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Before big bang

  1. Jul 11, 2003 #1
    What do you guys think existed before the big bang... since it is the leading theory on the birth of the universe.. what do you think existed before?? nothing? and what is the leading theory on what actually caused the big bang to occur??
     
  2. jcsd
  3. Jul 11, 2003 #2
    Marsh Mallow!
     
  4. Jul 11, 2003 #3

    marcus

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    You are asking about our personal beliefs.

    I see nothing wrong with assuming that the universe was
    always here

    It simply went thru a transition that Martin Bojowald
    and Abhay Ashtekar have been studying, some 14 billion years ago.

    They are modeling what has been called (using an inadequate theory) the "big bang" but in a way that goes continuously back in time and thru what used to be called the "singularity" because
    of a divergence in the old model.

    I see no reason that their effort, with the help of others, cannot succeed. So I assume the universe has always been here doing its thing according to whatever are its real equations
     
  5. Jul 11, 2003 #4

    marcus

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    "Existed before" is extra baggage.

    It is an unnecessary idea.

    Let us not clutter things up with assumptions and concepts we dont need.

    The universe (apparently in a contracting mode) existed before the era of rapid expansion which is still called the big bang but which may be called by other names once we have better equations to describe it
     
  6. Jul 11, 2003 #5
    Here's my weird personal beliefs!

    I think at the very bottom of stuff, all there really is to the Universe is geometry and motion (or maybe acceleration). No particles, no energy. Just geometry and motion.

    That dimensions of this geometry are discrete, but continuous, i.e., somehow the top order dimension folds back into the low order dimension. Calling them "top order" and "low order" is a kind of a misnomer though .. they all (can) have equal footing.

    And what we know as the Universe is just an expansion of three (or more) dimensions in a region that has more dimensions than what our Universe has. Nothing special -- it happens all the time. Kinda like the Multiverse, but a bit different.
     
  7. Jul 11, 2003 #6
    Re: Re: before big bang

    it isn't an unnecessary idea...

    if it contracted before it expanded... then something was there when it contracted.. so what about before that.... your belief then would be that time in infinite and has always existed... correct?
     
  8. Jul 11, 2003 #7

    marcus

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    "the leading theory" about what caused BB

    Always interesting to keep track of what the leading authorities in a field use as working assumptions

    Charles Lineweaver is on the short list of world's top cosmologists
    and was one of those in charge of the COBE microwave background mapping in the 1990s

    He has a recent survey of cosmology online (May 2003) called
    Inflation and the Cosmic Microwave Background

    www.arxiv.org/astro-ph/0305179

    a lot of really fascinating stuff about the latest model of the universe

    there are other good recent papers too but this says a lot in its 34 pages
    and as for the BB, he quotes Alan Guth (one of a handful of people that first developed Inflation scenarios). Here is what Guth said in 1997 in his book "The Inflationary Universe":

    <<...the standard big bang theory says nothing about what banged, why it banged, or what happened before it banged. The inflationary universe is a theory of the "bang" of the big bang.>>

    Which is not to say that Guth or anybody else can explain inflation. Not only are the experts ignorant about conditions before time-zero (although people are beginning to construct models of it), but there is no one clear picture of the early inflationary era. Despite the impression one might get from Guth's quote, inflation itself is not thoroughly understood---there are different pictures and no obvious way to choose between them.

    But Lineweaver has a diagram that gives some idea of the range of variation among the various pictures of inflation (figure 2)----and the subsequent reheating that gave rise to quarks etc. (figure 6)

    About time zero (the beginnig of the expansion phase we are in now) a good paper is

    www.arxiv.org/math-ph/0202008

    Ashtekar, "Quantum Geometry in Action..."

    It describes recent (since 2001) work by Bojowald and others showing that the scale factor of the universe----usually written a(t)----is quantized (a bit like the energy levels of a hydrogen atom) and the curvature 1/a2 is bounded at time zero.
    In GR and the Friedman equations derived from it, a(0) = 0 and
    the reciprocal goes to infinity----not considered physical and taken as a sign the theory fails. But in the quantum version of the same equations this divergence does not happen, no failure at time zero. Ashtekar gives an informal overview of this new development.
     
  9. Jul 11, 2003 #8

    marcus

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    Re: Re: Re: before big bang

    Correct.

    To me space looks infinite in all directions and I dont see any need to imagine a boundary

    to me time looks infinite in both directions so I dont feel
    any need to put limits on it

    If you think there is some reason, tell me. I am certainly willing to change my mind.

    A year ago I thought time must have a beginning some 14 billion years ago, but I couldn't imagine how that could happen.

    But since I read the recent quantum cosmology papers esp by a young postdoc of Ashtekar's named Bojowald it has occurred to me that there is no reason to suppose that time has a beginning.

    Or that space, which is infinite and able to expand, has any beginning or limit.

    These limits are additional complications which I now do not see any need for

    In fact I have begun to suspect that people have always been drawn to images of a beginning and an end of time because of their dramatic effect.

    Because our own existence is bounded by birth and death these ideas attract us like magnets and polarize our imagination. We are suckers for the ideas of the beginning and the end.

    But scientifically speaking these are not compelling ideas.
     
  10. Jul 11, 2003 #9
    Re: Re: Re: Re: before big bang

    I completely agree. Science cannot reconcile the concept of creation ex nihilo except through hypothetical, non-causal, mathematical abstractions.
     
    Last edited by a moderator: Jul 11, 2003
  11. Jul 11, 2003 #10
    marcus,

    Thanks for the links on those papers (and i find out somebody else has swiped my quantum fluctuation/inflation/galaxy seed idea ;) ).

    The author talked about the "reheating" phase that occurred after Inflation, when matter was created. Do you know if this phase is supposed to the the same as the Sakarov matter/antimatter annihilation phase, or if they occurred at the same time?

    What I'm really asking (and I've "Asked the Experts" this, with no clear answer), is when in relation to Inflation did the matter/antimatter annihilation phase occur?
     
  12. Jul 11, 2003 #11
    I'm coming into this a little late, but since you asked for something that is now just a matter of belief, here goes:

    I have the very highest regard for Marcus (an excellent thinker), but I have to register a mild disagreement: If we can expand knowledge notebly back "beyond" Planck's Constant, then we may learn a little bit more about the Big Bang (and every little bit helps).

    The cosmic background has been found (probably) to be just a very little bit anisotropic. Further study on this may lead us back before the advent of Planck Time.

    Now, we may be essentially no more closer to the real than we were before. (We may ultimately end up just seeing "soup.")

    How can we gain this further evidence? I don't have a clue, even though I've been thinking about this for a long time.

    We already have conjecture about things before wave/particle origin, but peeking through the "keyhole" of cosmic anisotropy? Who Knows?
    That may turn out to be as helpful as the quantum has been.

    I believe that our Universe began as a result of the little bit of "dysharmony" in waves/particles (or whatever) that resulted from a collapse of a preceeding Universe.

    There's no way I can offer any concrete evidence for this view; but Thank God (so to speak) I don't have to defend it in the context of this thread.

    Thanks, Rudi
     
    Last edited by a moderator: Jul 12, 2003
  13. Jul 12, 2003 #12

    marcus

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    reply to r637h and Nacho

    r637h thanks for the kind words, I just found both your posts and will try to respond tho without any special insight I'm afraid, or expertise on these questions
    Nacho, PF may actually be a good place to get such questions answered! Just start a special thread about a particular question
    (like "what happens in the 'reheating phase' after inflation?") What can you lose? Some quite knowledgeable people post
    at PF on occasion and they might answer. Or if not, and you get
    only speculation and/or humor, what harm is done?

    Now I am tempted to start such a question thread, being curious myself about what people think concerning inflation.

    If one goes by Lineweaver's Figure 6, the answer to your question would, I expect, be negative because he shows
    reheating bringing temp back up to E22 eV which is too hot
    for quarks. In his picture quarks start to exist at the much
    cooler temp of E16 eV. So I would guess and say "no" the
    shakeout in which most of the matter and antimatter annihilated
    leaving a residue of matter (Sakarov?) must have happened WAY later than this imagined "reheating" is supposed to have occurred. I dont think the experts have a sure idea of when or for how long or at what exact temperature inflation occurred.

    Just because we think maybe the experts do not have it together yet on inflation doesnt mean we cant ask! I strongly favor asking even tho realizing that the answers may still be very unsatisfactory.

    I will write a second post about inflation----why it is hypothesized, to solve what problems (the flatness problem, the horizon problem, the expansion problem, the structure problem).
    Inflation is currently compelling because it responds to these especially to "how did the U get to be so flat" and "why is the CMB temp nearly the same in all directions?"(horizon problem).
    It could be that another picture of time zero will emerge which will
    also respond to the flatness and horizon problems. This would
    have an interesting effect on people's assumptions about inflation.
    -------------------------------

    Rudi your post is extremely interesting. The idea of the CMB anisotropy as a "keyhole" that one can peer thru to see conditions very near or even before time zero rings true. Just the right metaphor. also this is a great idea:
    <<I believe that our Universe began as a result of the little bit of "dysharmony" in waves/particles (or whatever) that resulted from a collapse of a preceeding Universe.>>
    I want to simply recopy your post, kind words deleted out of modesty, and think about it:

    <<....
    If we can expand knowledge notebly back "beyond" Planck's Constant, then we may learn a little bit more about the Big Bang (and every little bit helps).

    The cosmic background has been found (probably) to be just a very little bit anisotropic. Further study on this may lead us back before the advent of Planck Time.

    Now, we may be essentially no more closer to the real than we were before. (We may ultimately end up just seeing "soup.")

    How can we gain this further evidence? I don't have a clue, even though I've been thinking about this for a long time.

    We already have conjecture about things before wave/particle origin, but peeking through the "keyhole" of cosmic anisotropy? Who Knows? That may turn out to be as helpful as the quantum has been.

    I believe that our Universe began as a result of the little bit of "dysharmony" in waves/particles (or whatever) that resulted from a collapse of a preceeding Universe.

    There's no way I can offer any concrete evidence for this view; ...>>

    YES! one should keep one's powder dry and not get overcommitted to some current expert view of time zero because there really are alternative pictures of time zero waiting in the wings.

    To me, it is very suggestive that people at Penn State (Bojowald etc) recently found that using quantum geometry to model time zero makes the singularity go away, so one has a collapsing cosmos leading up to time zero. For me, this is no harder to swallow than inflation----maybe easier.
    If something collapsed prior to time zero then maybe IT can help
    to understand the horizon (nearly uniform temp) problem or where the short-lived high value of the cosmological constant (the "scalar field" assumed to have caused inflation) came from.
    Maybe having something prior could simplify the intellectual landscape for the experts and clear things up a bit.

    whole process of human's trying to understand time zero is fascinating. I hope they do decide there is a "preceding universe"
    as you suggest that we can maybe even glimpse thru the
    anisotropy keyhole. These ideas are better than coffee this morning!
     
  14. Jul 13, 2003 #13
    Mainly to Marcus:

    And Thank You, sir, for your kind words.

    It goes without saying: There are formidable problems in trying to look back beyond Planck Time:

    1] Adequate data on the anisotropy of the CBR has not yet been gathered (but I'm confident that it will be).

    2] I have no confidence in the ability of Differential Topology or the comparison of derived manifold models to analyze the above. There has to be some other way.

    3] I also have a mistrust for M-Theory at the moment: Granted, various components of M-Theory give very adequate explanation for many cosmic phenomena... but how are the components related? I feel that M-Theory is Based on solid foundations, but I believe it has to undergo a period of "de-bunking" and simplification. (Not a problem: hypotheses and theories have always had to be modified in the light of new interpretations and observations.)

    Finally, the Physics community has a habit of launching off onto watseful tangents on occasion. Fortunately, there seems to be a lot of ability at work, however; and we'll get productive, meaningful answers, by-and-by.

    Thanks, Rudi

    PS: Thanks for the references to Ashtekar and Bojowald. Interesting and thought-provoking (even though I don't understand their reasoning in some respects). The biggest problem is that the people at Penn State are all a bunch of morons. (Just kidding!)
     
    Last edited by a moderator: Jul 13, 2003
  15. Jul 13, 2003 #14

    marcus

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    Well of course they are! The fact is wellknown at all the surrounding colleges and universities!

    I have also heard from reliable sources at the University of California that the people at Stanford are all morons too. And so, to my considerable satisfaction, I have come to believe this to be a general condition at institutions of higher learning. :wink:
     
  16. Jul 13, 2003 #15
    There is no more effective set of blinders than a rigorous set of immutable preconceptions.
     
  17. Jul 13, 2003 #16
    I think that before the BB, there were membranes of the universe, waiting for a force to make them collide.
     
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