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The end of the universe

  1. It will keep expanding

    12 vote(s)
    42.9%
  2. Universe reverses expansion and crunches

    5 vote(s)
    17.9%
  3. Big rip in the fabric of spacetime

    2 vote(s)
    7.1%
  4. other

    9 vote(s)
    32.1%
  1. Jun 2, 2010 #1
    Just curious about how people think the universe will end.
     
  2. jcsd
  3. Jun 2, 2010 #2

    nicksauce

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    Not sure why you need or want a poll for this. This is a question that can be objectively answered my looking at observational data. Current data favours a scenario where the universe continues to expand forever, although the possibility of a big crunch type end is not ruled out.
     
  4. Jun 2, 2010 #3
    I read an article in a back issue of skynews that said that an American astronomer thought that the galaxies would get so distant that they would be red-shifted beyond the visible spectrum. This process would completely make it impossible for future civilizations to theorize the big bang without a history in astronomy. The good news is that this process would take 3 trillion years. And I was just curious Nick.
    cheers, BT
     
  5. Jun 3, 2010 #4

    marcus

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    that's not anything new, and it falls under the heading of "keep expanding".

    What you may have read about was an article by Larry Krauss, a top mainstream cosmologist (who also has written popular books). I'm a fan.

    He follows the standard (LambdaCDM) model out into the far distant future as it "keeps expanding" with steady mild acceleration---no "big rip" is foreseen. LambdaCDM is a remarkably good fit to the data so increasingly is the only model anyone in the profession uses.

    And he comes to the obvious conclusion that after a long while we won't be able to see any galaxies except our own. So if life evolves on some future planet and future astronomers evolve and look thru their telescopes they won't be able to see any other galaxies. So they won't be able to figure out that the U is expanding.

    When you think about it, it's pretty obvious and straightforward. But a journalist could hype it up and make it seem radical, I guess.

    In any case the actual article by Larry Krauss is excellent and you could go straight to it and get quite a bit out of it. I will get the link. Just google "krauss end cosmology" if you want.

    This is the original article
    http://arxiv.org/abs/0704.0221
    The Return of a Static Universe and the End of Cosmology
    Lawrence M. Krauss (1,2), Robert J. Scherrer (2) ((1) Case Western Reserve University, (2) Vanderbilt University)
    (Submitted on 2 Apr 2007 (v1), last revised 27 Jun 2007 (this version, v3))
    We demonstrate that as we extrapolate the current LambdaCDM universe forward in time, all evidence of the Hubble expansion will disappear, so that observers in our "island universe" will be fundamentally incapable of determining the true nature of the universe, including the existence of the highly dominant vacuum energy, the existence of the CMB, and the primordial origin of light elements. With these pillars of the modern Big Bang gone, this epoch will mark the end of cosmology and the return of a static universe. In this sense, the coordinate system appropriate for future observers will perhaps fittingly resemble the static coordinate system in which the de Sitter universe was first presented.
    Comments: 5th prize 2007 Gravity Research Foundation Essay Competition.

    It doesn't mean that the U actually becomes static or that cosmo ends. It just means that it becomes very hard for future people to DISCOVER that it is expanding. The actual expansion goes on and on at a slowly accelerating pace. But the future people can't tell so they think their own galaxy is the only thing in the universe. (Galaxies do not expand, so for them everything stays the same, or static.)

    Krauss article was picked up the the Sci Am, and there is a popularized version that you can also find with google. Fun, but not a big deal.
     
    Last edited: Jun 3, 2010
  6. Jun 3, 2010 #5
    it will expand forever and we will freeze to death
     
  7. Jun 6, 2010 #6
    I put other, because in reality we do not know. The universe is presently expanding and will likely do so for its viable history as a universe. How does a universe actually end or just disappear in cold death if there is no reversal, we do not know.
     
  8. Jun 6, 2010 #7
    When you mean "end", do you mean for human kind? I think it will continue to exist even though we are gone.
     
  9. Jun 9, 2010 #8
    Have any of you heard of the big chill? The theory is that black holes will eventually consume all the matter in the universe and then decay leaving an empty void like place.
    I put other but this is one of what I think are the better theories. I should have voted keep expanding.
    caught my mistake, BT
     
  10. Jun 9, 2010 #9
    I am new, and voted that it will keep expanding. It is the safe bet to me, unless the string theorists' membranes are right. That might be other.
     
  11. Jun 9, 2010 #10

    Math Is Hard

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    Not with a bang
    but a whimper.
     
  12. Jun 9, 2010 #11
    Cosmology does not rest on safe bets.
    There are possibly more options that membranes, and we do not all the possible options that may come to light in the future.
     
  13. Jun 10, 2010 #12
    However M-theory is the best we currently suppose. Right?

    cheers, BT
     
  14. Jun 10, 2010 #13
    M-Theory is the conjecture offshoot of String Theory, which is also conjecture. That is not a safe or unsafe bet, it is a matter of cosmology versus undemonstrated and possibly undemonstratable fantasy.
     
  15. Jun 11, 2010 #14
    Can the universe expand faster then the speed of light?
     
  16. Jun 11, 2010 #15
    After the inflationary epoch, I don't think so. Are you thinking of galactic recession speeds as a result of expansion? That is a somewhat different matter.
     
  17. Jun 15, 2010 #16
    How about this.
    Space is infinite and portions of it are filled with matter.
    Our "observable universe" is made up of some of this matter and is expanding.
    Who is to say that other portions of space are not also filled with matter that has created galaxys, suns and planets etc. ( Multiverse theory )
    Simply, we zoom out from our solar system and observe more stars sytems, zoom out more and see our galaxy, zoom out again and see more galaxys and observe that they are travelling away from each other, zoom out much more and observe other area's of space are undergoing the same process. ( take a A3 piece of paper, drop several grains of sand on it, one of those is our " observable universe. There are infinite sheets of A3 sheets. )
    How it will end? If it all drifts away, then surely all the galaxys will eventually become dead and drift through space and all matter from our " observable universe " will drift further apart so no Big Crunch. Just drifting dead stars and planets.
    Would the matter drift and become attracted to other drifts of matter from other dead universe systems? Given enough time of course. As these drifts gather more material could there be a tipping point where it collapses or something and fuels a runaway recycling proceedure that is essentially a big bang?..... This could go on forever and may already have been. Think big.
     
  18. Jun 15, 2010 #17
    We could call it universal mitosis.
     
  19. Jun 15, 2010 #18
    What is another universe if not a region with a different set of physical constants? If the universe is infinite, and infinitely expanding then recession speeds still mean our observable region will "die" and expand eternally. If you mean that there are separate universes from ours, not within the same spacetime, then Blandrew is making the right point, and the expanding dust and radiation will define the edge of our spacetime. To move from one set of physical constants to another, another universe, requires more than expansion in our 3+1 space and time.

    I've read magazine-level multiverse theories of "bubble" universes eventually colliding, but what happens then is really just a guess. I find it hard to believe that, if they interact at all, it would be a simple merger like two galaxies; the best guess I've heard is that they might pass through each other, or that the cosmological constant of a given universe would make it overwhelming fo the other.

    So, we have infinite space and more homogeneous isotropic "stuff" outside of our view, but within the same universe, in which case recession speeds mean they never meet, different dimensions or membranes, in which case they never meet, or bubbles which MAY meet, but will have different "laws of physics" and are unlikely to get along.
     
  20. Jun 15, 2010 #19

    Entropee

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    Quick question. If all the galaxies are red-shifted beyond the visible spectrum, wouldn't people theoretically be able to detect the x-rays and gamma rays emmitted from them? That is... if there is some sort of history they can reflect on that shows what is really out there. Also, I think something unexpected will happen in the universe, it is a mysterious place afterall.
     
  21. Jun 15, 2010 #20
    Your question seems to be a combination of two notions, the first being galactic recession speeds, and after some long period of time, nothing would be detectable. The other relates more to our limit in looking to around 380,000 years after the Big Bang, the CMB. We already see what is "out there" such as the AGNs that are Quasars. We can't see beyond the CMB directly however.

    Betting on a surprise is safe, but too vague to be meaningful.
     
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