Number of Galaxies: Is It Infinite?

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SUMMARY

The discussion centers on the question of whether the number of galaxies in the universe is infinite. Participants argue that if there were an infinite number of galaxies, it would imply an infinite number of Earth-like planets and other absurdities, which they deem impossible. Michael Turner, a prominent cosmologist, suggests that the emerging "new cosmology" model indicates spatial flatness, which could imply an infinite universe. However, some participants challenge the concept of infinity, asserting that it is a human construct and does not exist in reality.

PREREQUISITES
  • Understanding of General Relativity and its implications for cosmology
  • Familiarity with the concept of spatial flatness in cosmological models
  • Knowledge of observational cosmology and its evolution over the past decade
  • Awareness of the debates surrounding the Big Bang theory and alternative cosmological models
NEXT STEPS
  • Research Michael Turner's contributions to cosmology and the "new cosmology" model
  • Study the implications of spatial flatness in General Relativity
  • Explore alternative cosmological models, such as plasma cosmology
  • Investigate the criticisms of the Big Bang theory and the arguments for a finite universe
USEFUL FOR

Astronomers, cosmologists, and anyone interested in the philosophical implications of infinity in the context of the universe's structure and origins.

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There's contantly discussion about if the universe is infinite in size or not. I want to pose the question in another way: Is the number of galaxies infinite? My answer: No
 
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well of course because infinity is not a number

... but what is YOUR reasoning?
 
Well, my (dodgy) reasoning is that, if there exist an infinite number of galaxies, must exist infinity Earth planets, and then must exist an infinite number of presidents Bush. This can't be possible!

Seriously, I don't have a well elaborate reasoning. I don't know if is even possible to know it. Just checking the opinion of the other members
 
Originally posted by meteor
Well, my (dodgy) reasoning is that, if there exist an infinite number of galaxies, must exist infinity Earth planets, and then must exist an infinite number of presidents Bush. This can't be possible!


That is quite excellent reasoning! I can't see how the Universe could allow such an absurdity!



{{{though I do believe in a Universe of infinite extension}}}
 
Originally posted by meteor
Well, my (dodgy) reasoning is that, if there exist an infinite number of galaxies, must exist infinity Earth planets, and then must exist an infinite number of presidents Bush. This can't be possible!

Seriously, I don't have a well elaborate reasoning. I don't know if is even possible to know it. Just checking the opinion of the other members

there is a some part of the discussion which involves mere opinion
and speculation

but there is a parallel discussion that involves models
and involves facts

here is an example. Michael Turner is one of the world's top cosmologists (UChicago, Fermilab Astrophysics Center) and last
year he published a non-technical overview of the rapid change going on in cosmology. the field is radically different from 10 years ago. it's becoming an observational science. the basic numbers and models are stabilizing.

arxiv:astro-ph/0202008

a standard model of the universe is emerging and he describes it.
one feature of the standard model, which he calls the "new cosmology", is spatial flatness. Assuming the underlying mathematical model is General Relativity, this means infinite space.

And an infinite amount of energy spread out in that space. One may assume the energy out beyond the horizon is like what we see----that is some 4 percent of it is visible and collected into galaxies. So an infinite number of galaxies. It is plausible to assume that things beyond the horizon look pretty much like
what we can see. Roughly the same types of galaxies and stars, the same microwave background, and so on. But since we can't see we can't say for sure.

Spatial flatness, implying infinite extent among other things, is in the process of being checked with increasing precision.

People sometimes get the notion that the "singularity" at time zero occurred at a "single point"
but the model does not say this
I think people get this idea because "singularity" sounds like "single". But the singularity (which means a divergence in the GR geometry) occurs over an infinite spatial extent. A singularity in a physical model is usually something to resolve---a gap or flaw in the model. Quantizing GR will probably do away with the famous time-zero singularity and replace it with a continuity at time-zero.
The continuity will be spatially infinite in extent just as now the singularity is spatially infinite.

Some progress has been made already:

Ashtekar "Quantum Geometry in Action: Big Bang and Black Holes"
arxiv:math-ph/0202008
 
I think the question you should be asking is what is the
distrubution of the universe. If one assumes the extent of the universe is infinite, and that galaxies are relatively uniformly distrubuted, then it must be safe to assume the number of galaxies infinite (in so far as it makes sense to talk about infinite numbers of objects)
 
Originally posted by marcus

a standard model of the universe is emerging and he describes it.
one feature of the standard model, which he calls the "new cosmology", is spatial flatness. Assuming the underlying mathematical model is General Relativity, this means infinite space.

Fascinating. Is this "new cosmology" at all related to the plasma cosmology models which do suggest much more coherent explanations of the astronomical and planetary data and also suggest a "spatial flatness" and a universe of infinite duration and extent?

for example see www.electric-cosmos.org

How does a universe of infinite extent fit in with a Big Bungle cosmology?
 
In reality there is no such thing as infinite. Infinite is just something man created, but it doesn't exist in reality - in any form at all.

Futhermore you can't have the big bang and have an infinite universe. The big bang can only create a finite expanding universe.
 
Originally posted by CrystalStudios
In reality there is no such thing as infinite. Infinite is just something man created, but it doesn't exist in reality - in any form at all.

Futhermore you can't have the big bang and have an infinite universe. The big bang can only create a finite expanding universe.


In reality we don't know if the universe is infinite in extent or not. And the big bang is a modern creation myth.
 
  • #10
Originally posted by subtillioN
In reality we don't know if the universe is infinite in extent or not. And the big bang is a modern creation myth.


MYTH? Now how absurd do you sound.

The big bang has been proven in more than 100 independent results. If you think that's a myth then tell me.

EVerytime you sit down in a chair do you fear falling right through the chair?? I didn't think so.
 
  • #11
Originally posted by CrystalStudios
MYTH? Now how absurd do you sound.

The big bang has been proven in more than 100 independent results. If you think that's a myth then tell me.

EVerytime you sit down in a chair do you fear falling right through the chair?? I didn't think so.

How dogmatic do you sound? and what does gravity have to do with proving the big bang?

There is much data ignored by the mainstream that shows that it is incorrect. Ever heard of Halton Arp? He showed that the doppler interpretation of the red-shift is erroneous. Also it is well known that Planck radiation of every atom in the ubiquitous interstellar medium can and should emit a ambient radiation temperature of about 3K. see http://www.Newtonphysics.on.ca/COSMIC/Cosmic.html

see www.electric-cosmos.org for more information
 
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  • #12
Originally posted by subtillioN
How dogmatic do you sound? and what does gravity have to do with proving the big bang?

There is much data ignored by the mainstream that shows that it is incorrect. Ever heard of Halton Arp? He showed that the doppler interpretation of the red-shift is erroneous. Also it is well known that Planck radiation of every atom in the ubiquitous interstellar medium can and should emit a ambient radiation temperature of about 3K. see http://www.Newtonphysics.on.ca/COSMIC/Cosmic.html

see www.electric-cosmos.org for more information


haha - this guy thinks the BB is a myth

Everyone laugh at him hahahaha!
 
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  • #13
Originally posted by CrystalStudios
haha - this guy thinks the BB is a myth

Everyone laugh at him hahahaha!

Excellent argument! Everybody heckle the non-believer!
[zz)]

A desperate appeal to the mob mentality.
 
  • #14
Originally posted by subtillioN
Excellent argument! Everybody heckle the non-believer!
[zz)]

A desperate appeal to the mob mentality.


Yeah well - come on now - your claim is so absurd it isn't worth debating! It's worse than creationism!
 
  • #15
Originally posted by CrystalStudios
Yeah well - come on now - your claim is so absurd it isn't worth debating! It's worse than creationism!

That is a cop-out. If you think it is absurd then explain WHY you think it is such. Otherwise your claim is empty and simply reveals your ignorance of my position.
 
  • #16
There's even another possibility

that you don't see mentioned very often. That the Universe is finite and has a boundary, and is always expanding at the boundary. It is not homogenous or isotropic, unless you are located at the "center", where you would have trouble telling it from the standard "Big Bang" universe because it would appear nearly homogenous and isotropic. As space expands away from the boundary it flattens and becomes uniform.
 
  • #17
well of course because infinity is not a number

Incorrect. It is certainly possible to correctly answer "yes" to queries of the class; "Is the number of X finite?"



How does a universe of infinite extent fit in with a Big Bungle cosmology?

I'm unfamiliar with Big Bungle cosmology, so I can't answer this question.


He showed that the doppler interpretation of the red-shift is erroneous.

Okay. What about gravitational redshift? And you do realize that expanding space would redshift waves passing through it, right?


Also it is well known that Planck radiation of every atom in the ubiquitous interstellar medium can and should emit a ambient radiation temperature of about 3K. see http://www.Newtonphysics.on.ca/COSMIC/ Cosmic.html

It certainly isn't well known to me. I'm not inclined to accept that link as a reputable source due to its absurd treatment on Olber's paradox. If you opt to defend their article, consider also a more serious paradox related to Olber's paradox; we should be observing an infinite amount of EM energy if the universe was infinite and homogenous.
 
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  • #18
Hukyl - You are fine on all points except one.

Infinite is NOT a number.

There is no such thing as an infinite amount of anything. It does not exist in reality.
 
  • #19
http://mathworld.wolfram.com/CardinalNumber.html

The cardinal numbers are a superset of the natural numbers, and are the proper number system in which to express the size of a set. (a.k.a. how many of something there is) The cardinal numbers can be divided into two classes; the natural numbers (a.k.a. finite) and the rest (a.k.a. infinite). I'll admit to being a little harsh and nitpicky, but that decision was directly influenced by the attitude of the one to whom I was responding!


You may well be right that reality is discrete (otherwise, at the very least, there would be an infinite number of points in the universe), but we certainly don't know for sure.
 
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  • #20
Infinite can be used in math just fine. But it doesn't exist in reality.

Reality math is perfection - and stands above science (which adheres to linguistics).

However all of math is not reality.

For instance the old trickery of continuously steping 1/2 the distance towards an object, mathematically you will never reach it.

That expression stands outside the math of reality.

I reject the claim that infinite as a value of anything exists in reality.
 
  • #21
For instance the old trickery of continuously steping 1/2 the distance towards an object, mathematically you will never reach it.

If stepping half of the way took one unit of time each time, you would be correct. However, I tend to cover 1 meter in half the time it takes me to cover 2 meters!

If I'm running at 1 meter per second and I want to cover a distance of 16 meters, the "old trickery" only tells me that I can't make it all the way to 16 meters in less than 16 seconds!
 
  • #22
Originally posted by Hurkyl
If stepping half of the way took one unit of time each time, you would be correct. However, I tend to cover 1 meter in half the time it takes me to cover 2 meters!

If I'm running at 1 meter per second and I want to cover a distance of 16 meters, the "old trickery" only tells me that I can't make it all the way to 16 meters in less than 16 seconds!


Apparently you have no clue what I said.

THe mathematics I used have nothing to do with time at all whatsoever.
 
  • #23
THe mathematics I used have nothing to do with time at all whatsoever.

I think they do; it just was not explicit!


In any case, tell me how you would go about mathematically proving:

For instance the old trickery of continuously steping 1/2 the distance towards an object, mathematically you will never reach it.
 
  • #24
X is the distance you are from the point you are trying to reach, in the beginning. The function shows your distance as you take steps such that each step cuts your distance from the point before the step, in half.

Here is the function that proves it:

X(Y) = (.5 to the power of Y) times (X)

So, if one was to reach the point you are originally a distance of X from - then one would need to find a value for Y in the function that results in:

X(Y) = 0


And there is none. Thus if you continuously take steps that "half" your distance to a certain point, you can never reach it.

Furthermore - The function is conjoured just now - so if I am mistaken it is a fault of my function. The logic still stands.
 
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  • #25
Okay. What about gravitational redshift? And you do realize that expanding space would redshift waves passing through it, right?

Wrong. The expansion of space would be imperceptible because we are embedded in space. The whole premise is ludicrous.


It certainly isn't well known to me. I'm not inclined to accept that link as a reputable source due to its absurd treatment on Olber's paradox. If you opt to defend their article, consider also a more serious paradox related to Olber's paradox; we should be observing an infinite amount of EM energy if the universe was infinite and homogenous.

So, in other words you have no argument against it? It gives a simple explanation of the MBR and you cannot dispute it so you find something that you don't agree with and simply call it absurd.

Olber's Paradox does not take into account the fact that there is much intersteller gas and dust to absorb and re-emit the radiation as 3K heat. Quite simple really.
 
  • #26
Wrong. The expansion of space would be imperceptible because we are embedded in space. The whole premise is ludicrous.

It would manifest itself as a tendency for things to expand. Things like solar systems or atoms are self-correcting so their actual sizes would not increase as the universe expands (in a classical picture, it would manifest as a slight force), but something like an intergalactic light wave or cosmic microwave background radiation is not self-correcting, and the expansion of the wave causes redshifting.


So, in other words you have no argument against it? It gives a simple explanation of the MBR and you cannot dispute it so you find something that you don't agree with and simply call it absurd.

Correct, at that moment I had no argument against it. I had not yet attempted to formulate one. I brought up Olber's paradox because it was so blatant.


Olber's Paradox does not take into account the fact that there is much intersteller gas and dust to absord and re-emit the radiation as 3K heat. Quite simple really.

Yes; which is why it's astonishing that the link you gave didn't bring that up.

It is curious why it's 3K nearly everywhere, instead of having a temperature gradient where gas steadily cools as it gets further and further away from galaxies. It's curious enough that in my mind it's a serious flaw in the model.


But as I mentioned, there's a more serious version of Olber's paradox which this explanation does not solve. The energy received from a star drops off as the square of the distance from the star... but the number of stars at a particular distance increases as the square of distance. Add up all of the energy received from all of the stars, and you predict that we should be observing an infinite amount of energy, if the unvierse was eternal, infinite, and homogeneous.
 
  • #27
Thus if you continuously take steps that "half" your distance to a certain point, you can never reach it.

But it wasn't a complete depiction of my motion anyways. Your reasoning is only valid when my distance from my goal is in the interval (0, X]; not when it's in the interval [0, X]. Your argument only tells me that over the period of my motion where my distance is (0, X], I cannot have reached my goal.
 
  • #28
Originally posted by Hurkyl
It would manifest itself as a tendency for things to expand. Things like solar systems or atoms are self-correcting so their actual sizes would not increase as the universe expands (in a classical picture, it would manifest as a slight force), but something like an intergalactic light wave or cosmic microwave background radiation is not self-correcting, and the expansion of the wave causes redshifting.


On one hand BBT says to ignore the relative motions of galaxies at the edges of the visible Universe moving through space near light speed according to the doppler interpretation of red-shift. It says that these speeds do not violate relativity because it is only space itself that is expanding. On the other hand it can say that the expansion of space can cause physical relativistic effects within space seen in the red-shift. So which is it? Is the expansion of space exempt from the laws of physics within it or is it not?




Yes; which is why it's astonishing that the link you gave didn't bring that up.

Did you read the article? What I said about the paradox is pretty much what it says as well.

It is curious why it's 3K nearly everywhere, instead of having a temperature gradient where gas steadily cools as it gets further and further away from galaxies. It's curious enough that in my mind it's a serious flaw in the model.

The gas is EVERYWHERE and there are galaxies in every line of sight.
 
  • #29
Did you read the article? What I said about the paradox is pretty much what it says as well.

Yes I did, and I just re-read it. The article does not say that interstellar gas is blotting out the light from the infinite number of stars.



On one hand BBT says to ignore the relative motions of galaxies at the edges of the visible Universe moving through space near light speed according to the doppler interpretation of red-shift. It says that these speeds do not violate relativity because it is only space itself that is expanding. On the other hand it can say that the expansion of space can cause physical relativistic effects within space seen in the red-shift. So which is it? Is the expansion of space exempt from the laws of physics within it or is it not?

This is fairly confusing...

General Relativity says that variations in space-time can change the frequency of a photon passing through it.

Inflationary models predict that the majority of space has a quality that will result in the redshifting of light.

Why would near light speeds violate relativity anyways?

According to General Relativity, the expansion of space (and all of the other dynamics of space-time) is governed by Einstein's field equations.


The gas is EVERYWHERE and there are galaxies in every line of sight.

So? That's no reason why there shouldn't be temperature differentials.
 
  • #30
Originally posted by Hurkyl
Yes I did, and I just re-read it. The article does not say that interstellar gas is blotting out the light from the infinite number of stars.


No it says that the radiation is absorbed and re-emited as 3K heat.


This is fairly confusing...

The confusion is inherent in the absurdity of BBT.

So? That's no reason why there shouldn't be temperature differentials.

The reason is that the matter emits Planck radiation at a specific frequency. Read the article. It tells you that.
 

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