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Inside the big bang were their other sub big bangs?

  1. May 19, 2015 #1
    As the question says. Sorry if it seems like a dum question!
  2. jcsd
  3. May 19, 2015 #2


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    The question does not make sense. What is "inside" the big bang, and what is "not inside"?
    What would a "sub big bang" be?

    The most likely answer is "no", but phrased like this the question does not make sense.
  4. May 19, 2015 #3
    Probably no.
  5. May 19, 2015 #4


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    There is no one unique consensus view as to how expansion got started, and what conditions preceded the start of expansion.

    So the words "big bang" do not have an established meaning---if you apply them to right at the start of expansion.

    Better you should say what YOU mean by a "big bang" before you ask the question.

    I don't ordinarily use that term because it's so vague as to be meaningless, but if I did I would give a reference to some professional research paper that describes one version of the start of expansion which is being studied. Like for example I might give a link to this, just to be specific:
    A ΛCDM bounce scenario
    Yi-Fu Cai, Edward Wilson-Ewing
    (Submitted on 9 Dec 2014)
    We study a contracting universe composed of cold dark matter and radiation, and with a positive cosmological constant. As is well known from standard cosmological perturbation theory, under the assumption of initial quantum vacuum fluctuations the Fourier modes of the comoving curvature perturbation that exit the (sound) Hubble radius in such a contracting universe at a time of matter-domination will be nearly scale-invariant. Furthermore, the modes that exit the (sound) Hubble radius when the effective equation of state is slightly negative due to the cosmological constant will have a slight red tilt, in agreement with observations. We assume that loop quantum cosmology captures the correct high-curvature dynamics of the space-time, and this ensures that the big-bang singularity is resolved and is replaced by a bounce. We calculate the evolution of the perturbations through the bounce and find that they remain nearly scale-invariant. We also show that the amplitude of the scalar perturbations in this cosmology depends on a combination of the sound speed of cold dark matter, the Hubble rate in the contracting branch at the time of equality of the energy densities of cold dark matter and radiation, and the curvature scale that the loop quantum cosmology bounce occurs at. Importantly, as this scenario predicts a positive running of the scalar index, observations can potentially differentiate between it and inflationary models. Finally, for a small sound speed of cold dark matter, this scenario predicts a small tensor-to-scalar ratio.
    14 pages, 8 figures.
  6. May 20, 2015 #5
    Okay, thankyou for your help. Apologies for the confusion of the question. I'm 15 and curious!
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