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Origin of the Uinverse / baby universe

  1. Sep 12, 2008 #1
    I have read that we may someday be able to initiate the creation of a universe in the laboratory. From a layperson point of view, can someone enlighten me. Is this really possible? If it ever happens then the link between the newly created universe and ours would be very brief so would we even know that we had suceeded? A related question, are there any theories dealing with the 'pre big bang' era of our universe or is that still uncontemplated mystery?
     
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  3. Sep 12, 2008 #2
    Alan Guth seems to think that a universe could eventually be created in the lab. As you describe, it should immediately “split off” into its own, well, universe.
    Scientists are going to use the info from the WMAP to see if they can discern some kind of event that would have happened prior to the BB and caused it. No evidence yet.
     
  4. Sep 12, 2008 #3
    There seems to be some confusion regarding the meaning of the word "Universe".
    The definition I find most correct is: The universe is the set of all events.
    Conceivably, a laboratory experiment show that some matter, energy, or information is irretrievably lost to the Universe.
    No evidence for a newly created universe would ever exist, because you can't measure it, being irretrievably lost.
    If, however, an experiment resulted in no loss of matter/energy/information, then by my definition of universe above, it would still be part of our (THE) universe.
    Analogous to the reason why there can be no first hand tales from the afterlife, there can be no evidence for alternate universes.
    So, any claims of a theory of alternate universes is supernatural in nature.

    However, this does not discount entirely theories that such as higher-dimensional membranes, or sum over histories. It just means that these are theories of our universe, not "alternate universes".

    Of course, you can feel free to argue semantics. :rolleyes:

    Now, the term "before the big bang" is as silly as the term "outside the universe".
    There is no time before the beginning of time, and no place outside of space.
    We define the big bang as the first event in the universe.
    Since no events lay outside the universe, no point in time before the first event has meaning.
     
    Last edited: Sep 12, 2008
  5. Sep 12, 2008 #4

    wolram

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    The theory that predicts BHs, is the theory that predicts paradox, time travel, alternate universes, i have no faith in quantum cosmology but by occams razor it is preferable to what we have now.
     
  6. Sep 15, 2008 #5
    Here are links to a couple of papers that got me asking this question:
    http://philsci-archive.pitt.edu/archive/00003196/01/Spec.pdf
    http://arxiv.org/abs/gr-qc/0602084

    semantics and supernatural aside, in asking about 'before' the bang, I was thinking of Hawking et.al. and the boundaryless cone model, in which neither time nor space have and actual beginning point sinc the 'point' can be thought of as a boundaryless surface.
     
    Last edited: Sep 15, 2008
  7. Sep 15, 2008 #6
  8. Sep 15, 2008 #7

    marcus

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    Large research literature on this. Hundreds of papers written about it, even since 2005 (i.e. recent).

    Book coming out next year about this---chapters written by 20 or so of the leading people, presenting their ideas. The book will be called Beyond the Big Bang, the editor is R. Vaas.
    Scheduled for April 2009.

    Amazon has a page on it, they are taking pre-orders even though it won't be shipping for a few more months.
    http://www.amazon.com/Beyond-Big-Bang-Prospects-Collection/dp/3540714227

    I wouldn't latch on to any particular notion, like Hawking's, or like "ekpyrotic" or "cyclic" or "clashing brane". The models of pre-bang that have gotten popularized are likely to be the older ones (1980s and 1990s) and may actually be getting less attention. To find out what kinds of models are being actively pursued you need to look at recent (say since 2005) research and look at what papers get lots of citations from other researchers. A keyword search with the hits ranked by citation-count (most highly cited papers listed first). This gives a clue as to which models the researchers themselves consider most promising or interesting---the ones they cite as references in their own work. It is a fast-moving field, lot of new work.
     
    Last edited: Sep 15, 2008
  9. Sep 15, 2008 #8
    How can we theorize about a thing which has no empirical ramifications, such as past cycles of the universe?
     
  10. Sep 15, 2008 #9

    marcus

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    One should not propose theories which are not empirically testable by observation.
    To do so is not part of science.
    In fact some of the pre-bang models do appear to be testable. In one case there are already explicit predictions on the books which are testable by current technical means. So far the theory has not been shot down, but fresh astronomical data might come in that falsifies it.

    I think it is possible to empirically test some bounce quantum cosmology models that extend to conditions prior to the start of expansion. to test SOME bounce models. But not all. On the whole I think things are in a mess. Several proposed ideas are not testable as far as I can see. Probably the majority are not currently testable.

    =============
    Gendou,
    one of the reasons for the remarkable growth in LQC papers in just the past two or three years is the very thing you mention, testability.
    Several recent papers that I've seen address this. What we see is new people coming in to the field and I think they are very likely attracted, in part,
    by the fact that there are computer models of the bounce, as well as exact analytical models, and that one may be able to make predictions----for example as to how this would affect structure formation in the early universe.

    The bounce also may have the possibility to replace the inflation hypothesis---which does not have a completely solid empirical foundation---as an explanation for what is called the 'horizon problem'. This is iffy, but inflation is merely one possible scenario which explains certain cosmological features----these may have alternative explanations, leaving inflation unproven. Some combination of LQC with inflation might emerge. Or one may win out over the other. There being some competition to explain the same things some overlap of what they predict.

    Here is an assortment of recent Quantum Cosmology papers, some are Loop and some not.
    http://www.slac.stanford.edu/spires...+DATE+>+2004&FORMAT=www&SEQUENCE=citecount(d)
    the most highly cited are listed first. you can look over and get an idea of what's happening if you wish.
     
    Last edited: Sep 15, 2008
  11. Sep 16, 2008 #10
    Interesting, thanks marcus.
     
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