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A little thought of before the Big Bang

  1. Aug 16, 2009 #1
    I'm not exactly highly experienced, considering I'm only 17, but i was just curious what anybodies thoughts are regarding a little idea i had while reading a science fiction novel called A Signal Shattered

    My thought was that if before the Big Bang, the Universe was infinitely small and infinitely dense, has anybody ever wondered that maybe if one took the idea of alternate universes seriously, than maybe that infinitely small point of mass that becomes "our" universe is a... leak, for lack of a better term, of matter between "our" universe and another. And maybe that leak slowly built up, eventually exploding through, and that leak of matter is what makes up our universe.

    I know my idea lacks all the proper terminology, and it is probably thought of, but i don't really have a very valid source to give any kind of input on the thought, except for the internet of course...
     
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  3. Aug 17, 2009 #2

    Chalnoth

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    Well, one issue here is that there is no reason to believe that our region of the universe ever was infinitely dense. Granted, this is what our equations say when we take our known physical laws and extrapolate backwards in time, but this is just an indication that our equations aren't entirely accurate. Many think that a quantum theory of gravity will show us what happens when matter is really, really dense, and we won't get a singularity extrapolating backward in time (though it will obviously get really, really dense).

    As for the parallel universe part of the idea, yes and no. The issue with "parallel universes" is that you don't get matter leaking from one to another. Instead, matter itself is what defines these parallel universes. This idea is another way of talking about the many worlds interpretation of quantum mechanics, where we take seriously the wave function dynamics of quantum mechanics and throw away wave function collapse. What we find when we do this is that the appearance of wave function collapse happens anyway, as when the different components of a wavefunction interact with a larger system, the different components lose coherence with one another, preventing further interference, which makes it so that the different components after the interaction might as well exist in different universes.

    According to this, our whole universe is just one big wavefunction. Within that wavefunction are a large number of worlds. These are the parallel universes. So the matter that made up that original, extremely dense bit of matter didn't "leak" into other universes, rather it produced them as the matter interacted with itself and produced multiple, incoherent bits of its own wavefunction.
     
  4. Aug 17, 2009 #3

    Chronos

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    Observational evidence distinguishes science from science fiction. What we dont see is scientifically irrelevant.
     
  5. Aug 17, 2009 #4

    Chalnoth

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    Well, in a sense. But we can use our understanding of what we do see to place limits upon what we don't see.
     
  6. Aug 29, 2009 #5
    Time began when man invented it as a concept to usefully measure the passing of events and the measurement of events. Time can be ignored. Chain events happen and once they have that is that. We can put our clocks back an hour but it doesn't mean that the universe is younger, it is just our measure of orderly things. The universe and it's eventual extiction will take place at a point in the future and then something else will happen.
     
  7. Aug 29, 2009 #6

    marcus

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    I agree with Chalnoth about this. There is no question---the great part of what scientfic theories tell us is about stuff and events which we don't see.
    We test them by comparing what they predict about what we can see.
    We cannot peer inside every proton to check that it is made of three quarks. There might be some protons in which there are little Mickey Mouse dolls instead if quarks. But we use the theory because it predicts effects we can see.

    Likewise with the big bang cosmology, although we cannot see events before about 380,000 years of expansion, the model tells us about things in the first second, and we can check the model against other things that we can see.

    So it will be likewise with the models that go back before the big bang. They still need to be tested to show that they predict better than the original big bang model. We will still only actually see back to year 380,000, but when we have a model that goes back further than the present one, and predicts better, then it will become conventional in the same way.


    DJ there is currently a lot of research by reputable people into (eventually testable) models of cosmology that go back before the start of expansion. There are several main ideas, the dominant or most prevalent idea in current research is the bounce. A prior region of spacetime and matter (similar to ours in some basic respects) which collapses. And quantizing conventional general relativity/gravity theory leads to gravity being repellent at very high density---in some approaches---so at a certain very high density there is a bounce.
    There are also quantum gravity explanations of socalled "inflation"---a very rapid expansion episode that may have occurred.

    So in general yes people have wondered about a lot of ways it could have happened, a lot of mechanisms leading up to the big bang or start of expansion. I don't know if anyone has researched one that looks exactly like your idea. They have to be mathematical models that obey quantum mechanics and more or less imitate standard Gen Rel. It is hard to say whose research would match your idea as it is expressed in words.

    There is a lot of this kind of research going on. Steven Weinberg, a nobel laureate, is involved in it.

    Stephen Hawking used to be, back in the 1980s and 1990s but his ideas did not catch on and he has not been very active (especially with reaching retirement age etc.)

    Another prominent person, the Indian-born Abhay Ashtekar, is involved. Actually there is quite a list of major physicists getting into this "before the big bang" business.

    A popular book now selling pretty well on amazon, that deals with this, is called
    "Before the Big Bang", by Brian Clegg.
    I wouldnt necessarily want to buy it, or own it, but I plan to make sure my local public library has it on the shelf. It is the kind of thing not only a lot of scientists but a lot of everybody are curious about. Clegg sketches what some of the main theories say about conditions leading up to the start of expansion.
     
    Last edited: Aug 29, 2009
  8. Aug 29, 2009 #7
    I agree with you in respect to "theory" and "hypothesis". Nasa seems to agree us. :smile: We are in Physics Forums > Astronomy & Cosmology. :biggrin:

    Perhaps a review of an earlier topic that I contributed to might be helpful here too.
    https://www.physicsforums.com/showthread.php?t=331380
     
  9. Aug 29, 2009 #8
    “In the Big Bang theory the CMB Radiation is the relic radiation from the hot primeval fireball that began our observable universe about 13.7 billion years ago.” (Cosmic Microwave Background Radiation Anisotropies: their Discovery and Utilization, Nobel Lecture, December 8, 2006 by George F. Smoot iii, Lawrence Berkeley National Laboratory, Space Sciences Laboratory, Department of Physics, University of California. http://nobelprize.org/nobel_prizes/physics/laureates/2006/smoot_lecture.pdf)

    I love science and technology!:biggrin:
     
  10. Aug 30, 2009 #9

    Chronos

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    I did not mean to infer what we do not observe is scientifically irrelevant. I meant to point out it merely useful to refute irrelevant theories.
     
  11. Aug 30, 2009 #10

    marcus

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    Excellent quote from George Smoot!
    Does everybody understand the difference between the universe (which cosmologists model and study) and the observable subset of it? One learns to distinguish between the universe and the observable universe early on, e.g. in an intro cosmology course.
     
  12. Aug 30, 2009 #11
    Something potentially similar in respects, and postulated as one of many theoretical ideas and possibilities hat have grown from various aspects of String theories and particularly, Brane theories, is that our 'universe' (observable and beyond), that is, our 3 dimensions of space, were, prior to the Big Bang, compactified dimensions. These dimensions, through some interaction/reaction, were then "released" from their compatified state, and the cosmic expansion is the result of the "unravelling" of these dimensions.
    At least, it fits in with the notion of the expansion of cosmic structure.
     
  13. Aug 30, 2009 #12

    Chalnoth

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    Well, that's not quite it. Rather, the idea is that all of the dimensions were small and wrapped up. Then inflation happened. And when inflation happened, it only happened in three directions of all those available: those three dimensions didn't "unravel". They just expanded so dramatically that these small, wrapped up dimensions became absurdly large.
     
  14. Aug 31, 2009 #13
    OH, I see what you are attempting to do.

    I'm not sure as you state Chalnoth, "the idea is that all of the dimensions were small and wrapped up. Then inflation happened." That is an idea of yours, Chalnoth.

    “These concepts and ideas must pass muster – like a camel going through the eye of a needle – in agreeing with the multitude of precise observations and thereby yield an effective version of our now-working cosmological model. This is the key point of modern cosmology, which is fully flowering and truly exciting.” (George F Smoot, Lawrence Berkeley National Laboratory, CERN Courier, Jun 8, 2009. http://cerncourier.com/cws/article/cern/39163)

    George F. Smoot's statement ties in so very nicely with my last two messages.

    Let’s use this idea of mine taken from a plaque off my office wall, “When I dance, beautiful dreams begin to happen.” The last time I danced in high heels, I fell and injured my leg.:frown:Fortunately, my leg healed and I'm ready to dance again.:smile:
     
    Last edited: Aug 31, 2009
  15. Aug 31, 2009 #14

    Chalnoth

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    No, actually, it isn't. I was just attempting to clarify what this particular idea mentioned by _PJ_ was about.
     
  16. Sep 1, 2009 #15
    Let's take a look at what Chalnoth and JP wrote and compare it to an article from CERN about String Theory. It appears to me that String Theory has nothing to do with the established Big Bang Theory or inflation.

    I did find another article that peeked my interest. Perhaps others may like to read it.
    http://blog.case.edu/case-news/2008/10/13/blackholes

    I've contributed enough to this topic. Thanks for allowing me to share and learn. A valuable experience.
     
    Last edited: Sep 1, 2009
  17. Sep 2, 2009 #16
    Re post#6 and the "bounce" theory; if our universe is the result of an earlier universe that collapsed, then we must be expanding from a single point, a fact that is constantly denied on this forum. It also means that the earlier universe had first expanded in order to then collapse, which meant that the gravitational energy content was greater than the kinetic energy content that would have driven the expansion. Energy conservation laws state that our universe could only be driven by the same energy content. Slowing expansion, causing an increased rate of galaxy separation, and collapse are therefore inevitable. Doubtless mathematics will be able to prove this, although it is hardly necessary.
     
  18. Sep 2, 2009 #17

    marcus

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    Why so, Peter? If you actually go and read the quantum cosmology papers where the bounce is studied, they never show the prior phase collapsing to a single point. Quantum corrections to normal gravity take over before infinite density occurs and start the re-expansion. This happens both in the computer simulations and in the solvable analytical models.

    Expanding from a single point is exactly what does NOT happen in the bounce picture :biggrin:

    Again, why do you suppose this? If you look at the professional literature you see various cases, in some the prior phase only contracts and there is only one bounce event.
    In others there is an endless series of bounces. You seem to want to assume the latter but at present I don't think there is any reason to pick one over the other. In any event, the main thing is to verify (or falsify) and understand OUR bounce----see what observable features various models predict, look for them, test our ideas and equations about just this one brief episode in the early universe.

    If you want to take a look at the current research literature, here is a keyword search ("quantum cosmology") of papers since 2006, ranked by how often they get cited.
    Looking at the 50 top-ranking papers you will see that most focus on bounce models
    http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=FIND+DK+QUANTUM+COSMOLOGY+AND+DATE+%3E+2006&FORMAT=www&SEQUENCE=citecount%28d%29 [Broken]

    To see a brief summary of any paper just click where it says "abstract".
     
    Last edited by a moderator: May 4, 2017
  19. Sep 3, 2009 #18
    Obviously, I need to return to this topic. I'm going to stand behind my earlier messages from page 1. (It would be nice for new comers to review them.) Furthermore, I'm not aware of a "bounce" theory. I have searched extensively and have yet to find a "bounce theory" that will overturn the Big Bang Theory. (I will return later to another remark of Marcus on page 1 since no one has responded to it.) Nature and Science are internationally known peer-reviewed journals and I haven't noticed anything about the "bounce".

    Here is a small snippet from a larger article worthy of review that might be helpful.

    I highly recommend Math Pages! Please feel free to explore it and learn.
    http://www.mathpages.com/home/index.htm
     
    Last edited by a moderator: May 4, 2017
  20. Sep 3, 2009 #19
    I'm not sure how you could possibly distinguish between a bounce and an original expansion since everything is crushed down to quantum corrections which is what must have originally taken place.
     
  21. Sep 3, 2009 #20

    Chalnoth

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    That depends upon the type of bounce we're talking about. The only remotely-reasonable proposal I've heard to date is the ekpyrotic scenario, though I'm still a bit skeptical about that one. At least one nice thing about the ekpyrotic scenario is that it makes a very specific prediction: we shouldn't see what is known as B-mode polarization in the CMB. It can therefore be falsified by a positive detection of B-modes.
     
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