[Kryptid]

I would like to remind you that if the universe is infinite, then by definition its age must be infinite.

Not so. If the Universe started off with an infinite size, then it would presumably still be infinite in size even if its age is finite. Let's not confuse the total Universe with the observable Universe. The observable Universe can have a finite size while the Universe as a whole can potentially have (and always have had) an infinite size.

[evan_au]

Why the same process (which formed SMBH) can't form less massive black hole seeds?

Physicists are still open to the idea that there may be black holes of many sizes formed in the Big Bang.
- These might have formed when the universe was itself very dense (even denser than quark soup), so it wouldn't have taken so much of a density fluctuation to produce a black hole.
- These would have formed much earlier in the Big Bang timeline than the black holes implied by the Direct Collapse scenario, which operates on neutral atoms

The really tiny black holes won't be around today, because they would have evaporated long ago by Hawking radiation.
- However, ones that started out merely small could still be around today (just a bit smaller)
- Indeed, black holes were an early contender for "Dark Matter", but stellar-mass black holes were ruled out by the low rate of microlensing events
- Micro black holes are still theoretically possible - we just don't have any confirmed sightings (yet)
- Experimental scientists are still actively searching for primordial black holes (which then places limits on how many there might be in the universe today)

https://en.wikipedia.org/wiki/Primordial_black_hole

[evan_au]

A theory is ...like a family tree of COVID-19

There is a significant difference here between scientific theories and COVID-19:
- COVID-19 continually adds new mutations on top of its "parent" virus, resulting in a divergent evolution. Some similar mutations are seen, but they are outnumbered by the dissimilar mutations
- Scientific theories can "cross-breed", taking the best parts of other theories, and mixing in the a particular researcher's theoretical tweaks or experimental results. This will result in a degree of convergence over time which is not seen in COVID-19.

But the overall result may look similar, with one theory slowly taking over, and then being supplanted by an even more successful theory. A high-level graph of this process with COVID-19 is as follows:

COVID_Variant_Frequencies.jpg (73.1 kB . 1624x409 - viewed 1699 times)
See: https://nextstrain.org/ncov/gisaid/global/all-time

[Dave Lev (OP)]

I would like to remind you that if the universe is infinite, then by definition its age must be infinite.

Not so. If the Universe started off with an infinite size, then it would presumably still be infinite in size even if its age is finite. Let's not confuse the total Universe with the observable Universe. The observable Universe can have a finite size while the Universe as a whole can potentially have (and always have had) an infinite size.

Sorry, i'm not sure that I understand this answer.
Based on the BBT the Universe started from "Planck epoch".
https://en.wikipedia.org/wiki/Initial_singularity
The initial singularity is a singularity predicted by some models of the Big Bang theory to have existed before the Big Bang[1] and thought to have contained all the energy and spacetime of the Universe.[2] The instant immediately following the initial singularity is part of the Planck epoch, the earliest period of time in the history of our universe.

https://en.wikipedia.org/wiki/Timeline_of_the_early_universe#Planck_epoch
"Planck epoch
c. 0 seconds (13.799 ± 0.021 Gya): Planck epoch begins: earliest meaningful time. The Big Bang occurs in which ordinary space and time develop out of a primeval state (possibly a virtual particle or false vacuum) described by a quantum theory of gravity or "Theory of Everything". All matter and energy of the entire visible universe is contained in a hot, dense point (gravitational singularity), a billionth the size of a nuclear particle."

So, how that "gravitational singularity, a billionth the size of a nuclear particle" could suddenly be considered as Infinite space without breaking the BBT theory?
We also know that there is no empty space with no energy. Therefore, if the Universe started off with an infinite size then by definition it should have some sort of energy.
How the BBT could work at the same moment on the entire infinite space?
It is stated:
https://en.wikipedia.org/wiki/Big_Bang
"the theory describes an increasingly concentrated cosmos preceded by a singularity in which space and time lose meaning (typically named "the Big Bang singularity")."
If you start the Bang when the Universe is already infinite - then don't you agree that there is a meaning for time and space.
So, how can we claim about concentrated cosmos while this cosmos is already infinite?

Perhaps he should get a chance to explain why he thinks that because we don't know the size and shape of the universe, we can't use this maths

Thanks for giving me the chance

If you start the Big Bang from "Planck epoch", and you claim that the early universe was compact, then by definition due to the expansion rate there is a limit for the maximal size of the Universe.
Please look at the following diagram:
https://lco.global/spacebook/cosmology/early-universe/
Let's assume that the maximal size of the universe after the inflation is X.
We know that the expansion rate is based on Hubble constant  (about 70 (km/s)/Mpc).
Therefore, after 13.8 BY with that kind of expansion rate - there must be a maximal size for the Universe.
If the real universe is bigger than this maximal estimated size, then there must be an error in the BBT.
If you claim that the BBT didn't start from "Planck epoch", then our puzzled scientists should tell us from which size it had started and how the Bang could start while the Universe is already infinite.

The observable Universe can have a finite size while the Universe as a whole can potentially have (and always have had) an infinite size.

That is fully correct.
However, I still don't understand how you get infinite Universe without breaking the starting elements of the BBT.

The really tiny black holes won't be around today, because they would have evaporated long ago by Hawking radiation.

Why do you think that normal BH (with mass bigger 1 M☉) shouldn't evaporate?
In the attached articale they just discuss about BH & micro black holes:
https://en.wikipedia.org/wiki/Hawking_radiation
"Hawking radiation reduces the mass and rotational energy of black holes and is therefore also theorized to cause black hole evaporation"
"The radiation temperature is inversely proportional to the black hole's mass, so micro black holes are predicted to be larger emitters of radiation than larger black holes and should dissipate faster."
https://en.wikipedia.org/wiki/Micro_black_hole
Micro black holes, also called mini black holes or quantum mechanical black holes, are hypothetical tiny (<1 M☉) black holes,

So, the main idea is that any BH should eventually evaporate, however - a tinny BH with  (<1 M☉) should evaporate faster.
Therefore, if that theory is correct, then theoretically, all the BH/SMBH in the universe should be evaporate eventually.

Please be aware that we observe millions of BH/SMBH.
We also clearly observe our MY SMBH.
So far we didn't observe any star that falls in while we see them all ejecting matter from their accretion disc.
We just hope that this matter in the accretion disc is due to stars that fall inwards long time ago.
However, statistically, if that is correct and as we observe millions of BH/SMBH how could it be that we didn't see any sort of fireworks as the star falls in - in any one of those millions over millions SMBH?

Please see the following image of Saggitarius_A:

https://en.wikipedia.org/wiki/Event_Horizon_Telescope#/media/File:EHT_Saggitarius_A_black_hole.tif
This is the first image of Sgr A* extracted from its 2017 observations.
I do recall that few years earlier (2011 or 2012) the mass in the accretion disc was significantly lower.
As we have never observed any falling star into Saggitarius_A, how could it be that the mass in the accretion disc had been increased so dramatically in those few years?
How can you highlight the Hawking radiation while you refuse to accept Hawking message that the mass in accretion disc could come due to Hawking radiation?

Look on all the current observations (and especially on the observation that we didn't see)
We don't see (and would never see) any first generation star.
Please be aware that we observe most-distant-galaxy galaxies with million or billion stars without even one single first generation star.
The estimated age of this galaxy is just 600My.
So, based on the BBT, the first star from the first generation star could only be formed 400 My after the bang. However, we wish to believe that less than 200 M years latter all the first generation had been gone.
Is it real? How can we accept this imagination?


Let's go back to our dear Quasar. It is stated:
https://www.space.com/most-distant-quasar-discovery-giant-black-hole
"In fact, scientists estimate that, on average, this particular quasar's black hole ingests an amount of mass equivalent to 25 suns every year."
Hence,  on average, this particular quasar's black hole ingests an amount of mass equivalent to one sun every two weeks.
We have supper advanced technology.
We can detect stars at the most-distant-galaxy (at a similar distance as this quasar) and even verify their structure.
So, how could it be that after observing that quasar for quite long time, we didn't observe even one tinny star as it falls inwards with amazing fireworks?
As we don't see even one star in the entire universe as it falls inwards (with fireworks) into just one of the Millions of BH/SMBH that we clearly observe, why can't we just assume that the matter in the accretion disc is due to Hawking radiation?
However, in this case, we need to explain how could it me that this quasar is so massive (1.6 B solar mass).
How long we will continue to claim that stars falls in but unfortunately we are just not so lucky enough to see even one falling star (with fireworks)?
If the idea of stars that falls inwards the SMBH was real - don't you agree that we have to observe every day at least one falling star somewhere in the entire Universe?

https://lco.global/spacebook/cosmology/early-universe/
In the following diagram we clearly see that the first star had been formed 400MY after the Bang.
So, I really can't understand why our puzzled scientists claim that the massive SMBH seed could be formed just 100MY after the bang and how it gets its 1.6B Solar mass just 570 MY after the bang while we don't see any star as it falls inwards into that quasar.

Why shouldn't I lock this topic?

You don't have to lock it.
Just tell me to stop the discussion in this topic - and I would stop.

[Bored chemist]

Just tell me to stop the discussion in this topic - and I would stop.

I'd like you to actually start a discussion.
A discussion is where you actually answer the points out to you>
Ones like this

Why shouldn't I lock this topic?

Perhaps he should get a chance to explain why he thinks that because we don't know the size and shape of the universe, we can't use this maths

"the time it has taken for the galaxies to reach their current separations is t=D/v .
But, from Hubble's Law, we know that v=H0D .
So,  t=D/v=D/(H0×D)=1/H0 .
So, you can take 1/H0 as an estimate for the age of the Universe."

which doesn't mention the size and shape of the universe.

I have to say I'm really quite curious about that.

[Bored chemist]

Why do you think that normal BH (with mass bigger 1 M☉) shouldn't evaporate?

We don't think that.
Try not making up silly ideas and ascribing them to us.

[Halc]

Based on the BBT the Universe started from "Planck epoch".

This contradicts the quote you gave which says the Planck epoch is "immediately following the initial singularity". So saying it started with the singularity would be closer. But also, time isn't meaningful until the Planck epoch, so in that way you could admittedly argue that it is the 'start' of the universe.

"All matter and energy of the entire visible universe is contained in a hot, dense point (gravitational singularity), a billionth the size of a nuclear particle."

So, how that "gravitational singularity, a billionth the size of a nuclear particle" could suddenly be considered as Infinite space without breaking the BBT theory?

It doesn't say that. It says the visible universe is that size, not the entire singularity, which, being singular, has no meaningful size/temperature/density/energy/whatever. So what was to become our visible universe was contained in this space under a billionth the size of a particle (which also suggests that a unspecified particle has a size, suggesting a non-fundamental construct of multiple things). Hey, it's wiki, hardly an authoritative source of what represents the current details of the theory.

Therefore, if the Universe started off with an infinite size

It started with the singularity, which means it's singular: It has no meaningful size and other things, which is what they mean by time and space having no meaning. Don't confuse a singularity with a point. The latter has a size. The former is just where physics (certainly classic physics at least, which seems to be the level at which your nonsense is staged) cannot describe the situation.

"the theory describes an increasingly concentrated cosmos preceded by a singularity in which space and time lose meaning (typically named "the Big Bang singularity")."
If you start the Bang when the Universe is already infinite

There you go, giving meaning where it says time and space have no meaning. So no, the universe has no meaningful dimensions at the singularity, but it begins to at the Planck epoch.

So, how can we claim about concentrated cosmos while this cosmos is already infinite?

Learn some grade school mathematics. Concentration (or density actually since concentration seems more of a chemical term) is not measured in meters but rather units of stuff/volume which can be the same for different volumes. Hence knowledge of the size isn't necessary if the density has been measured. For instance, rock (the heavy stuff like you get at say the bottom of the Atlantic) is about 6 times the density of water. Knowledge of the size of the specific rock isn't necessary for that to be known.

If you start the Big Bang from "Planck epoch", and you claim that the early universe was compact, then by definition due to the expansion rate there is a limit for the maximal size of the Universe.

Non-sequitur. By definition of what? Compact? The word as used here just means relativity dense, and as pointed out just above, knowing the density of a thing gives you no clue as to the size of it.

Let's assume that the maximal size of the universe after the inflation is X.

This assumes that it has a finite size, which seems to contradict your typical assertions. The visible universe was perhaps the size of a grapefruit immediately after inflation. Estimates vary considerably.

We know that the expansion rate is based on Hubble constant  (about 70 (km/s)/Mpc).

No, the Hubble constant is based on the current measured expansion rate. It isn't a constant, and it only tells you approximately how old the universe is since it is in units of t^-1.

Therefore, after 13.8 BY with that kind of expansion rate - there must be a maximal size for the Universe.

This absurdly suggests that expansion must stop now since the universe cannot expand further. Do you read your own comments? There is no maximal size, even for a finite size thing, if it continues to expand forever. The visible universe for instance has grown to about 96 BLY across (proper distance along a line of constant cosmological time) and there is no size of it that will not eventually be reached.

If the real universe is bigger than this maximal estimated size, then there must be an error in the BBT.

Or an error in you postulating this maximal size limit. Hmm, which is it you think?

If you claim that the BBT didn't start from "Planck epoch"

The BBT is a theory that started only about a century ago. Perhaps you mean the universe that started from the Planck epoch.

then our puzzled scientists

I'm not locking the topic, but do stop saying that. It is you that is puzzled, apparently by choce. The people whom you are slandering are far more knowledgeable about the theory than any of us and none of them see problems in the places that you do because that's not where the problems are.

So, how could it be that after observing that quasar for quite long time, we didn't observe even one tinny star as it falls inwards with amazing fireworks?

A quasar is about as fireworks as you can get. They consume stellar masses at an insane rate.
Your comments of black holes is very much along the lines of your prior topics, about which you agreed to desist discussion.

Just tell me to stop the discussion in this topic - and I would stop.

But you don't. You're going on again claiming nothing falling into black holes, even the ones that are visibly doing so at the highest rates. So you don't keep your promises to stop.

[Dave Lev (OP)]

You're going on again claiming nothing falling into black holes, even the ones that are visibly doing so at the highest rates

Dear Halc
With your permission...
What do you mean by: "even the ones that are visibly doing so at the highest rates"?
Do you mean that we have many observations for falling stars into SMBHs?

In the following article dated May 12, 2022 it is stated:
https://www.cfa.harvard.edu/news/variable-emission-milky-ways-supermassive-black-hole
"One of the biggest ongoing questions surrounding black holes is exactly how they collect, ingest, or even expel material orbiting them at near light speed, in a process known as “accretion.” This process is fundamental to the formation and growth of planets, stars, and black holes of all sizes, throughout the universe"
It is stated clearly: "One of the biggest ongoing questions surrounding black holes is exactly how they collect, ingest, or even expel material orbiting them".
So, even up to few days ago, our scientists don't really know how the SMBH is exactly collecting material/stars orbiting around them.
However, it is also stated:
"“Astronomers can largely agree on the basics – that black holes have material swirling around them and some of it falls across the event horizon forever,” said Sera Markoff of the University of Amsterdam in the Netherlands,"
So, do you agree that our scientists agree among themselves that some of the material around the SMBH should fall in, however so far they didn't find any real observation to that?
If you think that we have a clear observation for star as it falls into the SMBH and sets severe flare/fireworks during this process - then please offer that observation.

In any case, if you wish to stop the discussion on the idea of falling stars - then we won't discuss about it.
Please let me know if there is any subject in this topic that we shouldn't discuss.

[Kryptid]

So, how that "gravitational singularity, a billionth the size of a nuclear particle" could suddenly be considered as Infinite space without breaking the BBT theory?
We also know that there is no empty space with no energy. Therefore, if the Universe started off with an infinite size then by definition it should have some sort of energy.

That does seem counter-intuitive at first, but a singularity of zero size would have made reference to our observable Universe, not the Universe as a whole. To help you understand, consider looking at it backwards through time. You start off with a universe of infinite size, with roughly the same (low) density everywhere. Our observable Universe is a sphere of limited size within this larger Universe. As you go further back in time, the density of all matter increases and the "bubble" that represents our observable Universe gets smaller. However, the Universe as a whole is still remains infinitely large because no degree of shrinkage can change that. So as you go further and further back in time, our observable Universe continues to shrink until it shrinks to zero (or close to zero) size at the moment of the Big Bang. The total Universe is still infinitely-large at this point, however. It's just that the density everywhere is infinite (or at least very, very high).

[Dave Lev (OP)]

Dear Kryptid
Thanks for the explanation.
However, there is a small problem in this explanation - as follow:

To help you understand, consider looking at it backwards through time. You start off with a universe of infinite size, with roughly the same (low) density everywhere.

Correct.

Our observable Universe is a sphere of limited size within this larger Universe

Still correct.

As you go further back in time, the density of all matter increases and the "bubble" that represents our observable Universe gets smaller.

That is incorrect as the density of matter in our real infinite universe is fixed over time.
However, for our discussion let's assume that your explanation is correct.

However, the Universe as a whole is still remains infinitely large because no degree of shrinkage can change that. So as you go further and further back in time, our observable Universe continues to shrink until it shrinks to zero (or close to zero) size at the moment of the Big Bang.

This could be correct ONLY if you shrink the observable Universe while there is no change in all infinite universe outside that observable universe.
So, how we prove that only the Observable Universe shrinks?
I hope that you agree that the name "observable Universe" is something that we have decided.
Our real universe is significantly bigger. It might be infinite.
Let's agree that there is a Universe that is called Universe M and its radius is 1 Million Times the radius of the Observable Universe. (one million times the 48B LY of the observable Radius).
Now do you think that as we go further and further back in time, the Universe M could shrink to zero (or close to zero) in just 13.8 BY?

The total Universe is still infinitely-large at this point, however. It's just that the density everywhere is infinite (or at least very, very high)

If you can prove that only the Observable Universe shrinks while all the other Universe stay as is then your explanation could be correct.
If not, then as the total Universe is infinitely-large at this point, it would still be infinite even if we shrink it by go back 13.8BY in time.

[Kryptid]

That is incorrect as the density of matter in our real infinite universe is fixed over time.

Not according to the Big Bang theory, it isn't.

This could be correct ONLY if you shrink the observable Universe while there is no change in all infinite universe outside that observable universe.

Not so. All areas of the Universe would shrink more or less equally.

So, how we prove that only the Observable Universe shrinks?

There's no need to.

Now do you think that as we go further and further back in time, the Universe M could shrink to zero (or close to zero) in just 13.8 BY?

Possibly. It depends on the maximum possible density (whether or not that density is infinite). Universe M would have been an awful lot smaller at the Big Bang either way.

If not, then as the total Universe is infinitely-large at this point, it would still be infinite even if we shrink it by go back 13.8BY in time.

That was my entire point. It demonstrates how the Universe as a whole can be infinitely large at the moment of the Big Bang even though our observable Universe was still incredibly tiny.

[Bored chemist]

I'm still waiting for Dave to address this and thereby prove that he is debating not soapboxing.

Just tell me to stop the discussion in this topic - and I would stop.

I'd like you to actually start a discussion.
A discussion is where you actually answer the points out to you>
Ones like this

Why shouldn't I lock this topic?

Perhaps he should get a chance to explain why he thinks that because we don't know the size and shape of the universe, we can't use this maths

"the time it has taken for the galaxies to reach their current separations is t=D/v .
But, from Hubble's Law, we know that v=H0D .
So,  t=D/v=D/(H0×D)=1/H0 .
So, you can take 1/H0 as an estimate for the age of the Universe."

which doesn't mention the size and shape of the universe.

I have to say I'm really quite curious about that.

[Dave Lev (OP)]

It is very clear that the BBT is a theory for the Observable Universe.

The visible universe was perhaps the size of a grapefruit immediately after inflation. Estimates vary considerably.

Hence, based on the BBT - After the inflation it might be in the size of grapefruit.

That was my entire point. It demonstrates how the Universe as a whole can be infinitely large at the moment of the Big Bang even though our observable Universe was still incredibly tiny.

However, now we understand that for infinite universe it must be infinitely large at the moment of the Big Bang.
Therefore, the Big bang should start while the universe is already infinite.
So how can you claim that a theory for a universe that starts as a grapefruit size after the bang and the inflation, could perfectly work while at the big bang moment it is already infinite?
We can claim that the Hubble constant isn't constant at all:

Quote
We know that the expansion rate is based on Hubble constant  (about 70 (km/s)/Mpc).

No, the Hubble constant is based on the current measured expansion rate. It isn't a constant, and it only tells you approximately how old the universe is since it is in units of t-1.

Hence, the value of 70 (km/s)/Mpc is just based on the current measured expansion rate.
So, we can estimate that in the early time it was much bigger.
But how big it could be?
It is very clear that any finite value of that Hubble constant at any given finite time frame (13.8 By or more) can't form an infinite Universe.
I assume that only if we set the Hubble constant as infinite value there is a possibility to get infinite Universe in a finite time.
Therefore, as long as the Hubble constant has a finite value the Big Bang can't create an infinite Universe.
However, if we set ultra high value for the Hubble constant, then the chance to get a massive SMBH seed is zero.
So, there is no way for us to get that 1.6B solar mass in just 670 M years after the bang.
Hence, you have a severe problem in the theory:
1. If the Hubble constant is too low, that grapefruit could end as a SS..SMBH without any Universe
2. If the Hubble constant is not too low or too high you end with a finite universe
3. If the Hubble constant is too high (or infinite), you might get the infinite Universe but not the quasar.

Quote from: Dave Lev on 14/05/2022 14:59:48
"the time it has taken for the galaxies to reach their current separations is t=D/v .
But, from Hubble's Law, we know that v=H0D .
So,  t=D/v=D/(H0×D)=1/H0 .
So, you can take 1/H0 as an estimate for the age of the Universe."

which doesn't mention the size and shape of the universe.

As the Hubble constant isn't constant at all, then this formula which is based only on the current value is just not realistic.
Therefore, even without knowing the size and shape of the universe we clearly know that you can't just use the current Hubble constant in that formula.

[Kryptid]

So how can you claim that a theory for a universe that starts as a grapefruit size after the bang and the inflation, could perfectly work while at the big bang moment it is already infinite?

Because the "grapefruit size" thing only applied to the observable Universe, not the entire Universe. Let's not get those two things confused.

[Bored chemist]

I assume that only if we set the Hubble constant as infinite value there is a possibility to get infinite Universe in a finite time.

You don't "set" it, you measure it.
Making up numbers- particularly infinite ones- is not science.

Also, if you set the Hubble constant to be infinite, the earth would explode infinitely fast.
So we know that idea is wrong- even if it wasn't anti-science.
Setting that aside, you still haven't answered my point
It's as if you miss the point deliberately.
If the age of the universe is (about) 1/ H then obviously H changes- because the age of the universe changes.

It's as stupid as saying you can't count the rings in a tree to determine the age- because the number of rings changes. It will only tell you the current age of the tree.
Well. yes, of course it will.
But the current age is exactly the thing we want to determine.

And that's all beside the point.

The size and shape of the universe do not occur in this equation.

"the time it has taken for the galaxies to reach their current separations is t=D/v .
But, from Hubble's Law, we know that v=H0D .
So,  t=D/v=D/(H0×D)=1/H0 .
So, you can take 1/H0 as an estimate for the age of the Universe."

So any change to the size and shape of the universe would not affect that equation.
So we do not need to know what the size and shape of the universe are, in order to calculate that equation.


So why do you say we can't?

[Dave Lev (OP)]

You don't "set" it, you measure it.

Yes, we can measure the Hubble constant.
and it is constant everywhere.
https://www.researchgate.net/figure/The-Hubble-diagram-or-the-velocity-distance-relation-plot-for-type-Ia-supernovae_fig1_331983227
The Hubble diagram or the velocity-distance relation plot for type Ia supernovae
The velocity-distance relation plots for freely expanding gas molecules (Figure 2 to Figure 6) are exactly like the velocity-distance relation plot for the receding large-scale structures according to the Hubble diagram; the molecules receding slowly are closer to us whereas the molecules receding faster are further away from us.
Hence, at any distance and at any direction from us the Hubble constant is always 70 (km/s)/Mpc.
However, our universe must be symmetrical.
Therefore, the value of Hubble constant should exists at any location in the entire infinite universe.
Hence, if we could jump to a point that is located at 10BLY from us we would find that any galaxy that is located in the visible universe of that point has exactly the same Hubble constant.
That is also correct to a point that is located at 100BLY away, 1 Trillion years away and even in the infinity LY away.

Making up numbers- particularly infinite ones- is not science.

I hope that you don't have intention for making up numbers by claiming that suddenly after our observable universe radius, that Hubble constant value is different.

The size and shape of the universe do not occur in this equation.

Quote from: Dave Lev on Yesterday at 17:43:02
"the time it has taken for the galaxies to reach their current separations is t=D/v .
But, from Hubble's Law, we know that v=H0D .
So,  t=D/v=D/(H0×D)=1/H0 .
So, you can take 1/H0 as an estimate for the age of the Universe."

So any change to the size and shape of the universe would not affect that equation.
So we do not need to know what the size and shape of the universe are, in order to calculate that equation.

You are absolutely correct!
As the Hubble constant is constant at any location in the entire infinite Universe.
Therefore, let's read again the message from Kryptid:

As you go further back in time, the density of all matter increases and the "bubble" that represents our observable Universe gets smaller.

Sorry, that message is correct not just for our observable Universe but for the entire infinite Universe as the Hubble constant should be equal everywhere in the entire universe.
Hence, As you go further back in time, the density of all matter increases and the "bubble" that represents our observable the entire infinite Universe gets smaller.
Therefore, as 1/H0 is the calculated age of the Universe, then the age of the entire infinite Universe is 13.8 BY.
Hence, 13.8 BY ago, just after the Big Bang and the inflation the size of the entire infinite Universe was at the size of "grapefruit".
Therefore, as long as we all agree that the Hubble constant is equal everywhere - the Big bang should create our current infinite universe from a single bang.
There is no other option!
The only question is: Do you accept that option as a realistic option for the BBT?
Is it possible for the Big Bang to form Infinite Universe in a single bang that took place 13.8 By ago?
Please remember the following message:

Making up numbers- particularly infinite ones- is not science.

So please don't make up numbers- particularly not Hubble constant at the infinity just to fit it into the BBT theory.

Why is it so difficult for all of you to look for better explanation that can explain how the Hubble constant could be equal everywhere in the entire infinite universe without breaking any science law?

[Bored chemist]

OK, lest stop being silly.
You are still trying to say that we can't use this

"the time it has taken for the galaxies to reach their current separations is t=D/v .
But, from Hubble's Law, we know that v=H0D .
So,  t=D/v=D/(H0×D)=1/H0 .
So, you can take 1/H0 as an estimate for the age of the Universe."

because we don't know the size of the universe.
Lets try a few different sizes for the universe and see what difference it makes.
The Universe is small enough to fit in my pocket say 0.01 metres

1/H0 is about 14 billion years.

Now let's say the universe is a trillion light years across
1/H0 is still about 14 billion years.


Did you notice that 1/ H0 does not actually change?

[Bored chemist]

So please don't make up numbers- particularly not Hubble constant

I didn't make it up- I copied the value that was measured by actual scientists.

just to fit it into the BBT theory.

Technically, there's quite a big range of values that would more or less work.

You are the one cherry picking a value to make it look like your idea works.
You chose one  of the values it can't have- infinity.
If the speed of expansion was infinity times the distance away then my monitor which is about a metre away would be receding at a rate of 1 times infinity ie infinity metres per second.
Well that's plainly wrong.

[Dave Lev (OP)]

OK, lest stop being silly.
You are still trying to say that we can't use this

"the time it has taken for the galaxies to reach their current separations is t=D/v .
But, from Hubble's Law, we know that v=H0D .
So,  t=D/v=D/(H0×D)=1/H0 .
So, you can take 1/H0 as an estimate for the age of the Universe."

because we don't know the size of the universe.
Lets try a few different sizes for the universe and see what difference it makes.
The Universe is small enough to fit in my pocket say 0.01 metres

1/H0 is about 14 billion years.

Now let's say the universe is a trillion light years across
1/H0 is still about 14 billion years.


Did you notice that 1/ H0 does not actually change?

I say again that you are fully correct.

1/H0 is about 14 billion years.
Now let's say the universe is a trillion light years across
1/H0 is still about 14 billion years.

Fully agree!
Even if the size of the Universe is Billion over trillion LY across or infinite, 1/H0 is still about 14 billion years.
So please explain how a single bang that took place 13.8BY ago could set a trillion light years or infinite Universe?

[Dave Lev (OP)]

Quote from: Dave Lev on Today at 17:35:46
just to fit it into the BBT theory.

Technically, there's quite a big range of values that would more or less work.

Please elaborate

If the speed of expansion was infinity times the distance away then my monitor which is about a metre away would be receding at a rate of 1 times infinity ie infinity metres per second.
Well that's plainly wrong.

Do you claim that the BBT cant form an infinite Universe?

You chose one  of the values it can't have- infinity.

So what is the real size of the entire Universe?
Prove it please.