Poll: Is the universe finite?

  • Thread starter marcus
  • Start date

Do astronomers think the universe is finite, like an expanding 3D balloon?

  • Yes, there is general agreement among the experts that it's like that

    Votes: 2 25.0%
  • No, there's a general consensus that it's flat and infinite

    Votes: 3 37.5%
  • It's controversial---the experts disagree

    Votes: 3 37.5%

  • Total voters
    8
  • Poll closed .

marcus

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Is the universe finite?

Was the big bang located at a single point and did it involve a finite amount of energy?
Is space like the surface of a balloon (except 3D instead of 2D)
that is gradually expanding?
Does it have positive curvature so that if you continue along a straight line you might get back to the same place?
Are cosmologists at odds about the finiteness vs. infiniteness of the universe or has a consensus developed based on reliable observations?
I want to know what PF posters think so I'll try to construct a poll---this is my first attempt at a poll.
 
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Re: Is the universe finite?

Originally posted by marcus
Was the big bang located at a single point and did it involve a finite amount of energy?
Is space like the surface of a balloon (except 3D instead of 2D)
that is gradually expanding?
Does it have positive curvature so that if you continue along a straight line you might get back to the same place?
Are cosmologists at odds about the finiteness vs. infiniteness of the universe or has a consensus developed based on reliable observations?
I want to know what PF posters think so I'll try to construct a poll---this is my first attempt at a poll.
The only thing that scientists largely agree on is that space has no boundaries or edges. It is called the no boundary proposal (Stephen Hawking).

Our measurements of space indicate it is perfectly flat, which means that it is very large indeed. We can not distinguish between an infinite space and a very large space in observations.

The Big Bang supposedly was not a single point in space, but all of space was expanding.
 
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Eh

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The no boundary proposal is something entirely different.

But the question of infinite can never be confirmed by any experimental evidence. But if nature holds no other infinites, I would wager space is finite.
 

russ_watters

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The way the poll is worded, its a factual question, not an opinion. The vast majority of experts DO in fact agree that the universe is boundless, yet is epanding and is therefore finite. Thats a fundamental aspect of the Big Bang theory.
 

Eh

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Those same experts will tell you expansion does not necessarily equal a finite universe.
 

russ_watters

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Originally posted by Eh
Those same experts will tell you expansion does not necessarily equal a finite universe.
If it started small with a Big Bang Singularity, it must have been finite when it began. So does that mean at some point in time it went from finite to infinite? That makes no sense.
 

marcus

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Originally posted by russ_watters
If it started small with a Big Bang Singularity, it must have been finite when it began. So does that mean at some point in time it went from finite to infinite? That makes no sense.
Nobody claims the big bang singularity was pointlike
on the contrary
here is a cosmology FAQ about that

http://www.astro.ucla.edu/~wright/infpoint.html

QUESTION "How can the Universe be infinite if it was all concentrated into a point at the Big Bang?"


The answer begins: "The Universe was not concentrated into a point at the time of the Big Bang. But the observable Universe was concentrated into a point...."

Then it shows a picture of the big bang (a finite section of an infinitely extending big bang).

The part of the universe from which light has already reached us, the observable universe which is around 80 billion LY diameter at present, WAS concentrated a single point------like in the picture---but that is only a finite piece of an infinite universe

Here is an alternative link to the Michael Turner survey article
on new (post 1998) cosmology:

http://www.lp01.infn.it/proceedings/turner.pdf [Broken]

I posted a link to this article in the Los Alamos archive earlier
but now that does not seem to work. Fortunately the alternative
does, at least for the moment. This article is invaluable because
authoritative and up to date (as of spring 2002).
 
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damgo

AFAIK, there are really only two possibilites now: a flat, infinite universe -- this is the preferred view -- or a flat finite universe with nontrivial topology. ie, the universe 'wraps around' spatially like a game of Asteroids. I am told there are problems with inflation in a finite universe, but there are sky searches and stuff underway to look for evidence of it (ie a hall of mirrors effect.) see

http://arxiv.org/abs/astro-ph/9802012
http://arxiv.org/abs/gr-qc/0005128
http://arxiv.org/abs/gr-qc/9911049
 

marcus

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Originally posted by damgo
AFAIK, there are really only two possibilites now: a flat, infinite universe -- this is the preferred view -- or a flat finite universe with nontrivial topology. ie, the universe 'wraps around' spatially like a game of Asteroids. I am told there are problems with inflation in a finite universe, but there are sky searches and stuff underway to look for evidence of it (ie a hall of mirrors effect.) see

http://arxiv.org/abs/astro-ph/9802012
http://arxiv.org/abs/gr-qc/0005128
http://arxiv.org/abs/gr-qc/9911049
In effect, a "Donut" universe---a zerocurvature cylinder with ends identified.
I have seen mention of sky searches for repetition of that sort
but I also get the strong impression that "hall of mirrors" donut is viewed as only a marginal possibility and that preference is predominantly for flat infinite.
 
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Finite Universe?

Well this is a serious question. The only problem is that you will probably never get anyone to tell you the Truth. Astronomers, Physicists, nor Mathematicians, actually understand Nature. In other words, at best, all knowledge is a Guess of varying Degrees ... No one knows the Absolute Truth, or anything reliable about Mathematics or the Mathematical Sciences. In which case, with all their Billions spent on Research, if they get anything correct ... Well. Do you believe in Luck? Because, for a fact, the correctness of any subject being taught is a Probability Measurement.

Now, consider what would be the effects upon the expanding Universe Theory if the Motion of every Object followed an Orbital Path? I mean, just think, in a case such as this, every Object would appear, relative to their Orbital Paths, either moving away or towards Earth ... Thus, rendering the same visual effects as described in the Big Bang Theory.

e. terrell
 
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No, the universe is not finite. It is infinite. There is no end to it. If there were, where woudl it be? Would you be notified with a sign that says, "The Universe ends here"? It's silly to say the universe is finite. It makes no sense.
 
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I personally think there should be 100 % of the votes in "controversial". The others implies that you are biased on something that has not been proven. That's not a really good stand to take. I would like to say it is infinite, but until it turns from a theory to a law, it's controversial.

Then again, in theory, aren't all laws theories? :smile: jk

Paden Roder
 
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Actually, you are right. All laws are theories. Nothing is proven to be right and never will be.
 
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I guess its controversial – the experts disagree.

How can space extend out forever? I don’t think it can. So what is the geometry of space if its not infinite?
 
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marcus said:
Was the big bang located at a single point and did it involve a finite amount of energy?
Is space like the surface of a balloon (except 3D instead of 2D)
that is gradually expanding?
Does it have positive curvature so that if you continue along a straight line you might get back to the same place?
Are cosmologists at odds about the finiteness vs. infiniteness of the universe or has a consensus developed based on reliable observations?
I want to know what PF posters think so I'll try to construct a poll---this is my first attempt at a poll.
Q. Was the big bang located at a single point and did it involve a finite amount of energy?

A. Yes.

Q. Is space like the surface of a balloon (except 3D instead of 2D)
that is gradually expanding?

A. Yes and No. The universe is like a balloon (finite). But, only a subset of this volume contains all normal matter.

Q. Does it have positive curvature so that if you continue along a straight line you might get back to the same place?

A. Yes

Q. Are cosmologists at odds about the finiteness vs. infiniteness of the universe or has a consensus developed based on reliable observations?

A. Finite - minority
infinite - majority

I think the majority favor an infinite universe only because a reasonable alternative has not been presented to date that would indicate otherwise.

Until we have a better understanding of dark energy and dark matter, we will not be able to explore some options that should come to light explaining how contraction would be possible when considering the present rate of expansion.
 

Chronos

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marcus said:
Was the big bang located at a single point and did it involve a finite amount of energy?
No, it happened everwhere. The total energy involved may, however, been huge thought finite (opinion).
marcus said:
Is space like the surface of a balloon (except 3D instead of 2D) that is gradually expanding?
Possibly. But, I think the answer is a bit more complicated than that.
marcus said:
Does it have positive curvature so that if you continue along a straight line you might get back to the same place?
It probably has some curvature, albeit might be local. No, you cannot travel back to the same place. You would spiral outwards with expansion.
marcus said:
Are cosmologists at odds about the finiteness vs. infiniteness of the universe or has a consensus developed based on reliable observations?
marcus said:
Since when did cosmologists not argue?
marcus said:
I want to know what PF posters think so I'll try to construct a poll---this is my first attempt at a poll.
Since when did cosmologists not argue?
 
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The notion of an infinite universe leads to obsurdities - particularly if its homogenous - there would be an infinite number of identical solar systems, with identical earths and human populations - even an infinite number of Yogi(s). All things of finite probabability are repeated an infinite number of times (plentitude with a vengence). We would be the victims of a gigantic cosmic hoax - each of us falsely believing we are unique.
 
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Maybe these types of issues arise because somewhere along the way, theorists have slipped into digital thinking - as James Jeans once said: you can prove almost anything is you fail to consider the law of the excluded mean. The big bang may not have been a singular event - as Eddington said.."the most satisfactory theory would be one that made the beginning not too unasthetically abrupt. Perhaps inflation is not a phenomena that had a beginning and an end, but rather it is an ongoing process in a negative pressure environment that creates mass as it expands (an idea once posed by its originator). These models do not require a critical density universe to be infinite - ergo the choice between the finite and infinite is dissolves because there is no rational mathematical model for the latter.
 
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well, a theory not too old.. have said that the universe is finite and has the shape of a dodecaedron (12 pentagons in a round shape). and whenever the light comes in from a certain pentagon, it gets out from the opposite one giving illusions for other pentagons and dodecaedrons..
but my question is: if that universe if finite and it is completly inside this dodecaedron.. then from where comes the light which gives different illusions.. which make us think that our universe is infinite?
 
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The universe is a creation out of the state of eternity. Eternity is a condition without time. All is now. The creation was a dimensional energy differential. The universe will continue to expand and exist until all energy differentials drop below the Planck level at which time no actions can take place. In effect all clocks stop ticking. Thus the universe is finite.
 
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I would say the universe is finite. Firstly, the big bang has it that total mass & energy of the universe started from a point of volume zero. A huge gravitational force might be holding all the galaxies together in an oval shape (IMO). Secondly, the proof that the universe is expanding means that it has its limits. Can something expand while its infinite?? I don't guess so.
 
i tend to think that the universe is infinite, and could be one of infinite other universes, in affect one huge 'infiniverse'. and i assume that 'infinity' is the representation of an eternal process.

like the birth and death of an organism. it is eternal, as it is made up of its surroundings, and returns to its surroundings.

the notion that the edge of space is simultaneously the beginning of time (i am not sure anyone still regards this observation?) indicates our limited senses and technology coming to premature conclusions about something unknowable.

i believe the more quantum physicists venture into the infinitessimal, the more unresolvable the paradigm will become.

logic is powerful but limited...
truth is not the representation, but what it represents...
 
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infinity

I think the notion of inifinity is not absolute, beacuse it does not obey the laws that other numbers obey. For the practical purposes there is no harm in taking it to infinity. We can define infinity as a point that we can never reach; so far we know there is part of universe (beyond hubble volume) that is not available to us. In place of asking the question is the universe infinite ? we should make few axioms on the basis of that we can say universe is finite or infite. For example as I mentioned above we can define infity as point that is not casually conntected to us.

cosmoboy
 
I don't think the universe is infinite because infinity is not a well-defined number and so we can't talk about something infinite in any clear terms,whereas all our experience of the universe so far shows that,given time,people can describe the physical world around them clearly and precisely in terms of mathematics which has well-defined numbers.Paul Dirac objected to renormalization in quantum field theory and said that infinities shoyld not be allowed to come into a decent theory in the first place - and this despite the fact that QFT has been verified by experiment to 12 decimal places!
 
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Am I insane? I've read many cosmology books, most popularizations but some that are somewhat academic and as near as I can see the following is stated as the overwhelming scientific opinion (of course, it could change):

1) The universe (at least the one we can observe) is the finite product of the big bang
2) Whether the universe is flat or curved is not yet determined for sure, but an increasing amount of data indicates it is flat.
3) Flat does not equal infinite

The theories of a lot of the respondents are totally new to me -- any references?
 

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