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B Does Universe have finite or infinite size?

  1. Mar 20, 2016 #1
    At the time of Big Bang the size of Universe equal the size of an atom.The Universe has expanded and the time from the Big Bang to the present is finite.Then at the present time the size of the Universe is finite or infinite?
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  3. Mar 20, 2016 #2


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    Not necessarily. If the universe is currently bounded (finite), it will have been very tiny at the time of the early Big Bang. But if it is currently unbounded (infinite) then it will have always been infinite - no matter how far we go back in time.

    At least, that's the implication of the currently accepted cosmological theories.

    Whether the universe is bounded or unbounded is unknown.
  4. Mar 20, 2016 #3
    Way less actually, but that's not the point, this is incorrect. The observable universe was smaller than an atom, it was just denser, the universe may be and always have been infinite.
  5. Mar 20, 2016 #4
    If universe always have been infinite,then how can we say about the beginning of space-time(therefore the beginning of time)?Is it because the gravity force very lage,so the space time was curved to zero?It seems there is contradictions:zero space-time but universe infinite?Are there two type of space-time:the space-time of observable universe that had the beginning and the space-time of whole unbounded universe(if universe is unbounded)?
    Last edited: Mar 20, 2016
  6. Mar 20, 2016 #5


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    Yes, it has one or the other, we just don't know which.
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