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B How do we study space-time singularities?

  1. Nov 26, 2016 #1
    I hope I am posting this in the correct forum, I am trying to better understand space-time singularities. I can find easily the basic, and advanced information on what it is and the different theories. My main question is how do scientists study these space-time singularities?

    Thank you for your help.

    P
     
  2. jcsd
  3. Nov 26, 2016 #2

    phinds

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    You need to be more specific since "singularity" just means "the place where the math model breaks down and we don't know WHAT is going on". Which singularity do you have in mind? The singularity at the center of a black hole can't be "studied" in any empirical sense because it is causally removed from our universe and the Big Bang singularity is, as far as we are aware, unavailable for empirical study.
     
  4. Nov 26, 2016 #3
    I had a feeling I was being vague, excuse my ignorance. I was trying to understand a little bit more about black hole singularities, as well as the big bang singularity. Although I think you did answer my question, we cannot study these singularities, and it's "the place where the math model breaks down, and we don't know what is going on."

    If we cannot study these, why do scientists work on them and how do they quantify their research. If you can lead me to links for more reading that would be awesome.

    Thank you

    P
     
  5. Nov 26, 2016 #4
    The singularities arise as a prediction of GR in extreme circumstances (black holes, and a different kind of singularity for the big bang).
    Since it is impossible to observe what actually happens in these circumstances empirically, the only available approach is to mathematically extend upon GR, on the assumption that in these extreme circumstances it is not applicable, something else is going on.
    That doesn't mean GR is 'wrong' though, just that it is incomplete, it still describes spacetime perfectly for cases other than the extremes.
     
  6. Nov 26, 2016 #5

    phinds

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    I don't have any links to anything but I can tell you that the reason for examining the singluarity at the center of a black hole is because that's where GR and Quantum Mechanics don't play well together and we need a theory of quantum gravity.
     
  7. Nov 26, 2016 #6
    Thank you phinds and rootone, I appreciate your answer it definitely helped lead me in a more specific direction. If I have anything more to add so I am not vague I think I will come back to this thread.

    For now take care

    P
     
  8. Nov 27, 2016 #7
    I just had an idea, and I don't know what else to do with my ideas other than google them so I did. I Googled: Is what is after the observable universe a singularity because this is now what I have come to understand singularities as "the place where the math model breaks down and we don't know WHAT is going on" . The first link it brought me to was https://profmattstrassler.com/2014/03/21/did-the-universe-begin-with-a-singularity/. Did the universe begin with a singularity, which clearly does not remotely answer my question. As I began to type this I realize it has to be, in the definition of the math model breaks down and we don't have a clue of whats going on.

    So I stumbled upon this and perhaps this is what I was looking for with my first question, although I am not entirely sure: "So there were a number of attempts to get round the conclusion, that there was a singularity of infinite density in the past. "

    "The conclusion of this lecture is that the universe has not existed forever. Rather, the universe, and time itself, had a beginning in the Big Bang, about 15 billion years ago. The beginning of real time, would have been a singularity, at which the laws of physics would have broken down."

    http://www.hawking.org.uk/the-beginning-of-time.html

    And I can see how we would have no idea what is going on, but I would still like to know more. So the research continues.

    Thanks

    P
     
  9. Nov 27, 2016 #8
    I cannot edit, sorry I will preview before I post from now on.

    Googled: What is after the observable universe, a singularity? Because now I have come to understand singularities can be described as "the place where the math model breaks down and we don't know WHAT is going on" .
     
  10. Nov 27, 2016 #9
    What is expected to lie beyond the visible Universe is ...
    nothing spectacular,
    just more of the same kinds of galaxies in a similar distribution to those that are inside the observable sphere.
     
    Last edited: Nov 27, 2016
  11. Nov 27, 2016 #10

    phinds

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    The math model does NOT break down after the observable universe. As rootone said, it's just more of the same.
     
  12. Nov 27, 2016 #11
    Since you keep referring to a singularity: are you trying to ask what happens when the universe ends? If so, the theory before expansion was discovered to be accelerating was the big crunch, which ends in a singularity. The current theory is the universe will end in heat death, or thermodynamic equilibrium.

    https://en.m.wikipedia.org/wiki/Heat_death_of_the_universe
    https://en.m.wikipedia.org/wiki/Big_Crunch
     
  13. Nov 29, 2016 #12
    Hello Stoomart, no I wasn't trying to ask what happens when the universe ends. I am trying to do research of when the universe began, just like anything a study it seems like a bunch of rabbit holes. But I am glad you brought up the theory of what may happen when the universe ends, because after a few months of studying the begining I will be looking at the ending.

    Thank you for your reply

    p
     
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