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The Shape of the Universe

  1. Jun 20, 2011 #1
    I'm a college student in New York and I've been doing some thinking lately. Although mathematics is unfortunately one of my weaker subjects, I was wondering what you all might think of this idea. I've been reading about black holes and looking at different ideas of what the universe may look like. But none I've found posit that they may look like an exploding supernova (e.g. sn1987a). If the Big Bang theory is accurate, then could it be that the energy that propelled the Universe into being was similar to what happens when a star dies and becomes a black hole? The outer rings of the supernova match the toroidal model of the universe, but maybe we are just in that outer ring and if so, there should be another ring opposite the point of singularity. In this instance, there could be other events like this occurring beyond the limit of our "Universe". Maybe our exploding 'giganto-super star' that formed these outer rings is just one of many other giganto-super stars in what is truly a universe beyond the scope of our imagination.
    My knowledge of physics is very limited, and this question arises out of limited observations of other cosmological events.
    Another question: In the documentary A Brief History of Time, Stephen Hawking explains that black holes do give off a form of radiation. Is it possible that the point of singularity has a maximum potential for the matter it can absorb? If so, would it eventually reach a critical level and reform a new star?
    Thanks for your time
  2. jcsd
  3. Jun 20, 2011 #2


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    I think the difficulty here comes from your analogy between the BB and a real, physical explosion. You should not think of the BB as an explosion at all, but rather as merely a rapid period of expansion of spacetime itself. There are a billion threads here explaining why you cannot think of the BB as expanding 'into' anything, but I think that's the crux of the issue here.
    Black holes do indeed emit radiation, aptly named Hawking Radiation. The power of this radiation is actually inversely proportional to mass though, so as a black hole absorbs more matter it actually radiates slower. So there is no maximum size for a black hole. You could perhaps suggest a minimal size, smaller than which the black hole would evaporate in shorter than a planck time, as which point it doesn't make much sense to talk about it existing at all.

    So no, a black hole will never form a new star.
  4. Jun 20, 2011 #3
    Wow. Thank you for making that very clear and understandable. Do you know where I might find different models and theories of the shape of the universe?
    Also, is it true that the math backing up these theories falters when it nears the beginning of space and time? What does that suggest?
  5. Jun 20, 2011 #4


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    The friedmann models are probably the most common and least complicated of all universe models: http://www.phys-astro.sonoma.edu/people/faculty/tenn/FriedmannModels.html [Broken] and http://en.wikipedia.org/wiki/Shape_of_the_Universe (only ones I could find without the math at this moment). I wouldn't say the math falters but rather GR falters when it encounters naked singularities such as the big bang (the only naked singularity we know of). It suggests that we need a quantum theory of gravity in order to actually study the universe directly after the big bang.
    Last edited by a moderator: May 5, 2017
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