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Big Bang : Singularity or Singularities?

  1. Aug 22, 2014 #1
    The Big Bang is often associated with the concept of a singularity. A singularity is defined as a point in space-time. A common interpretation is that the concept of a point is meant to capture the notion of a unique location in an Euclidean space. This seems to me very misleading in as much that:
    1) At the moment of the singularity there was no space-time and consequently no unique location in an Euclidean space.
    2)To my opinion, a singularity also leads to the common misinterpretation that the Big Bang occurred somewhere ( anywhere you like) in an already existing space as a unique event in an already existing time.
    Would it not be more enlightening to talk about Big BangS and singularitieS ? I mean that every observer, wherever in the universe, could be a singularity on its own and the center of its own Big Bang. Could it be that there are as many singularities and as many "experienced" Big Bangs as there are observers in the entire universe?
    Quite controversial I know, but can anyone explain why this approach is potentially impossible?
    Many Thanks, Jozsef
     
  2. jcsd
  3. Aug 22, 2014 #2

    Simon Bridge

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    A singularity is a mathematical construct that may have any geometric distribution or none.

    In GR, a singularity a result of a "geodesically incomplete" spacetime.
    eg. a Kerr black hole has a gravitational singularity in the shape of a torus.
    http://www.math.ucla.edu/~bon/kerroview.html [Broken]

    A singularity may be a point, but it does not have to be.
    The singularity postulated at the big-bang being an example.
    i.e. the big bang is something that happens everywhere.

    The thing that leads people to think of the big bang as having occurred someplace in space is the name "big bang". It's suggestive of an explosion - people have seen explosions on TV, they all start out at some concentrated volume in space.
    http://www.livescience.com/32278-was-the-big-bang-really-an-explosion.html

    That just multiplies the problems and falls foul of Occams razor. The only need for this was if you thought that singularities had to be points.
     
    Last edited by a moderator: May 6, 2017
  4. Aug 22, 2014 #3

    jedishrfu

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    I think the problem here is that you are embedding the Big Bang into a geometric framework whereas our theories stop at the Big Bang event and can't proceed any further into the past before the event.

    http://en.wikipedia.org/wiki/Big_bang

    The view is that for us spacetime was created at the instant of the Big Bang.
     
  5. Aug 22, 2014 #4

    marcus

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    The word "singularity" came into use in math over a hundred years ago, and was never intended to suggest a single point.

    Back in the 1800s it meant "strangeness" "oddity" "weirdness".

    Taken over into math it referred a breakdown or blowup in a mathematical theory, where some formula stopped giving reasonable numbers, or an equation stopped being solvable.

    The word doesn't normally refer to anything in nature, or that really happens. It means failure or glitch in some man-made theory.

    The popular media have misled the public into thinking that "singularity" refers to something real in nature which existed at a single point :biggrin:

    Basically it is a problem in GR-based cosmology that people are working on getting rid of.
    for a popular outreach essay about this from Einstein Institute, google "tale of two big bangs"
     
  6. Aug 23, 2014 #5
    Thank you Marcus, this is very clear to me, Jozsef
     
  7. Sep 6, 2014 #6
    First of all, the name of this particular singularity is “the cosmological singularity” (unfortunately popular resources such as Wikipedia do not emphasise distinction between “a singularity” as a common noun, and this concrete thing; not such great minds as R. Penrose write these). Also, the cosmological singularity is the most obvious conjecture to explain the Big Bang, and the best theoretically substantiated, but not the only possible.

    It is correct that, if the cosmological singularity existed, then it would be a misconception to think about it as about one point. From conformal point of view, it is a 3-dimensional space-like manifold forming a boundary of our universe (Ī once made this calculation, but didn’t publish it anywhere, although IMHO there are already many publications about it). One or many is a purely terminological quibble; Ī prefer to think about the singularity because there were no several discrete singularities.
     
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