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B Before the Big Bang

  1. Aug 1, 2016 #1
    Hi all:smile:
    I have a question
    If now we can see objects from 13 billion years ago, what we'll see if the light will come to us more than 13 billion years, can we see what was before the Big Bang? Is that possible?
     
  2. jcsd
  3. Aug 1, 2016 #2

    phinds

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    No, that is not possible. FIrst of all, there are two meanings to "big bang". First, the "Big Bang Theory" which is a well confirmed description of the evolution of the universe from a dense hot state to what it is today. The Big Bang Theory says nothing at all about how the universe GOT to that hot dense state. There is no creation event in the theory. Second, the "Big Bang Singularity" which is a non-physical answer to the question of what do we get if we extrapolate the math model back to t=0. This is in some sense a "creation event" but it is not at all understood and is not part of the big bang theory.

    Now on to your question about light. We do not see all the way back to the beginning of the big bang theory's starting time. Google "Surface of Last Scattering" for more information.
     
  4. Aug 1, 2016 #3
    Why we can't see that? Maybe because our technology is not fully developed? Or light just can't come to us from impediments and long distance?
     
  5. Aug 1, 2016 #4

    Chronos

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    Due to Thompson scattering the plasma that comprised the post BB universe was opaque to photons, so theoretically we cannot detect photons emitted before the universe was about a few hundred thousand years old. This, of course, depends on the credibility of our plasma physics models. But, we have no cause to question that science at present. This is not to say all CMB photons we observe were released exactly at the same instant, but, it is to say they were all released over a very brief time interval compared to the age of the universe
     
  6. Aug 1, 2016 #5
    Thank you
     
  7. Aug 1, 2016 #6

    phinds

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    Why don't you google what I suggested you google. That would have answered your question.
     
  8. Aug 1, 2016 #7
    Yes thank you :)
     
  9. Aug 1, 2016 #8
    However, although we are unable to see light further back in time than the CMB,
    there have been reasonable proposals that with future technology it might be possible to detect neutrinos, other particles, and possibly gravity waves.
     
  10. Aug 1, 2016 #9

    phinds

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    True, but @Mary Space this does NOT mean we would be able to see to before the beginning of where the big bang theory starts. That is, we will not be able to see the creation event or whatever it was that was going on at t=0
     
  11. Aug 1, 2016 #10
    Yes, just further back than the CMB, it is not expected that an origin of the initial hot dense plasma will be discovered.
     
  12. Aug 1, 2016 #11

    Chronos

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    If hair splitting is your thing, it can be argued that the traditional big bang did not actually occur until after inflation. From the perspective of inflationary cosmology, conventional matter froze out of the inflaton field during reheating at the end of the inflationary epoch. The main point of this idea is it avoids the initial big bang singularity which confounds many people [including cosmologists]. Under this scenario, the scale factor of the observable universe assumes an initial finite value and the big bang model proceeds in an orderly fashion thereafter. This, of course, does not answer the question of what happens at t=0 prior to inflation, but, it removes the initial singularity from the BB by pushing it back to where it is more easily accepted we are clueless about what happened. If you run across the term hot big bang in the literature, this particular model is the one they have in mind. The motivation behind this idea is laid out here https://arxiv.org/abs/hep-th/9405187, Reheating after Inflation. And further explained here: http://arxiv.org/abs/astro-ph/9605155, The Origin of Matter in the Universe: Reheating after Inflation. The question now becomes "Can we see what happened before inflation?" Obviously, no.
     
  13. Aug 11, 2016 #12
    Since the universe ( everything ) was created from nothing in the big bang event, it is not really meaningful to talk of "before BB". Without matter or energy, time itself has no meaning and there can be no sense of 'before'.

    If this all sounds like a technical version of the creation event, that is because it was the idea of a Belgian priest who was also a professor of astronomy at a Belgian catholic university. One of his aims was to reconcile the church and science.

    https://en.wikipedia.org/wiki/Georges_Lemaître

    "In the beginning there was the word... " Christians say the word was God, scientists say the word was Bang.

    The expansion event is essentially : let there be light.
     
  14. Aug 11, 2016 #13
    This is not true, at least BBT doesn't say that.
     
  15. Aug 11, 2016 #14
    I'm sorry. Could you clarify what it does say. Just negating my statement does not enlighten us unless you can say what BB does say. Or are you just saying that it does not say anything?
     
  16. Aug 11, 2016 #15
    Did you even read this thread? :wink: From post #2:

     
  17. Aug 11, 2016 #16

    phinds

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    Weidoguy has it right, and I would add that the "creation event" is sometimes called the "Big Bang Singularity" (not part of the Big Bang Theory) with the word "singularity" meaning simply "the place where our math model breaks down and we don't know WHAT was going on".
     
  18. Aug 16, 2016 #17

    Ken G

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    Yes, we must distinguish between models that seem to break down, from physical descriptions of reality. A simple example of this kind of issue that is kind of the opposite of the "creation event" is if we had an expansion law that reaches infinity in a finite time. Any energy density that actually increases as the universe expands would do that, though it's hard to imagine what physical situation could give rise to that. But if we did observe such a model, we would be led to infer that the universe would reach infinite expansion in finite time. Then we would find ourselves asking, what happens after we reach the end of the expansion in a finite time? We would either have to conclude that time ends, or more likely, we would simply conclude that the model breaks down and the universe cannot expand infinitely in a finite time. After all, why would time have to end just because there's no longer any solution for the expansion? It's just the difference between a model and a physical expectation, and how the two differ when one leaves the realm of what can be tested.
     
  19. Aug 16, 2016 #18

    Andy Resnick

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    My preferred answer to the OP is "the question makes no sense: what is north of the north pole?'
     
  20. Aug 18, 2016 #19

    Ken G

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    I would say that depends on how highly we regard our understanding of the spacetime manifold in the ultra early stages of the Big Bang model. If we hold that our concept of the spacetime manifold should hold up at those stages, then your comment is spot on-- we have simply chosen a coordinatization of that manifold that gives no meaning to any time "before the beginning." And I suspect your position stresses the need to avoid a kind of personal prejudice, coming from our daily experiences, about time "marching on" in ways that have been found to be inconsistent with relativity theory. However, we can still note that a question does exist here, which could be framed as "do we really expect the spacetime manifold concept, and indeed relativity theory itself, to be able to be extended to the concept of a beginning of the universe?" That's a trickier question, especially given our difficulties with unifying relativity and quantum theory. So my preferred answer is "we don't have a theory that can inform the words in that question well enough to answer it", moreso than saying the question itself doesn't make sense. I guess it's an issue of whether or not we feel that we ask questions, and then use science to try to answer them, or if we feel that we must restrict our questions to those that our science has already given meaning to.
     
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