An embarrassing question: what were the boundaries of the universe

  • #1

Main Question or Discussion Point

I say always that the universe has expanded, from an initially-hot and dense state, until it get its current forme...
But it will be very natural to ask the question: at the first instances of its expansion, what were the boundaries of this universe, and what were the exterior of this boundaries..?
Can someone explain me this?
 

Answers and Replies

  • #2
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  • #3
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We're actually not sure if it's infinite or not (according to Marcus, and the FAQ, the current data fits both infinite and finite models, pretty much equally well), but:

-If the universe is infinite, then it was already infinite at the point of the Big Bang; there was never a time that it was finite.

-If the universe is finite, it still does not (and never did) have boundaries. What happens when you reach the edge of the universe? Well, you never reach an edge; try this and you'll only end up back where you started (rather like as if you tried to sail to the edge of the earth).

-In either case, it is expanding. One may wonder: if the infinite universe is true, how would an already infinite space expand further? Well, all the things in it just keep getting further away from each other.
 
  • #4
Thank you narrator and cephron, I think the idea is now somewhat more clear.
 

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