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How will the universe end

  1. Jul 29, 2006 #1
    can anyone explain how universe will end
  2. jcsd
  3. Jul 29, 2006 #2
    sorry i meant to put this quastion in general physics
  4. Jul 29, 2006 #3
    There are three possibilities out there, depending on the total amount of mass in the universe and the expansion speed of the universe.
    1. The expansion of the universe will become slower and slower and eventually stop. Then the universe will contract again to a singularity.
    2. The expansion of the universe will become slower and slower but will never stop.
    3. The universe will expand forever.
  5. Jul 29, 2006 #4


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    http://math.ucr.edu/home/baez/end.html" [Broken]

    Harmony's response is a little outdated (it ignores dark energy). The link above assumes the standard model of cosmology is valid to t=infinity. I don't believe this will be the case, but it's the best guess we have at the moment.
    Last edited by a moderator: May 2, 2017
  6. Jul 29, 2006 #5


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    Just a quibble with John Baez's excellent summary of the present position.
    I think he meant that the pressure of the vacuum due to the cosmological constant is equal to the negative of its density (x c2); it is three times as big (and the reverse sign) as the pressure of a photon gas of equivalent density.

    Last edited: Jul 29, 2006
  7. Jul 29, 2006 #6
    there are a transfinite and possibly infinite possible 'ends' or phase changes for cosmic histories- and QM seems to reveal that ALL of them will happen- just as all possible pasts have occured
  8. Jul 30, 2006 #7
    setAI... I think he's probably curious as to how the universe will end in OUR dimension and our universe, not taking into consideration multiverses and parralel universes.... As it's already been mentioned, theres quite a few numerous outcomes that can happen...

    1. As harmony mentioned, the expansion of the universe can slow down and eventually stop, before collapsing in on itself to form another singularity, most likely to repeat the process of the big bang. (Assuming that the theory is true of course)

    2. Harmony mentioned that the expansion of the universe could either stop, or continue forever. Ultimately these have the same outcomes (given that certain conditions remain true)... Eventually, the in the next 10^12 years, the universe will exhaust its gas by forming new stars.., aind in about 10^30 years black holes will begin appearing at the large gravitational tears of the stars that are dying. I suggest you read more on the "Cold death" theory.

    3. SpaceTiger mentioned dark energy, this is some kind of..opposing force that causes matter to seperate < - >.. If you read Einsteins book of General relativity you can see he labelled this Dark energy the 'Cosmological constant', an equal but opposing force of gravity.
  9. Oct 22, 2007 #8
    several theories exist. most likely would be the big rip, where the universe expands and eventually rips apart particals near the speed of light, eventually making the universe a dull, lifeless place. then the bug crunch. unlikely to happen, due to the universe speeding up. another possiblity is the cold death. it will take quite some time for it to work, but eventually all matter will decay into nothingness.
  10. Oct 22, 2007 #9
    Doesn't the universe annihilate when "I" annihilate?

    Seriously, isn't this what "quantum physics" says?
  11. Oct 23, 2007 #10


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    We will all be dead, so who cares? Seriously though, Harmony gives the three basic options [the Big Rip is a subset of eternal expansion]. What is truly curious is how close the universe appears to being absolutely flat. There is no entirely satisfactory explanation for that apparent fact. It's like a coin flip that lands on its edge.
  12. Oct 23, 2007 #11


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    I don't know if it's exactly a subset--the Big Rip scenario says that the expansion rate goes to infinity in a finite time, which is a type of final singularity (though different from singularities with infinite density obviously).
    Inflationary theory predicts the universe should be extremely close to flat.
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