Is the Universe Infinite?

Discussion in 'Physics & Math' started by Captain Kremmen, Feb 11, 2010.

  1. quantum_wave Contemplating the "as yet" unknown Valued Senior Member

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    My understanding is that observations and data tell us that the galaxies and galaxy groups are moving away from each other at an accelerating rate. Is there any evidence that the space through which they are moving has not always existed and is not already infinite?
     
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  3. Beer w/Straw Transcendental Ignorance! Valued Senior Member

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    Screw off
     
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  5. Captain Kremmen All aboard, me Hearties! Valued Senior Member

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    A slightly better answer than "screw off", succinct though it is, is that the galaxies are not physically moving away from each other, but that it is space itself which is expanding.
    Only this way can you explain the fact that furthest reaches of the small portion of the universe that we can see is 80 billion light years away, and the age of the universe itself is only c 14 Billion years.
    It must be the space which is expanding faster than light, as it is impossible for matter to do so.


    @beer
    Almost as if I can see forward in time, I predict that you are very close to being banned.
     
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  7. quantum_wave Contemplating the "as yet" unknown Valued Senior Member

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    Captain, you are close to reciting the consensus Big Bang Theory. It might be time for me to update what I call Big Bang Theory and I am open to being corrected but I understand it to be General Relativity, Inflationary Theory, the Cosmological Principle, and two developing areas related to unexplained accelerating expansion attributed to dark energy and the unexplained motion of galaxy rotation attributed to dark matter. In BBT explanations for dark energy and dark matter have not yet reached a consensus.

    The 80 billion light years to distant galaxies that you mention is explained by Alan Guth’s Inflationary Theory.

    Your consensus explanation of space stretching fits with my layman’s view of the General Theory of Relativity where spacetime carries the galaxies with it as it inflates or expands. Expansion is measured by the relative motion of galaxies. They are observed to be moving away from each other in all directions at an accelerating rate. That is what beer /w straw (sock puppet?) was saying proved that the universe is not infinite. In my reply to him I just was raising the question about space pre-existing the Big Bang. If space did already exist it could be just emptiness waiting for something like the Big Bang to occur

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    .

    All I am saying is there is nothing in the observations that I know of or that anyone has ever told me that precludes space already being there. If it was already there that would provide a convenient place for Guth’s inflation and for the subsequent formation and separation of the galaxies to occur within spacetime. That would eliminate questions about the nature of space and would allow it to just be a potentially empty place that has always existed. Then we wouldn’t have to give space any special characteristics like the ability to stretch, and if it is stretched is there any resistance to further stretching and if so why is it stretching faster instead of slower.
     
  8. Beer w/Straw Transcendental Ignorance! Valued Senior Member

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    Why would I be close to being banned? I answered your question succinctly as possible.

    For all I know, you and QW are disingenuous.
     
  9. BenTheMan Dr. of Physics, Prof. of Love Valued Senior Member

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    Banned for three days.

    Mgmt.
     
  10. prometheus viva voce! Registered Senior Member

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    I believe the CMBR is evidence that the universe is actually expanding, meaning it's not just galaxies moving away from each other.
     
  11. quantum_wave Contemplating the "as yet" unknown Valued Senior Member

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    My understanding about the Cosmic Microwave Background Radiation is that it is causally connected to the big bang and it confirms Guth’s view of Inflation. The exponential inflation had to take place before stars and galactic structure formed. It is the “echo” of the big bang in the sense that the thermal radiation from the Big Bang that was thought to be billions of degrees has cooled to the present ~2.7 K as a result of inflation and expansion. The CMBR being essentially homogeneous and isotropic is what ties it to the Big Bang. I don’t see how it says anything about pre-existing space one way or the other but I would like to be corrected on that if I am wrong.

    Now as for it being evidence that the universe is actually expanding I would say that its current temperature is an effect instead of a cause of expansion. And the observation of galaxies and galaxy groups all moving away from each other at an accelerating rate is not explained by the CMBR, it is compatible with our observations of the CMBR. Like I said in my last post, it is my understanding that the accelerating expansion is attributed to dark energy for which there is no current consensus in BBT. Would someone correct me about that if I am wrong?
     
  12. prometheus viva voce! Registered Senior Member

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    The CMBR wasn't formed until about 300,000 years after the big bang when the universe was cool enough for nuclei and electrons to combine into atoms. The reason that the CMBR is homogeneous and isotropic is because that's how the universe was when it was emitted, which further implies that that's how the universe was before then, otherwise you have a problem of a system that isn't homogeneous and isotropic spontaneously getting those features.

    Who said the CMB is causing the expanding of the universe? Not me. The CMB is evidence that the universe is expanding. As far as I'm aware, measurements from the CMB agree with what we deduced about the expansion of the universe from the motion of galaxies - Hubbles law for example.
     
  13. quantum_wave Contemplating the "as yet" unknown Valued Senior Member

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    I understand that. I said that the CMBR is causally connected to the Big Bang. You seem to agree.
    I know you didn’t. If I may try to paraphrase our most recent exchange:

    I am saying that the fact that the galaxies and galaxy groups are moving away from each other is not evidence that space is stretching because of the possibility that space could have already existed prior to the Big Bang. I say that space could be infinite and could just be a potentially empty place other than the fact that our known universe occupies some of that space. I am suggesting that if space is infinite then the universe is spatially infinite even if our observable or known universe has a finite volume. Is that what you thought I was saying?

    I think you are saying that the universe is expanding and expansion equates to an increase in the total volume of the universe, i.e. the universe does not have infinite volume like it would if it was spatially infinite? I think you are agreeing with Captain Kremmen, and I think you are agreeing with the standard Big Bang Cosmology that says that the universe, space and time began with the Big Bang singularity? I could be wrong about what you are saying so correct me if I am.

    I don't think you are addressing the issue of accelerating expansion which I mentioned in my response to Captain Kremmen and Beer w/Straw are you. I am saying that the cause of acceleration is not part of the Big Bang consensus yet but that it is referred to as dark energy that we don't yet understand completely.

    Do you have a position on what dark energy is or what is causing the accelerating rate of expansion?
     
  14. noodler Banned Banned

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    There is also the possibility that the region of the universe we're in is special, by having a much lower density than the surrounding universe, like this part is a big bubble in a swiss-cheese universe. The bubble is expanding because the denser part surrounding it is cooling and shrinking.
    That would mean the "real" universe is a lot clumpier than the part we're in.

    We happen to be near the center of the bubble, and see distant galaxies receding to infinite redshift.
     
  15. Captain Kremmen All aboard, me Hearties! Valued Senior Member

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    Swiss cheese universe.

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    I like it.
     
  16. sniffy Banned Banned

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    If the universe were infinate wouldn't anything be possible?

    And 'anything' doesn't seem to be....
     
  17. Smellsniffsniff Gravitomagnetism Heats the Sun Registered Senior Member

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    If the universe was an answer to a question as to how big all things are together then I suppose a singularity that is infinite in relativistic mass would have been braking its boundries a long time ago. That is why the universe is infact a place where all dimensions exists together and with sizes and numbers beyond infinity. A singularity would have atleast an infinity of dimensions, that I assume since it answers the question how many dimensions an object that is unchanged even though it surrounding is absorbed. The only answer is that it is the factor one, and 1 is the fusion of all dimensions. Hence infinity is only one singularity, and the universe contain an endless plain of the buildingblocks of one. I assume that everything has the multiple one now adays since our souls are unchanged even though we know things with them. You wouldn't know a thing unless your soul is not the answer of the query and only one goes unharmed through a multiplication. Therefor there is a singularity in the universe and we have the factor one from a relativistic mass increase from it. That is why a black hole will blow up soon, because it has infinite energy in it, in the form of a photon that is infinite and a singularity in nature. Questions?
     
  18. Captain Kremmen All aboard, me Hearties! Valued Senior Member

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    Interesting idea.
     
  19. Smellsniffsniff Gravitomagnetism Heats the Sun Registered Senior Member

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    If it did not, it would not have been disolved into a singularity, since a black hole has infinite mass, and a singularity is a black hole that behaves as a particle.
     
  20. fadingCaptain are you a robot? Valued Senior Member

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    The universe is expanding. There are clusters of energy/matter. No, the universe is not infinite. The real question is whether it is bounded...
     
  21. quantum_wave Contemplating the "as yet" unknown Valued Senior Member

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    The evidence shows that the univese is essentially flat and if it is flat that means that it is spatially infinite if these two links can be taken at face value:

    http://map.gsfc.nasa.gov/universe/uni_shape.html

    "Recent measurements (c. 2001) by a number of ground-based and balloon-based experiments, including MAT/TOCO, Boomerang, Maxima, and DASI, have shown that the brightest spots are about 1 degree across. Thus the universe was known to be flat to within about 15% accuracy prior to the WMAP results. WMAP has confirmed this result with very high accuracy and precision. We now know that the universe is flat with only a 2% margin of error."

    Page Updated: Thursday, 11-19-2009

    http://www.spacetimesociety.org/Monton2.html

    "There is a good amount of evidence for the hypothesis that the space is infinite. For example, empirical measurements of the global curvature of spacetime suggest that spacetime is globally flat, which entails that the universe is spatially infinite."
     
  22. Captain Kremmen All aboard, me Hearties! Valued Senior Member

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    I think that the person you quoted in the Spacetime society, has misunderstood the measurements of the WMAP probe, which indicate that spacetime is flat.

    Their figures indicate that the Universe will continue to expand, because the amount of matter in the Universe is not enough to counteract the rate of expansion. The force of gravity will not cause expansion to slow and eventually bring all the matter together again in a "big crunch".
    Thus the Universe will expand forever.
    That doesn't mean that it is infinite.
     
  23. quantum_wave Contemplating the "as yet" unknown Valued Senior Member

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    That is possible. Here is a page on Monton and what his background is. I'd say his primary focus is philosophy of science and though he is an atheist he wrote a book that was not unkind toward Intelligent Design.

    And you are correct that the concept of a flat or open universe in relativistic terms means that the universe will expand forever and does not mean that space did not come into existence at the instant of the Big Bang. Nothing that I know of can prove or disprove the infinity of space. No one that I know actually claims that space is not infinite even though our known universe is finite in energy content. Relativists can be found who will agree that the universe began with a singularity, i.e. the zero volume infinitely dense point but they don't insist that there is only one singularity for that matter.

    The question of if the universe is infinite spatially cannot be tested and will always boil down to a choice between "we don't know" and speculation.
     
    Last edited: Feb 23, 2010

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