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Number of galaxies

  1. Jul 5, 2003 #1
    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
  2. jcsd
  3. Jul 5, 2003 #2
    well of course because infinity is not a number

    ... but what is YOUR reasoning?
  4. Jul 5, 2003 #3
    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
  5. Jul 5, 2003 #4
    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}}}
  6. Jul 5, 2003 #5


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    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.


    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 cant see we cant 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"
  7. Jul 5, 2003 #6
    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)
  8. Jul 5, 2003 #7
    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?
  9. Jul 5, 2003 #8
    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.
  10. Jul 5, 2003 #9

    In reality we don't know if the universe is infinite in extent or not. And the big bang is a modern creation myth.
  11. Jul 5, 2003 #10

    MYTH? Now how absurd do you sound.

    The big bang has been proven in more than 100 independant 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.
  12. Jul 5, 2003 #11
    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
  13. Jul 5, 2003 #12

    haha - this guy thinks the BB is a myth

    Everyone laugh at him hahahaha!
  14. Jul 5, 2003 #13
    Excellent argument!! Everybody heckle the non-believer!!!

    A desperate appeal to the mob mentality.
  15. Jul 5, 2003 #14

    Yeah well - come on now - your claim is so absurd it isn't worth debating! It's worse than creationism!
  16. Jul 5, 2003 #15
    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.
  17. Jul 5, 2003 #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.
  18. Jul 5, 2003 #17


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

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

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

    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.
  19. Jul 5, 2003 #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.
  20. Jul 5, 2003 #19


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    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.
    Last edited: Jul 5, 2003
  21. Jul 5, 2003 #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.
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