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B The big bang singularity and black hole singularity

  1. Jul 18, 2016 #1


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    In the big bang model the singularity is all ways quoted as being the start of the universe, but AFAIK scientists do not accept the singularity as real, the same with the black hole singularity, what is proposed to be in their place?

    from Wiki.
    The initial singularity was the gravitational singularity of infinite density thought to have contained all of the mass and spacetime of the Universe[1] before quantum fluctuations caused it to rapidly expand in the Big Bang and subsequent inflation, creating the present-day Universe.[2] The initial singularity is part of the Planck epoch, the earliest period of time in the history of the universe


    In the centre of a black hole is a gravitational singularity, a one-dimensional point which contains a huge mass in an infinitely small space, where density and gravity become infinite and space-timecurves infinitely, and where the laws of physics as we know them cease to operate. As the eminent American physicist Kip Thorne describes it, it is "the point where all laws of physics break down"

    Here they talk of a one dimensional point is that even possible?
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  3. Jul 18, 2016 #2


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    There are multiple ideas.

    With inflation, it's often proposed that there was an initial quantum fluctuation in the finite past which kicked off inflation. This initial quantum fluctuation would have selected a value of the inflaton field that was high enough in energy over a finite region to start off inflation. With this model, it's not possible to simply extrapolate backward in time to find this initial state.

    With loop quantum cosmology, there was a previous collapsing universe which, once it became sufficiently dense, bounced back and started expanding again. No singularity is reached during the bounce.
  4. Jul 18, 2016 #3


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    On the question of the blavk hole singularity what do they mean by a one dimensional point is that even possible?
  5. Jul 18, 2016 #4


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    It means it has no physical size. It's one-dimensional in the sense that it still extends through time, but has no spatial dimensions at all.

    No, I'm pretty sure that it's not possible. It's essentially dividing by zero.
  6. Jul 18, 2016 #5


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    The rough translation of "a one dimensional point" is "I have no idea what I'm talking about so I'm just going to say things".
  7. Jul 18, 2016 #6


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    No, it isn't. If we are going to try to describe the singularity in these terms, it's a spacelike line, not a point. This is assuming we're talking about a Schwarzschild black hole (i.e., not rotating or charged).

    The black hole singularity in Schwarzschild spacetime is spacelike, not timelike. It should be thought of as a moment of time, not a place in space.
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