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Universe will end in 5 billion years?

  1. Aug 30, 2013 #1
    Found this article:

    http://news.nationalgeographic.com/...ce-universe-end-of-time-multiverse-inflation/

     
  2. jcsd
  3. Aug 30, 2013 #2

    marcus

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    I sort of remember when that paper came out back in 2010
    http://arxiv.org/abs/1009.4698
    There was a flurry of skeptical interest. Not much came of it.

    Popular science writing will often make something SEEM more plausible than it is.

    Charles Lineweaver's reaction is probably fairly typical.
    We don't know that "eternal inflation" is right and at least one version of it leads to an implausible conclusion. This is useful as a reductio ad absurdum. He says the Bousso paper makes him more inclined to take seriously the criticism of eternal inflation. In other words to seriously question the assumptions.

    Lineweaver is a world-class senior cosmologist. Bousso is a string theorist whose research is no primarily in cosmo.
    I have not heard anything about the paper for the past couple of years. So I guess it has pretty much been forgotten.
     
  4. Aug 30, 2013 #3

    marcus

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    I don't know if anyone wants to take the time to go back to the 2010 Bousso et al paper and follow thru on it. If you do want to take it seriously, you might want to look at this 2011 paper by Ken Olum in 2011. It was motivated in part as an answer to the Bousso et al. which Olum cites as his reference [3] in the introduction:
    http://inspirehep.net/record/1089145
    Is there any coherent measure for eternal inflation?
    Ken D. Olum (Tufts U., Inst. of Cosmology)
    Feb 2012 - 10 pages
    Phys.Rev. D86 (2012) 063509
    DOI: 10.1103/PhysRevD.86.063509
    e-Print: arXiv:1202.3376 [hep-th] | PDF
    Abstract: An eternally inflating universe produces an infinite amount of spatial volume, so every possible event happens an infinite number of times, and it is impossible to define probabilities in terms of frequencies. This problem is usually addressed by means of a measure, which regulates the infinities and produces meaningful predictions. I argue that any measure should obey certain general axioms, but then give a simple toy model in which one can prove that no measure obeying the axioms exists. In certain cases of eternal inflation there are measures that obey the axioms, but all such measures appear to be unacceptable for other reasons. Thus the problem of defining sensible probabilities in eternal inflation seems not be solved.
    10 pages.

    Olum is one of those skeptics quoted along with Lineweaver in the National Geographic article. This paper is part of his reaction to the kind of thing the Bousso et al authors were doing in their 2010 paper.
     
    Last edited: Aug 30, 2013
  5. Aug 31, 2013 #4

    Chronos

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    Why 5 billion years, why not 20 billion years?
     
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