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Beyond the Big Bang

  1. Jan 27, 2014 #1
    I read

    Where can I read theories on what the universe is expanding into and what gave rise to the big bang?
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  3. Jan 27, 2014 #2


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    The only place I can think of where you would find theories that space is expanding "into" something is on crackpot forums, since mainstream science rejects any such idea (and with good reason)

    As for the other, try "brane cosmology", but keep in mind that it is speculative and has zero evidence of being real.
  4. Jan 27, 2014 #3


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    There is an area of research called "quantum cosmology". One way to find research articles on conditions around the start of expansion, and what could have led up to it, is just to do a keyword search in the professional literature. Here are the "quantum cosmology" research papers since 2009:

    "quantum cosmology" since 2009, Inspire search:
    http://inspirehep.net/search?ln=en&...search=Search&sf=&so=d&rm=citation&rg=25&sc=0 (647 found as of 27 Jan 2014)
    "quantum cosmology" or "ekpyrotic" Inspire search:
    http://inspirehep.net/search?ln=en&...search=Search&sf=&so=d&rm=citation&rg=25&sc=0 (698 as of 27 Jan)
    "quantum cosmology" and not "loop" since 2009, Inspire search:
    http://inspirehep.net/search?ln=en&...search=Search&sf=&so=d&rm=citation&rg=25&sc=0 (322 as of 27 Jan)

    You can see that about half the QC papers are Loop Quantum Cosmology (LQC) which gets rid of the singularity by shifting over to a QUANTUM version of gravity. Then quantum effects cause gravity to REPELL rather than attract, at extremely high density. A contracting phase of the universe would reach extreme density and REBOUND rather than collapse into a "singularity".

    According to this theory the idea of a "singularity" (infinite density) is unrealistic. It is a failure of the classical (pre-quantum) theory of general relativity that it predicts collapse to an unnatural infinite density. LQC predicts a "big bounce" occurring at a high, but nevertheless finite density.

    LQC is only about half of the QC research. About half use various alternative non-loop models.

    LQC is a class of cosmic models, from some of which TESTABLE PREDICTIONS have been derived.
    Some of the first 20 or 30 papers that you see in the QC listing are about LQC testable predictions. this is called "QC phenomenology" (i.e. what phenomena to look for in the sky, especially the CMB ancient light, the cosmic microwave background).
    Phenomenology authors to look for are Aurelien Barrau, Julien Grain, and their co-authors.

    There is also a class of models under the name "ekpyrotic" which don't all come up when you use the keywords "quantum cosmology". You can see that adding that additional keyword to the search will get you about 50 more papers, bringing the total from 647 up to 698.
    In the ekpyrotic models there is a different kind of bounce, not caused by quantum gravity corrections at high density. There is currently not much research devoted to that so I won't discuss it, but others here might want to.
  5. Jan 27, 2014 #4
    Thanks. Except the more information there is the less interested I am. So I'm mostly interested in whether the universe expanded into anything. I've heard the possibility of an infinite number of universes being discussed by people who seem to know what they're talking about (someone on TV). Would they be considered not spaced from each other by anything at all? When one expands, does it overlap the other while not affecting it?
  6. Jan 28, 2014 #5
    We are making a series of films, free on Youtube focusing on competing models for the origin of the big bang.
    The first is on loop quantum cosmology that MArcus described above:
    The second is on Conformal Cyclic Cosmology from Rger Penrose (the big bang singularity picture is based upon theorms develoepd by Roger Penrose and Stephen Hakwing):
    If you subscribe to our channel you will see more on other models.
    The films are around 40 mins each and we try explpain each model to the layman and put some of the difficulties of the models to their inventors and see how they respond.
    Needless to say we do not know which if any of these mdoels are correct at the moment, maybe one day we will , its a work in progress.
  7. Jan 28, 2014 #6
  8. Jan 28, 2014 #7
    Thanks for the link. I'm a fan of CCC for quite sometime now. ^^

    Here is good discussion on something beyond.. Check on the playlist:

    Last edited: Jan 28, 2014
  9. Jan 30, 2014 #8
    I highly recommend to read the papers of George Ellis on Multiverse and philosophical (But inevitable) aspects of current Cosmology , which often unfortunately is neglected.
  10. Jan 30, 2014 #9


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    Philosophical but inevitable? Really? How about just philosophical.
  11. Jan 30, 2014 #10


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    I'm always intrigued by philosophical perspectives of scientists of the pedigree of George Ellis. They always seem well reasoned and interesting. Perspectives of lesser luminaries, not so much. I suppose that constitutes reputation bias.
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