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Before the Bang

  1. Dec 7, 2007 #1
    Where did everything that went 'bang' come from ? It would seem to me that even potential must have a source of origin. Accepting that the Big Bang is true, where did it come from ? Where did all the potential of the unified field come from that went 'bang'? What caused all the 'matter' of the known universe to come into existence to go 'bang' in the first place? How do you make something out of nothing to go 'bang' ? thanks, hg
     
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  3. Dec 7, 2007 #2

    Chris Hillman

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    Hi, hubertg, welcome to PF!

    I think you will find this FAQ from Ned Wright (Astronomy, UCLA) to be very informative and insightful.
     
  4. Dec 7, 2007 #3

    marcus

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    Hubert this question cannot be answered authoritatively. There are professionals who study this and construct models of the early universe. In some of the models there is no singularity (no point where the model fails and stops computing) and time evolution can be explored on back before the onset of expansion. In some models, there is a singularity: the model blows up at a certain point as you go back and fails to give meaningful numbers.

    Since no one model has been favored by observation---modeling the universe before the beginning of expansion is a fairly new area of research---no one can tell you what to think. You can sample the various ideas, or make up your own. But if you are interested, I will give you a sketch of where I think the field is going based on the latest international conference.

    The last big international conference of general relativity and cosmology people was July 2007 in Sydney Australia. Called GR18 (the 18th conference of the International Society for GR). 600 people, from many GR and cosmology-related specialties attendend.

    It is noteworthy that at this conference 2 loop quantum cosmology people were honored.
    Abhay Ashtekar was elected president of the ISGR, which holds the conference. Martin Bojowald was awarded the Xanthopolous prize. Bojowald also conducted 2 workshops ----one on quantum big bang models and one on quantum black hole models. An interesting feature of quantum models is that the singularities (breakdowns) experienced in the earlier "classical" models can be avoided. This is the kind of research that Ashtekar and Bojowald, with their co-workers, are currently engaged in.

    In case you want to glance at the American Physical Society newsletter I got this from here's the link
    http://arxiv.org/abs/0709.0942
    The APS has a group of researchers focused on gravity matters (GR, cosmology...) and here's part of their report.

    GR18/Amaldi 7 in Sydney 2007
    Jorge Pullin, Louisiana State University

    The 18th International Conference on General Relativity and Gravitation (GR18) and the
    7th Edoardo Amaldi Conference on Gravitational Waves were held concurrently in Sydney, Australia, July 8-14 2007. Over 600 scientists converged on the Sydney Convention and Exhibition Center at spectacular Darling Harbour. There were 15 plenary talks and 55 parallel sessions. A typical day had one “Amaldi” and two “GR” plenary talks and there were five “GR” and only one “Amaldi” parallel sessions in the afternoon. The format was a bit of a departure from the tradition of Amaldis, where in the past there was no division between plenaries and parallels.

    During the conference the Committee of the International Society of General Relativity met. Among other topics, the results for the election of the president of the society were announced, Abhay Ashtekar was elected.
    ...
    The Basilis Xanthopoulos prize was presented jointly to Martin Bojowald (PennState) and Thomas Thiemann (Albert Einstein Institute) for their seminal contributions in loop quantum gravity.


    I guess my point is that if you want to know "what was before the big bang?" and you want to know what the work of Ashtekar and Bojowald (and 20 or so others) says about it then its very easy! There is no problem because there is no singularity where the model blows up----it just probes back in time and finds a contracting phase, which contracted to a high (but finite) density and turned around and began re-expanding.

    And these are prominent respected experts in the field of early universe cosmology. Their work is increasingly recognized. They publish in top peer-review journals (Physcial Review Letters, Physical Review D, Nature Physics, ...) and their work is highly cited by other researchers. Their work and that of immediate collaborators, in past 5 years, ranks the highest in citations of all quantum cosmologists. But you don't have to believe their results!

    That's important to recognize. There is no authority structure here telling non-specialists and laymen what they should believe. There are half a dozen different pre-big-bang scenarios. You can google around, find various ones that appeal to you, and choose what you like. Or you can be completely skeptical and believe nothing until more evidence has accumulated---take a wait and see.

    All I want to get across is that you don't have to accept what someone like Stephen Hawking says. You can poke around in the professional early-universe research field and find out who are some prominent respected people and find out what they are talking about these days among themselves. That is, at some major gathering like GR18 conference.

    Stay tuned, it is a fast developing field and there will almost certainly be significant developments in the next 6 months.
    You won't find popularized accounts of current early universe quantum cosmology research. But if you want to look at a sample of the professional journal articles, here is a recent one of Ashtekar.
    http://arxiv.org/abs/0710.3565
    This page gives the summary, click on PDF over on the left to see the whole thing. The Intro and Conclusions sections at the beginning and end are usually more accessible in this kind of article. If you are curious enough you will get something out of it.
     
    Last edited: Dec 7, 2007
  5. Dec 8, 2007 #4

    Chronos

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    A well intended answer, marcus, but inconsistent with the level of the question. The universe either sprang from 'nothing' [see Sean Carroll's 'A Universe from Nothing'], or sprang from a preexisting state of something that appeared to be nothing [see Lee Smolins cosmological natural selection]. Neither answer is entirely satisfactory, IMO. We can, generally speaking, agree it does exist and has measurable properties.
     
  6. Dec 8, 2007 #5

    marcus

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    It's often hard to know the technical level that's right. In this case it doesn't seem to have been inconsistent though. I was very happy with hubertg's reply (he wrote back PM) and felt we connected OK.

    Part of the bewilderment some people experience may actually be traceable to words like "the universe sprang", which makes it seem as if some moment (presumed to be some 13.7 billion years ago) is special. It doesn't have to have sprung or arisen from anything----it can simply have continued existing.

    If you are using a model which doesnt happen to break down at that point, then time just continues on back prior to that point. You still have no idea where the universe came from, but there is no designated instant when it "arose".

    I believe the reason we have the illusion there was some moment 13-odd billion years back when the universe "arose" is simply because the OLD model that has been in use for decades happened to break down at that point.

    For over 50 years we were using a model (almost exclusively) in which temporal evolution broke down and this somehow kind of sanctified the point where the model blew up. But models don't have to blow up there, we now know. So there is no need to be mysterious about it.

    For the time being you can take your choice. If you like a model that blows up you can stick with the old Friedmann-LeMaitre (circa 1920). If you like a model that doesnt blow up, you have several choices including what Ashtekar and others are using for their computer models. (and then there is no point at which "the universe arose").
     
    Last edited: Dec 8, 2007
  7. Dec 9, 2007 #6

    Chronos

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    I'm glad you and hubertg connected, marcus. It looked like a pedagogical question to me.
     
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