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Before the Big Bang

  1. Nov 30, 2004 #1
    I'm looking for any information available concerning what "was" before the Big Bang. Anyone that can help? Thanks
  2. jcsd
  3. Nov 30, 2004 #2
    Possibly you have heard about the Ekpyrotic universe, and also about the Cyclic model, or perhaps about the Pre-Big Bang Scenario. There's a model called Colliding Bubble Braneworld Scenario, that is not so well known. this model was proposed in 2002 by Bucher. Here's a paper about it
    When do colliding bubbles produce an expanding universe?
  4. Nov 30, 2004 #3
    It's possible that this is a contradiction of terms. If the universe started from a singularity, then no information from a prior cycle is obtainable in this cycle. In fact it is most likely the case that the entire information content of this universe is zero. If there is no alternative but that this universe exist, then a 100% probability results in zero information content.
  5. Nov 30, 2004 #4
    Another theory that investigates what happened before the Big Bang is the Cyclic Universe of Ding-Yu Chung (not to confuse with the Cyclic Model of Paul Steinhardt that was proposed a months later). In the Cyclic Universe, the Big Bang occurs as a collision of two branes. Here's the paper where this model was proposed
    The cyclic universe
  6. Nov 30, 2004 #5


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  7. Dec 1, 2004 #6


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    how technical do you want to go? there is lots to read but it is not so easy to sift thru or assimilate.

    do you want numerical calculation concerning before expansion started?
    or do you want just a popularized account of somebody's hypothesis?

    it is possible to numerically model the universe around the start of expansion and to extend back in timne somewhat prior to that, and to get two things:

    1. predictions which in principle can be tested to see if the model fails or not-----different start-up models leave different imprints on the early radiation background called the CMB

    2. good behavior in the largescale limit----after a brief time the models give a good approximation of the known behavior of the universe in standard cosmology. they just remove the breakdown or "singularity" of the standard model that happened right around start of expansion.

    the two approaches farthest along in these two specific ways are LQC and CDT (loop quantum cosmology, causal dynamical triangulations).
    the bestknown experts are Martin Bojowald (LQC) and Jan Ambjorn and Renate Loll (CDT). Search under those names and you will find a lot of stuff online.

    So yeah, it is possible to talk scientifically about pre-expansion, and to make testable predictions. so this is not mere speculation. But it is new stuff (all since 2001 and most of it from this year---no more than a year old) and the observational tests have not been done.

    Both LQC and CDT, which are used in computer simulations and have reached the level of numerical detail, are rather solid down-to-earth affairs. They dont involve imaginary "extra dimensions", or "ekpyrotic colliding brane-worlds in higher dimensions" or comparable mental baggage---they just involve ordinary 4D-----3D space plus time.

    And they use modern quantum versions of the Einstein equation that has been standard in cosmology since around 1920. So technically-speaking no big leaps, but they dont make for simple reading! Both models do give pictures in the sense of computer plots of various stuff right at start of expansion and just before, but it is abstract. And the pictures are few and far between, mostly there's just formulas, charts and technical language.

    so the question is, how bad do you want to know and how deep do you want to go?

    I guess there is one popular "Scientific American"-type article online. Translated from a German magazine. It is by Rudi Vaas and the title is
    "The Inverted Big Bang". It only covers LQC and doesnt do the other.
    I havent read it so i cant say how good it is. It is on this download menu:

    this menu has a lot of good semipopular articles, you just have to find the title "The Inverted Big Bang" and click on it. He also has the original version in German, which has more pictures.
  8. Dec 1, 2004 #7
    Thanks to everyone. This should give me more than enough to consider for awhile. I will need to get back to all of you for clarification if you don't object. Thanks again.
  9. Dec 1, 2004 #8


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  10. Dec 1, 2004 #9
    so Marcus...

    I was reading that article not 2 days ago and it says LQG inverts our universe into a left-right/mirror image configuration at the point of a big bang and then inflationary processes take over. Like a balloon getting sucked through it's opening and turned inside out.

    So where did the inverse universe that blew out to become ours come from???...The black/white hole baby universe factory...sounds rather cylclic to me
  11. Dec 1, 2004 #10


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    that eversion of the volume element is a fascinating part that I dont understand the significance of

    in one of Bojowalds earliest papers he mentioned it, maybe even the 2001 paper "Absence of Singularity in Loop Quantum Cosmology" (can find on arxiv)
    I remember reading it and wonder what it can mean that "positive volume becomes negative volume" or something.

    I cant help here. It is a weird unexpected thing that comes out of the math.

    about language (I love language) there is the point that when you turn a sock or mitten inside out you EVERT it.
    This word is in any good dictionary and it means turn inside out.

    Invert has a slightly different meaning, more like turn upside down, like a drinking cup, which is different.

    But English speakers have gradually been losing touch with the word evert and so it is getting replaced by the next best thing which is invert.

    this is a badness of English
    in German one can say umgestülpte which means turned inside out or everted. It is what you do with a worn collar or cuff of a shirt. Wives sometimes do this. It is a kind of mending that gets more wear.

    another translation of umgestülpte would be "reversed" like you reverse your jacket by turning it inside out---but that has too much the sense of backing up---going in reverse.

    English is an excellent language but the Germans, instead of saying Big Bang, say Urknall------ur means ancient primordial and knall means bang.
    It makes me wonder if more people shouldnt learn German.

    at the moment that contraction changes over to expansion, it is a "quantum moment" when usual intuition is not going to make too much sense, and things somehow pass through each other and become turned inside out.
    But I am clueless.

    maybe it at a moment like this that a high entropy state can be turned
    upside down into a low entropy state

    so that the universe can start refreshed with nice low entropy again

    or maybe thermodynamics is meaningless at that moment.

    maybe matter is affected by this eversion.
    maybe the turning inside out does not mean anything and things are just business as usual

    this is something that has me quite baffled and I have not heard any interpretation

    you find it in Bojowald's papers about removing the BB singularity but I dont recall anyone interpreting it
    Last edited: Dec 1, 2004
  12. Dec 1, 2004 #11
    yeah language sux...

    ...can't wait to get the whole jump inside someone elses mind and cut out the words thing and get right down to the nitty gritty

    ...thanx for the new word e-vert could also be like a convert to the interweb and but for a misplaced vowel coud be avert as in to turn one's eye away

    Do you remember the planet bizarro from superman comics ???
  13. Dec 1, 2004 #12


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    Jacobi, who discovered the elliptic functions by inverting the elliptic integrals, said man muss immer umkehren, interpreted as "you must always invert". Sorry, I'm too lazy to do the umlauts.
  14. Dec 1, 2004 #13


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    you didnt miss any umlauts :smile: none needed
    no one minds on the internet
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