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Questions of String Cosmology

  1. Nov 10, 2005 #1
    This might be posted on the Cosmology Forum. But I think it's more likely to get answers here:
    1. Is inflation as in the Big Bang coincident with compactification?
    2. Is the compactification of 6 dimensions most likely or could other numbers of dimensions be just as likely?
    3. I read that there may have been two inflations in the Big Bang. Is this likely?
    4. If 3 is so, and I read of Randell & Sundrum's claim for larger dimensions in Scientific American (i.e., our universe lives on a brane in the larger dimensions), could the first inflation be a compactification that produced the larger dimensions, and the second inflation be a compactification that produced our universe?
    5. If 26-d string theory has two time-like dimensions, then is it likely that the first inflation produced the larger 4-d spacetime and the second produced a smaller 4-d spacetime, our universe.
    6. If all of the above is likely, then is it likely that the second inflation is coincident with two sets of 6-d compactifications, one which in superstring theory produced fermions, and the other which produced the supersymmetric partners of the fermions?
    If all the above is still likely, then I suggest that the (electric-charge) neutral supersymmetric partners possess a different type of charge that acts analogous to electric charge, and that initially in the Big Bang, anti-symmetric partners were produced and recombined just like the anti-fermions did. That implies that dark matter is composed of the supersymmetric particles left over from recombination, but with a mass comparable to fermions
    I also propose that in both cases the anti-particle/particle pairs before recombination were connected by threads of the most elementary form of compactified dimensions, and that at recombination these threads precipitated into 3-d space into what are called cosmic axions. If so, then dark matter is composed of both axions and supersymmetric partners, but with axion mass being dominant.
    Is there a clue in all this as to what Dark Energy could be?
    I of course expect these questions and propositions to be falsified on general principles, or at least this post to be moved to a development subforum with all the other outrageous proposals.
  2. jcsd
  3. Nov 11, 2005 #2
    Hi Yanniru
    Glad to see you here again. I hope your post doesn't get moved, but it hasn't so far, so maybe there is hope. I think it does address problems in quantum gravity, so my opinion is that it is at home in this thread.

    Inflation has been pretty well accepted into standard cosmology, I think, but the rest of it is still speculation. For example there is still no evidence for supersymetric partners.

    I have also wondered if compactification should be connected to inflation. It seems possible. But the whole extra-dimensions thing is still math, not physics.

    I think your ideas may be prescient, but we will have to wait for more information from the experimentalists before making any conclusions.

    I am sorry I can't give you any real answers, but am pleased to offer you conversation.

    Be well,

    Richard T. Harbaugh
    (previously, nightcleaner)
  4. Nov 14, 2005 #3
    Seems there are some papers on the subject of inflation due to compactification in spite of an earlier suggestion of a no-go theorem for accelerating string theories.

    Here is one referenced in this Physics Forum by ranyant:
    which I found from Googleing inflation/compactification

    They find that only hyperbolic superstring cosmologies inflate.

    An earlier paper http://arxiv.org/PS_cache/hep-th/pdf/0303/0303097.pdf suggests a way around the no-go theorem for inflating compactifications for hyperbolic spaces.

    An intermediate paper is more positive about circumventing the no-go theorem:


    So it seems possible that inflation is caused by compactification, but it is not clear how likely it is.
  5. Nov 22, 2005 #4
    Such physicists as Linde and Maldacena and a few others wrote a paper a few years ago suggesting that work be done on linking compactification and inflation. Since then we have had several papers on the link and then some others on multiple inflations, not related to compactification. The most recent 'link' paper is:

    Stringy Effects during Inflation and Reheating.
    Andrew Frey

    Likewise, the most recent paper on multiple inflations is:

    Multiple Inflation, Cosmic String Networks and the String Landscape
    C.P. Burgess, Richard Easther, Anupam Mazumdar, David F. Mota, Tuomas Multamaki
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