Does Hubble's Law tell us how rapidly the universe expanded in its very early history?

[Alan Grayson]

I think not. It just tell us how rapidly it is expanding at different distance, but at the same time, NOW. So, there is no basis for the claim it was expanding very slowly in its very early history. AG

[Alan Grayson]

On Sunday, August 24, 2025 at 10:03:20 PM UTC-6 Alan Grayson wrote:

I think not. It just tell us how rapidly it is expanding at different distance, but at the same time, NOW. So, there is no basis for the claim it was expanding very slowly in its very early history. AG

Clark, what is the logic underlying your claim that in the very early universe, the universe was expanding very slowly? The way I see it, from Hubble's law we can't make any conclusion about the expansion rate of the very early universe.  TY, AG

[Alan Grayson]

Once we know the universe is expanding, and the rate is somewhere between 67 and 73 km/sec/mpsec, can't we infer the rate was higher in the very early universe since it has slowed since then due to gravitational attraction? IOW, the rate was more rapid in the early universe than at present. Yet you claim it was much lower. What's your reasoning? TY, AG 

[Alan Grayson]

Clark; my comment above makes sense. How can it be denied, that the very early universe expanded rapidly, not slowly? Cat got your tongue? AG 

[John Clark]

On Wed, Aug 27, 2025 at 6:15 AM Alan Grayson <agrays...@gmail.com> wrote:

Clark, what is the logic underlying your claim that in the very early universe, the universe was expanding very slowly?

I've mentioned the following before. You ask a question. I take the time to answer your question and try hard to write as clearly as possible. You then ask the EXACT same question again without challenging or mentioning anything I said or even given an indication that you had read my previous answer. I find such behavior annoying and I don't believe my attitude is unreasonable. 

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

ngf

On Sunday, August 24, 2025 at 10:03:20 PM UTC-6 Alan Grayson wrote:

I think not. It just tell us how rapidly it is expanding at different distance, but at the same time, NOW. So, there is no basis for the claim it was expanding very slowly in its very early history. AG

Clark, what is the logic underlying your claim that in the very early universe, the universe was expanding very slowly? The way I see it, from Hubble's law we can't make any conclusion about the expansion rate of the very early universe.  TY, AG

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[Alan Grayson]

On Thursday, August 28, 2025 at 2:06:35 PM UTC-6 John Clark wrote:

On Wed, Aug 27, 2025 at 6:15 AM Alan Grayson <agrays...@gmail.com> wrote:

Clark, what is the logic underlying your claim that in the very early universe, the universe was expanding very slowly?

I've mentioned the following before. You ask a question. I take the time to answer your question and try hard to write as clearly as possible. You then ask the EXACT same question again without challenging or mentioning anything I said or even given an indication that you had read my previous answer. I find such behavior annoying and I don't believe my attitude is unreasonable. 

Evasive BS!  AG

n

[Alan Grayson]

As I recall, you made the emphatic claim, at least twice, that in the very early universe (but after the galaxies formed), that the galaxies were closely situated, and receded from each other at low velocities. I do NOT recall any proof of concept. On the other hand, I gave a basic argument that in fact the rate of recession had to be rapid at that time, since it's now between 67 and 73 km/sec/mpsec, and was SLOWED since that time by gravity, which, last I heard is attractive, so it would slow the rate of expansion. I'd be interested in seeing again what you claim was your proof. AG 

[John Clark]

On Fri, Aug 29, 2025 at 2:09 AM Alan Grayson <agrays...@gmail.com> wrote:

> As I recall, you made the emphatic claim, at least twice, that in the very early universe (but after the galaxies formed), that the galaxies were closely situated, and receded from each other at low velocities. I do NOT recall any proof of concept.

Astronomers have observational evidence that the universe started to accelerate about 5 billion years ago, 9 billion years after the big bang. If something is accelerating that means it's getting faster. Therefore 5 billion years ago, before that acceleration started, galaxies must've been moving away from each other slower than they are now. 

 

> On the other hand, I gave a basic argument that in fact the rate of recession had to be rapid at that time, since it's now between 67 and 73 km/sec/mpsec, and was SLOWED since that time by gravity, which, last I heard is attractive. so it would slow the rate of expansion.

 

Have you also heard that there is a thing called "Dark Energy"? I've said all this before but I'll say it one more time. We don't know much about it but one of the few things we do know is that Dark Energy is a repulsive force which means it causes things to SPEED UP. Most think Dark Energy is a property of space itself, that's why for the first 9 billion years of the universe's existence Dark Energy didn't have much effect on things, back then the speed of recession between galaxies was slowing down due to gravity just as you'd expect. But as the galaxys expanded the density of matter decreased, and therefore the force of gravity trying to slow things down also decreased. 

However, the expansion of space means more space is being created, and if Dark Energy is a property of space itself then, unlike gravity, it is NOT being diluted. The force of Dark Energy trying to speed things up remained constant, but the force of gravity, trying to slow things down, kept getting weaker because the density of matter kept getting lower. Dark Energy became stronger than gravity 5 billion years ago and remains stronger to this day. 

> I'd be interested in seeing again what you claim was your proof. AG 

As I've mentioned before, a scientist can prove that something is wrong and he can show that something is probably right, but proving that something is absolutely correct can only be found in the realm of pure mathematics, not in physics or in any other branch of science.  

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

4vr

[Alan Grayson]

On Friday, August 29, 2025 at 5:15:32 AM UTC-6 John Clark wrote:

On Fri, Aug 29, 2025 at 2:09 AM Alan Grayson <agrays...@gmail.com> wrote:

> As I recall, you made the emphatic claim, at least twice, that in the very early universe (but after the galaxies formed), that the galaxies were closely situated, and receded from each other at low velocities. I do NOT recall any proof of concept.

Astronomers have observational evidence that the universe started to accelerate about 5 billion years ago, 9 billion years after the big bang.

It started to accelerate, OR was already accelerating 5 billion years ago, and then accelerated more? This is important for your argument, but I've never heard that before -- that's there's EVIDENCE for your claim (that it STARTED to accelerate 5 billion years ago). AG

 

If something is accelerating that means it's getting faster. Therefore 5 billion years ago, before that acceleration started, galaxies must've been moving away from each other slower than they are now. 

 

> On the other hand, I gave a basic argument that in fact the rate of recession had to be rapid at that time, since it's now between 67 and 73 km/sec/mpsec, and was SLOWED since that time by gravity, which, last I heard is attractive. so it would slow the rate of expansion.

 

Have you also heard that there is a thing called "Dark Energy"? I've said all this before but I'll say it one more time. We don't know much about it but one of the few things we do know is that Dark Energy is a repulsive force which means it causes things to SPEED UP. Most think Dark Energy is a property of space itself, that's why for the first 9 billion years of the universe's existence Dark Energy didn't have much effect on things, back then the speed of recession between galaxies was slowing down due to gravity just as you'd expect. But as the galaxys expanded the density of matter decreased, and therefore the force of gravity trying to slow things down also decreased. 

Dark Energy may or may not exist, but if it does and is responsible for the speeding up, it doesn't imply the galaxies were receding from each other slowly before DE speeded the expansion. The receding could have been slow before DE became a factor, OR it could have been receding rapidly and that rate was increased by DE. IOW, we just don't know whether the expansion started slowly or rapidly. AG  

However, the expansion of space means more space is being created, and if Dark Energy is a property of space itself then, unlike gravity, it is NOT being diluted. The force of Dark Energy trying to speed things up remained constant, but the force of gravity, trying to slow things down, kept getting weaker because the density of matter kept getting lower. Dark Energy became stronger than gravity 5 billion years ago and remains stronger to this day. 

> I'd be interested in seeing again what you claim was your proof. AG 

As I've mentioned before, a scientist can prove that something is wrong and he can show that something is probably right, but proving that something is absolutely correct can only be found in the realm of pure mathematics, not in physics or in any other branch of science.  

Actually, sometimes even in pure mathematics we can't always reach absolute conclusions, a good example of which is the CONTINUUM HYPOTHESIS. AG 

4vr

[John Clark]

On Fri, Aug 29, 2025 at 8:17 AM Alan Grayson <agrays...@gmail.com> wrote:

It started to accelerate, OR was already accelerating 5 billion years ago, and then accelerated more?

Not counting the period of inflation which only lasted a tiny fraction of a nanosecond, during the first 9 billion years of the universe's existence its expansion was decelerating, but then about 5 billion years ago things changed and it started to accelerate for reasons that I have already mentioned.  

> This is important for your argument, but I've never heard that before 

You have just confirmed something that I have long suspected, you do not read my posts because I've certainly mentioned it before.  Below are the original articles announcing the discovery made independently by two teams back in 1998 that they both received Nobel prizes for.

Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant

MEASUREMENTS OF Ω  FROM 42 HIGH-REDSHIFT SUPERNOVAE

 

> Dark Energy may or may not exist,

Dark energy is the name we have given to whatever is accelerating the universe, we had to call it something. The universe is definitely accelerating so Dark Energy, whatever it is, definitely exists.  

  > if it does and is responsible for the speeding up, it doesn't imply the galaxies were receding from each other slowly before DE speeded the expansion.

Huh?  If you make a thing move faster then you make it move faster. And the great thing about tautologies is that they are ALWAYS true. 

> Actually, sometimes even in pure mathematics we can't always reach absolute conclusions, a good example of which is the CONTINUUM HYPOTHESIS. AG 

But it has been proven you can assume  that the continuum hypothesis is true or you can assume that the continuum hypothesis is not true, but neither assumption will produce a contradiction to existing mathematics. It doesn't matter, so to my mind that indicates that the continuum hypothesis is just not very important. 

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

f8q

[Alan Grayson]

On Friday, August 29, 2025 at 8:07:55 AM UTC-6 John Clark wrote:

On Fri, Aug 29, 2025 at 8:17 AM Alan Grayson <agrays...@gmail.com> wrote:

It started to accelerate, OR was already accelerating 5 billion years ago, and then accelerated more?

Not counting the period of inflation which only lasted a tiny fraction of a nanosecond, during the first 9 billion years of the universe's existence its expansion was decelerating, but then about 5 billion years ago things changed and it started to accelerate for reasons that I have already mentioned.  

> This is important for your argument, but I've never heard that before 

You have just confirmed something that I have long suspected, you do not read my posts because I've certainly mentioned it before. 

Do us all a big favor and cease your BS'ing. Those articles below I haven't read because they assert what I already knew; that two teams discovered the universe was accelerating in 1998. Where is the EVIDENCE in your claim above, that the rate of expansion was SLOWING from the time the galaxies formed, for about 9 billion years? I don't recall any of your posts where you stated or proved that. AG 

 

Below are the original articles announcing the discovery made independently by two teams back in 1998 that they both received Nobel prizes for.

Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant

MEASUREMENTS OF Ω  FROM 42 HIGH-REDSHIFT SUPERNOVAE

 

> Dark Energy may or may not exist,

Dark energy is the name we have given to whatever is accelerating the universe, we had to call it something. The universe is definitely accelerating so Dark Energy, whatever it is, definitely exists.  

  > if it does and is responsible for the speeding up, it doesn't imply the galaxies were receding from each other slowly before DE speeded the expansion.

Huh?  If you make a thing move faster then you make it move faster. And the great thing about tautologies is that they are ALWAYS true. 

Obviously, you don't understand what I wrote, and it's certainly not a tautology. AG 

> Actually, sometimes even in pure mathematics we can't always reach absolute conclusions, a good example of which is the CONTINUUM HYPOTHESIS. AG 

But it has been proven you can assume  that the continuum hypothesis is true or you can assume that the continuum hypothesis is not true, but neither assumption will produce a contradiction to existing mathematics. It doesn't matter, so to my mind that indicates that the continuum hypothesis is just not very important. 

What's "important" here is in the mind of mathematicans. And IMO you've misstated the result. AG

[Alan Grayson]

On Friday, August 29, 2025 at 1:09:46 PM UTC-6 Alan Grayson wrote:

On Friday, August 29, 2025 at 8:07:55 AM UTC-6 John Clark wrote:

On Fri, Aug 29, 2025 at 8:17 AM Alan Grayson <agrays...@gmail.com> wrote:

It started to accelerate, OR was already accelerating 5 billion years ago, and then accelerated more?

Not counting the period of inflation which only lasted a tiny fraction of a nanosecond, during the first 9 billion years of the universe's existence its expansion was decelerating, but then about 5 billion years ago things changed and it started to accelerate for reasons that I have already mentioned.  

> This is important for your argument, but I've never heard that before 

You have just confirmed something that I have long suspected, you do not read my posts because I've certainly mentioned it before. 

Do us all a big favor and cease your BS'ing. Those articles below I haven't read because they assert what I already knew; that two teams discovered the universe was accelerating in 1998. Where is the EVIDENCE in your claim above, that the rate of expansion was SLOWING from the time the galaxies formed, for about 9 billion years? I don't recall any of your posts where you stated or proved that. AG 

Sure, the expansion was slowing due to gravity, but this doesn't necessarily mean the rate was initially slow, which was your UNPROVEN claim! WTF. AG 

[John Clark]

On Fri, Aug 29, 2025 at 3:09 PM Alan Grayson <agrays...@gmail.com> wrote:

> Do us all a big favor and cease your BS'ing. Those articles below I haven't read because they assert what I already knew; that two teams discovered the universe was accelerating in 1998. Where is the EVIDENCE in your claim above, that the rate of expansion was SLOWING from the time the galaxies formed, for about 9 billion years? I don't recall any of your posts where you stated or proved that. AG 

The following quote is from  Expansion of the universe :

 

"The very earliest expansion, called inflation saw the universe suddenly expand by a factor of at least 10²⁶ in every direction about 10⁻³² of a second after the Big Bang. Cosmic expansion subsequently decelerated to much slower rates, until around 9.8 billion years after the Big Bang (4 billion years ago) it began to gradually 

expand more quickly, and is still doing so." 

The following quote is from Accelerating expansion of the universe:

"The accelerated expansion of the universe is thought to have begun since the universe entered its dark-energy-dominated era roughly 5 billion years ago"

 

> Dark Energy may or may not exist,

>Dark energy is the name we have given to whatever is accelerating the universe, we had to call it something. The universe is definitely accelerating so Dark Energy, whatever it is, definitely exists.  

  >>> if it does and is responsible for the speeding up, it doesn't imply the galaxies were receding from each other slowly before DE speeded the expansion.

>>Huh?  If you make a thing move faster then you make it move faster. And the great thing about tautologies is that they are ALWAYS true. 

 

>Obviously, you don't understand what I wrote,

True, but that's not the big question. Do you understand what you wrote?  

 

> and it's certainly not a tautology. AG 

If it looks like a duck and walks like a duck and quacks like a duck then it's a duck.  

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

iad

[Alan Grayson]

On Saturday, August 30, 2025 at 4:34:30 AM UTC-6 John Clark wrote:

On Fri, Aug 29, 2025 at 3:09 PM Alan Grayson <agrays...@gmail.com> wrote:

> Do us all a big favor and cease your BS'ing. Those articles below I haven't read because they assert what I already knew; that two teams discovered the universe was accelerating in 1998. Where is the EVIDENCE in your claim above, that the rate of expansion was SLOWING from the time the galaxies formed, for about 9 billion years? I don't recall any of your posts where you stated or proved that. AG 

The following quote is from  Expansion of the universe :

 

"The very earliest expansion, called inflation saw the universe suddenly expand by a factor of at least 10²⁶ in every direction about 10⁻³² of a second after the Big Bang. Cosmic expansion subsequently decelerated to much slower rates, until around 9.8 billion years after the Big Bang (4 billion years ago) it began to gradually 

expand more quickly, and is still doing so." 

The following quote is from Accelerating expansion of the universe:

"The accelerated expansion of the universe is thought to have begun since the universe entered its dark-energy-dominated era roughly 5 billion years ago"

I never disputed that conclusion; only yours, that it implies that after the galaxies formed, the universe was expanding very slowly. Sure, after that the expansion slowed due to gravity, but the discovery of the accelerated expansion says NOTHING about the much earlier rate of expansion. AG 

 

> Dark Energy may or may not exist,

>Dark energy is the name we have given to whatever is accelerating the universe, we had to call it something. The universe is definitely accelerating so Dark Energy, whatever it is, definitely exists.  

  >>> if it does and is responsible for the speeding up, it doesn't imply the galaxies were receding from each other slowly before DE speeded the expansion.

>>Huh?  If you make a thing move faster then you make it move faster. And the great thing about tautologies is that they are ALWAYS true. 

 

>Obviously, you don't understand what I wrote,

True, but that's not the big question. Do you understand what you wrote?  

 

> and it's certainly not a tautology. AG 

If it looks like a duck and walks like a duck and quacks like a duck then it's a duck.  

Cease with the riddles and say explicitly what you mean. I never posted a tautology! AG 

[John Clark]

On Sat, Aug 30, 2025 at 6:56 AM Alan Grayson <agrays...@gmail.com> wrote:

The following quote is from  Expansion of the universe :

 

"The very earliest expansion, called inflation saw the universe suddenly expand by a factor of at least 10²⁶ in every direction about 10⁻³² of a second after the Big Bang. Cosmic expansion subsequently decelerated to much slower rates, until around 9.8 billion years after the Big Bang (4 billion years ago) it began to gradually expand more quickly, and is still doing so." 

The following quote is from Accelerating expansion of the universe:

"The accelerated expansion of the universe is thought to have begun since the universe entered its dark-energy-dominated era roughly 5 billion years ago"

> I never disputed that conclusion; only yours, that it implies that after the galaxies formed, the universe was expanding very slowly.

Expanding "very slowly" compared with the expansion of the universe during inflation certainly. I will now make a statement that you dispute that I am nevertheless absolutely certain is true: 

Today galaxies are expanding faster than they were before galaxies started expanding faster. 

The reason I would be willing to bet my life on the above statement being true is because all tautologies are true.

 

> Sure, after that the expansion slowed due to gravity, but the discovery of the accelerated expansion says NOTHING about the much earlier rate of expansion. AG 

Yet more evidence that you don't read what I write, not even the parts that I underline. 

"Cosmic expansion subsequently decelerated to much slower rates, until around 9.8 billion years after the Big Bang (4 billion years ago) it began to gradually expand more quickly, and is still doing so." 

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

emq

[Alan Grayson]

On Saturday, August 30, 2025 at 5:20:04 AM UTC-6 John Clark wrote:

On Sat, Aug 30, 2025 at 6:56 AM Alan Grayson <agrays...@gmail.com> wrote:

The following quote is from  Expansion of the universe :

 

"The very earliest expansion, called inflation saw the universe suddenly expand by a factor of at least 10²⁶ in every direction about 10⁻³² of a second after the Big Bang. Cosmic expansion subsequently decelerated to much slower rates, until around 9.8 billion years after the Big Bang (4 billion years ago) it began to gradually expand more quickly, and is still doing so." 

The following quote is from Accelerating expansion of the universe:

"The accelerated expansion of the universe is thought to have begun since the universe entered its dark-energy-dominated era roughly 5 billion years ago"

> I never disputed that conclusion; only yours, that it implies that after the galaxies formed, the universe was expanding very slowly.

Expanding "very slowly" compared with the expansion of the universe during inflation certainly. I will now make a statement that you dispute that I am nevertheless absolutely certain is true: 

Today galaxies are expanding faster than they were before galaxies started expanding faster. 

The reason I would be willing to bet my life on the above statement being true is because all tautologies are true.

What tautology are you referring to? You really need to get your act together and cease with your foolish accusations. AG  

> Sure, after that the expansion slowed due to gravity, but the discovery of the accelerated expansion says NOTHING about the much earlier rate of expansion. AG 

Yet more evidence that you don't read what I write, not even the parts that I underline. 

More mind-reading by the a'hole-in-chief. AG 

"Cosmic expansion subsequently decelerated to much slower rates, until around 9.8 billion years after the Big Bang (4 billion years ago) it began to gradually expand more quickly, and is still doing so." 

Decelerated from what? That's the issue, in case you can't remember. Sure, I read it, several times in fact, but I see no EVIDENCE for the conclusion you've fallen in love with; that in the very early universe, the rate of expansion was very low. Do you know the difference between FACT and CONJECTURE? AG 

[Alan Grayson]

On Saturday, August 30, 2025 at 5:33:59 AM UTC-6 Alan Grayson wrote:

On Saturday, August 30, 2025 at 5:20:04 AM UTC-6 John Clark wrote:

On Sat, Aug 30, 2025 at 6:56 AM Alan Grayson <agrays...@gmail.com> wrote:

The following quote is from  Expansion of the universe :

 

"The very earliest expansion, called inflation saw the universe suddenly expand by a factor of at least 10²⁶ in every direction about 10⁻³² of a second after the Big Bang. Cosmic expansion subsequently decelerated to much slower rates, until around 9.8 billion years after the Big Bang (4 billion years ago) it began to gradually expand more quickly, and is still doing so." 

The following quote is from Accelerating expansion of the universe:

"The accelerated expansion of the universe is thought to have begun since the universe entered its dark-energy-dominated era roughly 5 billion years ago"

If you believe the results from the JWST, galaxies formed very soon after the time of recombination, 378,000 years after the BB, say within a few hundred million years. The galaxies were very closely packed at that time, but their rate of separation, or shall we say expansion, cannot IMO be determined by the 1998 discovery. You prefer, and believe, the rate was very slow AT THAT TIME. But that's just your conjecture. I believe it was very rapid since the BB was likely a hugely violent event. But I can't prove that, and never claimed I could. AG 

[ilsa]

https://www.facebook.com/reel/24358065777213696/?mibextid=9drbnH&s=yWDuG2&fs=e

Ilsa Bartlett

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[Cosmin Visan]

All kinds of hallucinations that professors-priests call them "theory" in order to keep their jobs in order to have access to girls.

[Alan Grayson]

Sorry, but I'm still confused about what, exactly, Hubble's law is telling us. On its face, it's saying that on average, the farther away galaxies are, the faster is their recessional velocity. Does this mean that in the past, after the very short period of inflation ended, and ignoring 1998 measurements, they were receding faster than they are today? TY, AG

[Alan Grayson]

I think I get it. The recessional velocity is simply a function of distance, so regardless of the rate of expansion of the universe, the recessional velocity will keep increasing, but at different rates, depending on the rate of expansion and how distant a galaxy is. Even assuming the effect of gravity is to slow the rate of expansion, and even if that rate increases as shown by the 1998 measurements, the recessional velocity will increase or decrease in its RATE, but in absolute terms its value must increase if the universe continues to expand. In sum, although we're viewing those galaxies as they were billions of years ago, Hubble's law tells us how fast they are receding in the present, aka NOW. (This is what was puzzling me; whether or not the high recessional velocity of distant galaxies is occurring now or in the distant past.) Finally, since the galaxies were closely located relatively soon after inflation ended, the magnitude of mutual recessional velocity at that time was positive, but small. AG 

[Alan Grayson]

Clark; do me a favor and post if you agree with my analysis of Hubble's law. TY, AG 

[Alan Grayson]

On Sunday, August 24, 2025 at 10:03:20 PM UTC-6 Alan Grayson wrote:

I think not. It just tell us how rapidly it is expanding at different distance, but at the same time, NOW. So, there is no basis for the claim it was expanding very slowly in its very early history. AG

Wrong conclusion! Since galaxies far away are receding the faster than those close to us, Hubble's law also says that those close to us are receding more slowly than those farther away. So, since in the very early universe the galaxies were closely separated,  Hubble's law says they were receding from each other more slowly than today. AG 

[John Clark]

On Wed, Dec 3, 2025 at 6:08 AM Alan Grayson <agrays...@gmail.com> wrote:

On Sunday, August 24, 2025 at 10:03:20 PM UTC-6 Alan Grayson wrote:

 

I think not. It just tell us how rapidly it is expanding at different distance, but at the same time, NOW. So, there is no basis for the claim it was expanding very slowly in its very early history. AG

> Wrong conclusion! Since galaxies far away are receding the faster than those close to us, Hubble's law also says that those close to us are receding more slowly than those farther away since in the very early universe the galaxies were closely separated,  Hubble's law says they were receding from each other more slowly than today. AG 

I think you would be less confused if you forget about recessional velocity and forget about distance, strictly speaking Hubble's Law is about the relation between the amount of red shift we observe in the light spectrum of a galaxy and the amount of time it took for the light from that galaxy to reach us. If Hubble's Law indicates that it took a particular galaxy 10 billion years to reach us it would NOT be even  approximately correct to say that the galaxy is now 10 billion light years away, it would actually be much much further away than that; and it would also NOT be correct to say that when that light started its journey the Earth was 10 billion light years away, back then it was actually much less than that, or it would've been if Earth had existed 10 billion years ago, which it didn't. 

You've got to remember Einstein tells us there is a fundamental difference between:

1) Two objects moving through space away from each other. 

2) Space itself between two objects expanding. 

In cosmology only the second case is important. If we ignore the era of hyperinflation that ended about 10^-32 seconds after the big bang, for about 9 billion years after the Big Bang space was expanding much faster than it is now, but the rate of expansion was decreasing. About 5 billion years ago things changed, the rate of expansion started to increase, this would make sense IF Dark Energy is an intrinsic part of space because as space expands matter, which wants to retard the expansion gets diluted but space, which wants to increase the expansion, does not. 

However that might not be true, Dark Energy might not be caused by space itself, maybe it's produced by some sort of field that can change with time. Very recently there have been indications that the rate of change of the acceleration of the universe (believe it or not called a cosmic jerk) might be decreasing, but the evidence is not yet strong enough to claim a discovery.   

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

3//

[Alan Grayson]

On Wednesday, December 3, 2025 at 5:51:29 AM UTC-7 John Clark wrote:

On Wed, Dec 3, 2025 at 6:08 AM Alan Grayson <agrays...@gmail.com> wrote:

On Sunday, August 24, 2025 at 10:03:20 PM UTC-6 Alan Grayson wrote:

 

I think not. It just tell us how rapidly it is expanding at different distance, but at the same time, NOW. So, there is no basis for the claim it was expanding very slowly in its very early history. AG

> Wrong conclusion! Since galaxies far away are receding the faster than those close to us, Hubble's law also says that those close to us are receding more slowly than those farther away since in the very early universe the galaxies were closely separated,  Hubble's law says they were receding from each other more slowly than today. AG 

I think you would be less confused if you forget about recessional velocity and forget about distance, strictly speaking Hubble's Law is about the relation between the amount of red shift we observe in the light spectrum of a galaxy and the amount of time it took for the light from that galaxy to reach us. If Hubble's Law indicates that it took a particular galaxy 10 billion years to reach us it would NOT be even  approximately correct to say that the galaxy is now 10 billion light years away, it would actually be much much further away than that; and it would also NOT be correct to say that when that light started its journey the Earth was 10 billion light years away, back then it was actually much less than that, or it would've been if Earth had existed 10 billion years ago, which it didn't. 

 Distances to galaxies is measured using standard candles. So the attenuation in brightness compared to intrinsic brightness is a true measure of distance even though the universe is expanding. So there doesn't seem to be any problem with Hubble's values for distances. Or does the attenuation cease to exist due to the expansion of space? TY, AG

You've got to remember Einstein tells us there is a fundamental difference between:

1) Two objects moving through space away from each other. 

2) Space itself between two objects expanding. 

I am aware of these facts. The observed red shift includes both effects and the second effect is much more significant. AG 

In cosmology only the second case is important. If we ignore the era of hyperinflation that ended about 10^-32 seconds after the big bang, for about 9 billion years after the Big Bang space was expanding much faster than it is now, but the rate of expansion was decreasing. About 5 billion years ago things changed, the rate of expansion started to increase,

During inflation, if it existed, the expansion greatly exceeded light speed, and presumably this was when the UNobservable region came into existence. But since there were no galaxies at this time, what exactly couldn't be observed if observers existed to do the observing? TY, AG

If gravity is slowing the rate of expansion, it must have been higher in the past than now. On the other hand, Hubble's law seems to claim that when galaxies are close to each other, the rate of expansion is slow. How do you resolve this contradiction, particularly in the very early universe? TY, AG

[Brent Meeker]

That doesn't follow.  That galaxies(near) are receding more slowly than distant galaxies(distant) now, does not imply they were receding more slowly in the past.  In fact you can invert the argument: assuming they were all together in the past, those receding faster will now be further away.

Brent

[Brent Meeker]

On 12/3/2025 11:05 AM, Alan Grayson wrote:

On Wednesday, December 3, 2025 at 5:51:29 AM UTC-7 John Clark wrote:

On Wed, Dec 3, 2025 at 6:08 AM Alan Grayson <agrays...@gmail.com> wrote:

On Sunday, August 24, 2025 at 10:03:20 PM UTC-6 Alan Grayson wrote:

 

I think not. It just tell us how rapidly it is expanding at different distance, but at the same time, NOW. So, there is no basis for the claim it was expanding very slowly in its very early history. AG

> Wrong conclusion! Since galaxies far away are receding the faster than those close to us, Hubble's law also says that those close to us are receding more slowly than those farther away since in the very early universe the galaxies were closely separated,  Hubble's law says they were receding from each other more slowly than today. AG 

I think you would be less confused if you forget about recessional velocity and forget about distance, strictly speaking Hubble's Law is about the relation between the amount of red shift we observe in the light spectrum of a galaxy and the amount of time it took for the light from that galaxy to reach us. If Hubble's Law indicates that it took a particular galaxy 10 billion years to reach us it would NOT be even  approximately correct to say that the galaxy is now 10 billion light years away, it would actually be much much further away than that; and it would also NOT be correct to say that when that light started its journey the Earth was 10 billion light years away, back then it was actually much less than that, or it would've been if Earth had existed 10 billion years ago, which it didn't. 

 Distances to galaxies is measured using standard candles. So the attenuation in brightness compared to intrinsic brightness is a true measure of distance 

A true measure at what time?

even though the universe is expanding. So there doesn't seem to be any problem with Hubble's values for distances. Or does the attenuation cease to exist due to the expansion of space? TY, AG

You've got to remember Einstein tells us there is a fundamental difference between:

1) Two objects moving through space away from each other. 

2) Space itself between two objects expanding. 

I am aware of these facts. The observed red shift includes both effects and the second effect is much more significant. AG 

In cosmology only the second case is important. If we ignore the era of hyperinflation that ended about 10^-32 seconds after the big bang, for about 9 billion years after the Big Bang space was expanding much faster than it is now, but the rate of expansion was decreasing. About 5 billion years ago things changed, the rate of expansion started to increase,

During inflation, if it existed, the expansion greatly exceeded light speed, and presumably this was when the UNobservable region came into existence. But since there were no galaxies at this time, what exactly couldn't be observed if observers existed to do the observing? TY, AG

If the universe is infinite, as seems likely, most of it was always unobservable, since the observable part is necessarily finite.

If gravity is slowing the rate of expansion, it must have been higher in the past than now. 

Rate of expansion as %/time or as velocity/time?

Brent

On the other hand, Hubble's law seems to claim that when galaxies are close to each other, the rate of expansion is slow. How do you resolve this contradiction, particularly in the very early universe? TY, AG

 

this would make sense IF Dark Energy is an intrinsic part of space because as space expands matter, which wants to retard the expansion gets diluted but space, which wants to increase the expansion, does not. 

However that might not be true, Dark Energy might not be caused by space itself, maybe it's produced by some sort of field that can change with time. Very recently there have been indications that the rate of change of the acceleration of the universe (believe it or not called a cosmic jerk) might be decreasing, but the evidence is not yet strong enough to claim a discovery.   

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

3//

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[Alan Grayson]

On Wednesday, December 3, 2025 at 2:46:22 PM UTC-7 Brent Meeker wrote:

On 12/3/2025 3:08 AM, Alan Grayson wrote:

On Sunday, August 24, 2025 at 10:03:20 PM UTC-6 Alan Grayson wrote:

I think not. It just tell us how rapidly it is expanding at different distance, but at the same time, NOW. So, there is no basis for the claim it was expanding very slowly in its very early history. AG

Wrong conclusion! Since galaxies far away are receding the faster than those close to us, Hubble's law also says that those close to us are receding more slowly than those farther away. So, since in the very early universe the galaxies were closely separated,  Hubble's law says they were receding from each other more slowly than today. AG 

That doesn't follow.  That galaxies(near) are receding more slowly than distant galaxies(distant) now, does not imply they were receding more slowly in the past. 

Yes, I think you nailed my error. Hubble's law just tells us the relative velocities of near and far galaxies, but doesn't imply the galaxies were receding from each other slowly in the very early universe. I'm still puzzled how I could get that implication. AG

 

In fact you can invert the argument: assuming they were all together in the past, those receding faster will now be further away.

What is "inverted" about the argument? AG 

Brent

[Alan Grayson]

On Wednesday, December 3, 2025 at 7:08:03 PM UTC-7 Brent Meeker wrote:

On 12/3/2025 11:05 AM, Alan Grayson wrote:

On Wednesday, December 3, 2025 at 5:51:29 AM UTC-7 John Clark wrote:

On Wed, Dec 3, 2025 at 6:08 AM Alan Grayson <agrays...@gmail.com> wrote:

On Sunday, August 24, 2025 at 10:03:20 PM UTC-6 Alan Grayson wrote:

 

I think not. It just tell us how rapidly it is expanding at different distance, but at the same time, NOW. So, there is no basis for the claim it was expanding very slowly in its very early history. AG

> Wrong conclusion! Since galaxies far away are receding the faster than those close to us, Hubble's law also says that those close to us are receding more slowly than those farther away since in the very early universe the galaxies were closely separated,  Hubble's law says they were receding from each other more slowly than today. AG 

I think you would be less confused if you forget about recessional velocity and forget about distance, strictly speaking Hubble's Law is about the relation between the amount of red shift we observe in the light spectrum of a galaxy and the amount of time it took for the light from that galaxy to reach us. If Hubble's Law indicates that it took a particular galaxy 10 billion years to reach us it would NOT be even  approximately correct to say that the galaxy is now 10 billion light years away, it would actually be much much further away than that; and it would also NOT be correct to say that when that light started its journey the Earth was 10 billion light years away, back then it was actually much less than that, or it would've been if Earth had existed 10 billion years ago, which it didn't. 

 Distances to galaxies is measured using standard candles. So the attenuation in brightness compared to intrinsic brightness is a true measure of distance 

A true measure at what time?

even though the universe is expanding. So there doesn't seem to be any problem with Hubble's values for distances. Or does the attenuation cease to exist due to the expansion of space? TY, AG

You've got to remember Einstein tells us there is a fundamental difference between:

1) Two objects moving through space away from each other. 

2) Space itself between two objects expanding. 

I am aware of these facts. The observed red shift includes both effects and the second effect is much more significant. AG 

In cosmology only the second case is important. If we ignore the era of hyperinflation that ended about 10^-32 seconds after the big bang, for about 9 billion years after the Big Bang space was expanding much faster than it is now, but the rate of expansion was decreasing. About 5 billion years ago things changed, the rate of expansion started to increase,

During inflation, if it existed, the expansion greatly exceeded light speed, and presumably this was when the UNobservable region came into existence. But since there were no galaxies at this time, what exactly couldn't be observed if observers existed to do the observing? TY, AG

If the universe is infinite, as seems likely, most of it was always unobservable, since the observable part is necessarily finite.

I tend to think it's finite in volume, including the unobservable part which was created during the finite doublings of volume during the period of Inflation. It's also likely approximately spherical in shape since that's the usual theme of shapes of material bodies as they get large. For example, smaller material objects like asteroids can be shaped like potatoes, whereas large ones approximate spheres. Galaxies are exemptions to this rule, which of course is not a proof of anything. But one thing seems clear; that measurements can never reveal whether the universe is infinite in volume, that is, flat, since there will always be errors in any measurement, and it's impossible to tell what part of the error, if any, can be attributed to some small curvature, to negate the possibility of a flat or infinite universe. AG 

[John Clark]

On Wed, Dec 3, 2025 at 2:05 PM Alan Grayson <agrays...@gmail.com> wrote:

 > Distances to galaxies is measured using standard candles. So the attenuation in brightness compared to intrinsic brightness is a true measure of distance even though the universe is expanding. So there doesn't seem to be any problem with Hubble's values for distances.

Distance between what, and when? If Hubble gives a figure of 10 billion light years that is the distance the light from a distant galaxy needed to travel through space to reach us, it tells us what the galaxy look like 10 billion years ago, but because space had been expanding while light had been making its journey it is NOT the distance the Earth is from that galaxy now, and is NOT the distance between the two when the light was first emitted.

> If gravity is slowing the rate of expansion, it must have been higher in the past than now. On the other hand, Hubble's law seems to claim that when galaxies are close to each other, the rate of expansion is slow. How do you resolve this contradiction,

You're confusing the amount of expansion and the change in the amount of expansion. Except for the first 10^-32 seconds, until about 5 billion years ago the universe was expanding faster than it is now but the RATE of expansion was negative, things were decelerating. Things changed 5 billion years ago, the RATE of acceleration became positive and the universe started to accelerate. The universe experienced a cosmic jerk. 

> If the universe is infinite, as seems likely, most of it was always unobservable, since the observable part is necessarily finite.

Yes but in the past we could see more of the universe than we can now, and today there are parts of the universe that we can see but we can never affect, if we sent a radio message to it moving at the speed of light it would not arrive there in any finite number of years. 

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

3//

9ii

[Alan Grayson]

On Thursday, December 4, 2025 at 5:39:31 AM UTC-7 John Clark wrote:

On Wed, Dec 3, 2025 at 2:05 PM Alan Grayson <agrays...@gmail.com> wrote:

 > Distances to galaxies is measured using standard candles. So the attenuation in brightness compared to intrinsic brightness is a true measure of distance even though the universe is expanding. So there doesn't seem to be any problem with Hubble's values for distances.

Distance between what, and when? If Hubble gives a figure of 10 billion light years that is the distance the light from a distant galaxy needed to travel through space to reach us, it tells us what the galaxy look like 10 billion years ago, but because space had been expanding while light had been making its journey it is NOT the distance the Earth is from that galaxy now, and is NOT the distance between the two when the light was first emitted.

But when we use standard candles to measure distance from Earth to some galaxy, don't we get the ACTUAL distance NOW, since light attenuates in intensity due to expansion, just as its wavelength increases (and its energy decreases)? AG 

> If gravity is slowing the rate of expansion, it must have been higher in the past than now. On the other hand, Hubble's law seems to claim that when galaxies are close to each other, the rate of expansion is slow. How do you resolve this contradiction,

You're confusing the amount of expansion and the change in the amount of expansion.

I don't think so. See below. One thing that confused me was your claim a few days ago that the expansion rate was slow in the very early universe. I think you were comparing its rate at that time with the rate during Inflation. AG

 

Except for the first 10^-32 seconds, until about 5 billion years ago the universe was expanding faster than it is now but the RATE of expansion was negative, things were decelerating. Things changed 5 billion years ago, the RATE of acceleration became positive and the universe started to accelerate. The universe experienced a cosmic jerk. 

Brent explained my confusion. Hubble's law compares galaxies near and far from us, and states that those far away, are receding the fastest. That FACT does NOT imply that galaxies in the very early universe were receding from each other at a low rate just because they were relatively close to each other at that time. AG 

> If the universe is infinite, as seems likely, most of it was always unobservable, since the observable part is necessarily finite.

Yes but in the past we could see more of the universe than we can now, and today there are parts of the universe that we can see but we can never affect, if we sent a radio message to it moving at the speed of light it would not arrive there in any finite number of years. 

While I agree with your statement, you're responding to Brent's comment which I disagree with it. IMO, the unobservable region came into existence during Inflation, when the universe expanded at a rate hugely greater than light speed. So, it seems plausible that the entire universe, that which arose from a substratum which might be infinite, is finite in spatial extent. AG 

[John Clark]

On Thu, Dec 4, 2025 at 10:09 AM Alan Grayson <agrays...@gmail.com> wrote:

 >>> Distances to galaxies is measured using standard candles. So the attenuation in brightness compared to intrinsic brightness is a true measure of distance even though the universe is expanding. So there doesn't seem to be any problem with Hubble's values for distances.

>> Distance between what, and when? If Hubble gives a figure of 10 billion light years that is the distance the light from a distant galaxy needed to travel through space to reach us, it tells us what the galaxy look like 10 billion years ago, but because space had been expanding while light had been making its journey it is NOT the distance the Earth is from that galaxy now, and is NOT the distance between the two when the light was first emitted.

> But when we use standard candles to measure distance from Earth to some galaxy, don't we get the ACTUAL distance NOW, since light attenuates in intensity due to expansion, just as its wavelength increases (and its energy decreases)? AG 

Cosmology is complicated, and you have to be clear about what sort of distance you're talking about. For example if we look at a galaxy with a red shift of 1 we know that that from our viewpoint the light has been traveling for 7.8 billion years (although from the viewpoint of a photon the travel time was zero) but during that time space has been expanding so if you could somehow pause the expansion of the universe you'd find that the galaxy is now 11 billion light years away from us not 7.8 billion, and when that light was first emitted the galaxy and the Earth were only 5.5 billion light years apart, if the Earth had existed back then.  

And just to make things more complicated, if you used the standard candle method to calculate distance that works fine in a lab you would conclude that the galaxy was 22 billion light years away; but when you're talking about cosmological distances there are two other things you need to take into account: 

1) Photons lose energy as their wavelengths stretch
2) Because of time dilation photons arrive less frequently

These two effects combine to reduce brightness by a factor of (1+z)^2, where z is the redshift.

I think it's interesting that a galaxy with a redshift  of 1.8 is about 16 billion light-years away, but you could never reach a galaxy with a redshift that large or larger. With our largest telescopes we can see galaxies with a red shift of 11, but we could never reach a galaxy with a red shift that big even if you could move at the speed of light because the the space between us is expanding faster than the speed of light,  we can still see it because we are looking at old light, but we could never know what the galaxy looks like now. 

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

9d6

[Alan Grayson]

AG: Here's what Gemini says:

AG: When we use standard candles to measure distances to galaxies, does the result include the expansion of space while the lighting is traveling toward the Earth?

GM; That's an excellent and crucial question in cosmology!

The distance calculated directly from a standard candle's apparent brightness (using the inverse square law of light) does not directly include the effects of space expansion during the light's travel time.

[Brent Meeker]

There are some good online tutorials and calculators to help one get a feeling for the numbers.

https://www.astro.ucla.edu/~wright/cosmo_01.htm

https://www.cosmologycalculator.com/cosmocalc.htm

https://cosmologycalculator.com/D1_preface_documentation.pdf

Brent

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