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I Some questions regarding the initial singularity

  1. Aug 7, 2016 #1
    I seem to have missed the opportunity to post my questions on a related thread so I hope this is okay.

    First, a request. I have read on this forum that ["Singularity" is just shorthand for "the place where the math model breaks down and we don't know WHAT is/was happening".].
    Since the wiki doesn't have a lot of info on this matter, are there any respected sources to back this claim up?

    I also have 2 questions:

    1)Does the Big Bang singularity require space-time or space/time to exist? Does it require anything at all to exist or can it be an independent entity on its own?

    2)Can it be said that the singularity is the Universe in another form? If so, can we say that the Universe is eternal? Do we have any reason to suspect( in the models that point towards a singularity) that the said singularity did not exist eternally into the past?
    I know the second question is not framed right since as far as I know in the models that have the initial singularity, time does not exist prior to the Big Bang expansion but I hope you get my point.
     
  2. jcsd
  3. Aug 7, 2016 #2

    PeterDonis

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    Sure, look at any cosmology textbook. Or look at any GR textbook; most of them discuss the application of GR to cosmology, which includes the "math model" you refer to here. But also, you should be aware that the math model which breaks down at the singularity is a highly idealized one that no cosmologist believes actually applies to our universe. See below.

    Both of which can only be answered for the highly idealized model I described above. Neither of them has any relevance for the actual cosmological models we use to describe our universe.

    The singularity is not part of spacetime at all, and does not "exist" in the sense that it is an actual "place" or "time" in spacetime. It's just an abstract limit that we can take as we go back in time in the idealized model; as that limit is approached, spacetime curvature in the model increases without bound. But the limit itself is not part of spacetime and does not "exist" even in the highly idealized model.

    No. See above.
     
  4. Aug 7, 2016 #3

    Chronos

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    That is a question that has perplexed scientists and philosophers for over 80 years. Truth is we do not have a complete unequivocal description of what constitutes a black hole singularity. Therein lies the problem - the question is too loosely framed to permit a cogent answer. Singularites laugh in the face of our very notions of physical reality. The answer 'The point at which our theories break down.' while true, is merely evasive. 'The point at which our fundamental notions of reality break down.' is a better answer, IMO. Concepts like time, space, matter and energy all seem to fall apart at a singularity. A good discussion of these issues is offered by Curiel and Bokulich here http://plato.stanford.edu/entries/spacetime-singularities/.
     
  5. Aug 7, 2016 #4
    I'm amazed at how little we actually know. Even with all of our advanced technology and knowledge, we're still relying on philosophy to answer our most basic questions. I guess that's really what I'm here for, is to try and figure out what we actually know, then try to put my worldview into that context.
     
  6. Aug 20, 2016 #5

    Chronos

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