

If empty space contains energy then the universe will not only expand forever it will accelerate forever, BUT the rate of acceleration will be constant, there would be no jerk, so there would be no Big Rip. But if a scalar field like Quintessence is the source of Dark Energy then a Big Rip would be possible, in fact a whole lot of  different things would be possible.  

John K Clark    See what's on my new list at  Extropolis 

667

[Alan Grayson]

I think I get it. Although light from ancient galaxies left those galaxies in the distant past, the red shift we observe reflects the expansion of the cosmos since then, and represents their recessional velocity at this time, NOW. This is consistent with Hubble's law, which tells us how fast galaxies outside the local group are receding in real time, NOW. AG 

noo

[John Clark]

On Tue, Jul 22, 2025 at 3:53 PM Alan Grayson <agrays...@gmail.com> wrote:

>I think I get it. Although light from ancient galaxies left those galaxies in the distant past, the red shift we observe reflects the expansion of the cosmos since then, and represents their recessional velocity at this time, NOW. This is consistent with Hubble's law, which tells us how fast galaxies outside the local group are receding in real time, NOW. AG 

Yes, but you have to be careful with "recessional velocity" because in cosmology the term can be ambiguous; sometimes it means how fast an object is moving away from us through space, and sometimes it means how fast the space between us and the object is expanding. I think cosmologists should have two different words for those two different things but unfortunately they don't.  

John K Clark    See what's on my new list at  Extropolis

&,s

[Alan Grayson]

Now I'm not sure I understand this. If we observe large red shifts from distant galaxies, how can we be sure most, or all of it is the result of spatial expansion, and not relative motion early on? Also, how can the red shift indicate recessional velocity NOW? Suppose the universe suddenly stopped expanding. Wouldn't we have to wait billions of years to observe that? It couldn't be observed NOW. AG

[John Clark]

On Sat, Aug 2, 2025 at 6:00 AM Alan Grayson <agrays...@gmail.com> wrote:

If we observe large red shifts from distant galaxies, how can we be sure most, or all of it is the result of spatial expansion, and not relative motion early on?

We observe that the more distant a galaxy is, the larger its redshift is. If that redshift is caused by the movement of a galaxy through space and not by the expansion of space itself then the only logical conclusion you could make is that Galileo was wrong and the medieval theologians were right, the Earth really is the center of the universe. Is there an idea you'd be willing to die on the hill for?  

 Also, how can the red shift indicate recessional velocity NOW?

If earth is not the center of the universe then redshift does not indicate recessional velocity at all, not now nor at other time  

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[John Clark]

 > Also, how can the red shift indicate recessional velocity NOW?

If Earth is not the center of the universe then redshift does not indicate a recessional velocity at all, not now nor at any other time, instead redshift is an indicator of how much space has expanded between now and the Big Bang.  

 

John K Clark    See what's on my new list at  Extropolis

xxx

[Alan Grayson]

I anticipated that answer but it doesn't work. Right now it appears that all galaxies other than the local group, are receding from us, and they are.  The exact same condition could have been operating in the very early universe due to relative spatial motion, placing Earth at the center of the universe. How to prove otherwise? AG

xxx

[John Clark]

On Sat, Aug 2, 2025 at 2:59 PM Alan Grayson <agrays...@gmail.com> wrote:

> Right now it appears that all galaxies other than the local group, are receding from us, and they are.  The exact same condition could have been operating in the very early universe due to relative spatial motion, placing Earth at the center of the universe. How to prove otherwise? 

Proof? Mathematicians prove things, physicists and astronomers do not. Instead they give ideas various degrees of credence. So it all comes down to one thing, is Earth being the center of the universe an idea you're willing to die on? Very few people are.  

Maybe Bishop Ussher was right and God created the universe on October 23, 4004 BC, and at the same time He created dinosaur bones and made them look like they were millions of years old to test our faith. Or maybe the universe only came into being 10 minutes ago and all our memories older than that are false memories God created to, you guessed it, test our faith. But scientists don't give either of those theories much credence, and neither do I, however they are no crazier than the Earth being at the center of the universe. 

 John K Clark    See what's on my new list at  Extropolis

ev1

[Alan Grayson]

On Saturday, August 2, 2025 at 1:23:36 PM UTC-6 John Clark wrote:

On Sat, Aug 2, 2025 at 2:59 PM Alan Grayson <agrays...@gmail.com> wrote:

> Right now it appears that all galaxies other than the local group, are receding from us, and they are.  The exact same condition could have been operating in the very early universe due to relative spatial motion, placing Earth at the center of the universe. How to prove otherwise? 

Proof? Mathematicians prove things, physicists and astronomers do not. Instead they give ideas various degrees of credence. So it all comes down to one thing, is Earth being the center of the universe an idea you're willing to die on? Very few people are.  

Mathematicians, and physicists, have proven many things about, for example, Hilbert spaces. In any event, if the universe ceased expanding, the indication from distant galaxies wouldn't reach us for billions of years. How then can we know these galaxies are receding rapidly NOW from their red shifts? AG 

[Alan Grayson]

On Saturday, August 2, 2025 at 1:43:13 PM UTC-6 Alan Grayson wrote:

On Saturday, August 2, 2025 at 1:23:36 PM UTC-6 John Clark wrote:

On Sat, Aug 2, 2025 at 2:59 PM Alan Grayson <agrays...@gmail.com> wrote:

> Right now it appears that all galaxies other than the local group, are receding from us, and they are.  The exact same condition could have been operating in the very early universe due to relative spatial motion, placing Earth at the center of the universe. How to prove otherwise? 

Proof? Mathematicians prove things, physicists and astronomers do not. Instead they give ideas various degrees of credence. So it all comes down to one thing, is Earth being the center of the universe an idea you're willing to die on? Very few people are.  

Mathematicians, and physicists, have proven many things about, for example, Hilbert spaces. In any event, if the universe ceased expanding, the indication from distant galaxies wouldn't reach us for billions of years. How then can we know these galaxies are receding rapidly NOW from their red shifts? AG 

I don't think the Earth is at the center of the universe, which almost certainly has no center (an unproven and perhaps unprovable hypothesis). Nonetheless, I think you fail to get the significance of my comment. IIUC, you claim that the red shift observed in light emitted from distant galaxies, tells us the re ssional rate of those galaxies NOW. But if the expansion were to suddenly cease, so would their red shifts, and we couldn't observe that until billions of years after it occurred, the time required for their light to reach us. That being the case, how is it possible to know their recessional velocity NOW by measuring the red shift observed by light reaching us NOW? AG

Hubble's Law seems to tell us that galaxies far far away, were receding much more rapidly than they are NOW, which you dispute. You claim they were receding from each other very slowly in very early times. But from a geometric pov, the more remote a galaxy is, that is, at a very early time, the greater is its recessional velocity. So your claim seems inconsistent with the geometric pov, where we can imagine a spherical universe with, for the sake of argument, is uniformly expanding, and the more distant a galaxy is, the more rapid is its recessional velocity. AG 

[John Clark]

On Sun, Aug 3, 2025 at 11:12 PM Alan Grayson <agrays...@gmail.com> wrote:

> I don't think the Earth is at the center of the universe,

Well I'm glad of that, at least we don't have to rehash a 482 year old controversy, we only have to rehash a 120 year old controversy.  

 

 > I think you fail to get the significance of my comment. IIUC,

You're right, in the context of Big Bang cosmology I don't get the significance of the International Islamic University Chittagong. And you've forgotten IHA.

 

> you claim that the red shift observed in light emitted from distant galaxies, tells us the ressional rate of those galaxies NOW.

NO! I do NOT make that claim as I explained in a post I sent just the day before yesterday:

"If Earth is not the center of the universe then redshift does not indicate a recessional velocity at all, not now nor at any other time, instead redshift is an indicator of how much space has expanded between now and the Big Bang." 

After reading your above statement I stopped reading the rest of your post because after just glancing at it I could see it was littered with the word "now" all written in big capital letters.  And this is a good example of why debating with you is such a frustrating experience.  

Our telescopes measure redshift, and there are only 3 ways an object like a galaxy can produce a redshift :

1) An enormously powerful gravitational field. 

2) The movement through space of a galaxy away from us. 

3) The expansion of space itself. 

It can't be #1 because if galaxies had gravitational fields that strong we would see billions of times more gravitational lensing than we do. 

Assuming Galileo was right and the Earth is not the center of the universe then it can't be #2, because if it was we'd expect to find an equal number of redshifted and blueshifted galaxies, but that's not what we see. And we'd expect to find no relationship between the amount of shifting of spectral lines and the distance to a Galaxy, but we do find such a relationship. And from the study of nearby galaxies we have a good understanding of how fast galaxies are moving through space relative to each other, and that speed is far far too slow to explain the huge redshifting that we observe. 

So if it can't be #1 or #2 it must be #3. As Sherlock Holmes said: 

"When you have eliminated the impossible, whatever remains, however improbable, must be the truth"

 John K Clark    See what's on my new list at  Extropolis

shq

[Alan Grayson]

On Monday, August 4, 2025 at 6:07:52 AM UTC-6 John Clark wrote:

On Sun, Aug 3, 2025 at 11:12 PM Alan Grayson <agrays...@gmail.com> wrote:

> I don't think the Earth is at the center of the universe,

Well I'm glad of that, at least we don't have to rehash a 482 year old controversy, we only have to rehash a 120 year old controversy.  

 

 > I think you fail to get the significance of my comment. IIUC,

You're right, in the context of Big Bang cosmology I don't get the significance of the International Islamic University Chittagong. And you've forgotten IHA.

Since you know that acronym, what's the value in playing dumb? AG

 

> you claim that the red shift observed in light emitted from distant galaxies, tells us the ressional rate of those galaxies NOW.

NO! I do NOT make that claim as I explained in a post I sent just the day before yesterday:

See your post dated Jul 23, 2025, 4:44:08 AM, where you seem to make that claim. But since you don't, we can move on. AG

"If Earth is not the center of the universe then redshift does not indicate a recessional velocity at all, not now nor at any other time, instead redshift is an indicator of how much space has expanded between now and the Big Bang." 

OK, then why does Hubble's Law seem to indicate the universe was expanding rapidly, say around 10 billion years ago indicated by very high red shift, and slowed in more recent times, presumably due to gravity, but the geometric argument shows the opposite; that even if the expansion is uniform, distant galaxies have increasing recessional velocities? TY, AG 

[Alan Grayson]

On Monday, August 4, 2025 at 7:02:03 AM UTC-6 Alan Grayson wrote:

On Monday, August 4, 2025 at 6:07:52 AM UTC-6 John Clark wrote:

On Sun, Aug 3, 2025 at 11:12 PM Alan Grayson <agrays...@gmail.com> wrote:

> I don't think the Earth is at the center of the universe,

Well I'm glad of that, at least we don't have to rehash a 482 year old controversy, we only have to rehash a 120 year old controversy.  

 

 > I think you fail to get the significance of my comment. IIUC,

You're right, in the context of Big Bang cosmology I don't get the significance of the International Islamic University Chittagong. And you've forgotten IHA.

Since you know that acronym, what's the value in playing dumb? AG

 

> you claim that the red shift observed in light emitted from distant galaxies, tells us the ressional rate of those galaxies NOW.

NO! I do NOT make that claim as I explained in a post I sent just the day before yesterday:

See your post dated Jul 23, 2025, 4:44:08 AM, where you seem to make that claim. But since you don't, we can move on. AG

"If Earth is not the center of the universe then redshift does not indicate a recessional velocity at all, not now nor at any other time, instead redshift is an indicator of how much space has expanded between now and the Big Bang." 

OK, then why does Hubble's Law seem to indicate the universe was expanding rapidly, say around 10 billion years ago indicated by very high red shift, and slowed in more recent times, presumably due to gravity, but the geometric argument shows the opposite; that even if the expansion is uniform, distant galaxies have increasing recessional velocities? TY, AG 

I think I made an error immediately above. Hubble's Law and the geometric argument are not in contradiction with each other. Both indicate, IMO, that the further back in time we look, the faster is the rate of expansion. AG 

Recall, that you claimed the rate of expansion was slow in the very early universe, but since the red shifts are very large, do you agree that the rate of expansion was also large, not small as you previously claimed? AG 

[John Clark]

On Mon, Aug 4, 2025 at 9:02 AM Alan Grayson <agrays...@gmail.com> wrote:

 >>> I think you fail to get the significance of my comment. IIUC,

>> You're right, in the context of Big Bang cosmology I don't get the significance of the International Islamic University Chittagong. And you've forgotten IHA.

> Since you know that acronym,

Actually I don't, and apparently neither does Google. I'm afraid I'm not up-to-date on the latest teenage text messaging slang. At one time I may have known what it meant but my memory capacity is not infinite so it may have been erased to make room for more important information. And speaking of forgetting, you have forgotten IHA. 

>why does Hubble's Law seem to indicate the universe was expanding rapidly, say around 10 billion years ago indicated by very high red shift, ,

Yes the universe was expanding rapidly but that's not the important thing, the important thing is that it was ACCELERATING rapidly, and nobody knows why, it's probably the biggest unanswered question in physics. The name we have given for whatever mysterious thing is causing that acceleration is "dark energy". We had to call it something and that name is as good as any.   

> and slowed in more recent times,

About 9 billion years after the Big Bang (5 billion years ago) about the time the solar system started to form, the RATE of acceleration (the technical term for that is "jerk") INCREASED, most think that is because as the volume of the universe increased the density of matter, which wants to slow things down, became diluted, but the density of dark energy, which ones things to move faster, did not become diluted. And it wouldn't become diluted if dark energy was an intrinsic property of space itself.   

>distant galaxies have increasing recessional velocities

No! Distant galaxies have increased their redshift, and there is no way recessional velocities can explain that redshift. 

 John K Clark    See what's on my new list at  Extropolis

isr

 

After reading your above statement I stopped reading the rest of your post because after just glancing at it I could see it was littered with the word "now" all written in big capital letters.  And this is a good example of why debating with you is such a frustrating experience.  

Our telescopes measure redshift, and there are only 3 ways an object like a galaxy can produce a redshift :

1) An enormously powerful gravitational field. 

2) The movement through space of a galaxy away from us. 

3) The expansion of space itself. 

It can't be #1 because if galaxies had gravitational fields that strong we would see billions of times more gravitational lensing than we do. 

Assuming Galileo was right and the Earth is not the center of the universe then it can't be #2, because if it was we'd expect to find an equal number of redshifted and blueshifted galaxies, but that's not what we see. And we'd expect to find no relationship between the amount of shifting of spectral lines and the distance to a Galaxy, but we do find such a relationship. And from the study of nearby galaxies we have a good understanding of how fast galaxies are moving through space relative to each other, and that speed is far far too slow to explain the huge redshifting that we observe. 

So if it can't be #1 or #2 it must be #3. As Sherlock Holmes said: 

"When you have eliminated the impossible, whatever remains, however improbable, must be the truth"

 

shq

[Alan Grayson]

On Monday, August 4, 2025 at 8:13:08 AM UTC-6 John Clark wrote:

On Mon, Aug 4, 2025 at 9:02 AM Alan Grayson <agrays...@gmail.com> wrote:

 >>> I think you fail to get the significance of my comment. IIUC,

>> You're right, in the context of Big Bang cosmology I don't get the significance of the International Islamic University Chittagong. And you've forgotten IHA.

> Since you know that acronym,

Actually I don't, and apparently neither does Google. I'm afraid I'm not up-to-date on the latest teenage text messaging slang. At one time I may have known what it meant but my memory capacity is not infinite so it may have been erased to make room for more important information. And speaking of forgetting, you have forgotten IHA. 

It's  a common acronyn; been around for years, and I am sure Google has it listed. You needn't invoke nasty "teenage" crap. AG 

>why does Hubble's Law seem to indicate the universe was expanding rapidly, say around 10 billion years ago indicated by very high red shift, ,

Yes the universe was expanding rapidly

But earlier you insisted the early universe was expanding SLOWLY, and hence accelerating SLOWLY. This is what faked me out. AG

 

but that's not the important thing, the important thing is that it was ACCELERATING rapidly, and nobody knows why, it's probably the biggest unanswered question in physics. The name we have given for whatever mysterious thing is causing that acceleration is "dark energy". We had to call it something and that name is as good as any.   

> and slowed in more recent times,

About 9 billion years after the Big Bang (5 billion years ago) about the time the solar system started to form, the RATE of acceleration (the technical term for that is "jerk") INCREASED, most think that is because as the volume of the universe increased the density of matter, which wants to slow things down, became diluted, but the density of dark energy, which ones things to move faster, did not become diluted. And it wouldn't become diluted if dark energy was an intrinsic property of space itself.   

>distant galaxies have increasing recessional velocities

No! Distant galaxies have increased their redshift, and there is no way recessional velocities can explain that redshift. 

Asymmetric recessional velocity, due to expansion, explains it. It's a geometric effect of expansion. AG 

 John K Clark    See what's on my new list at  Extropolisr