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## Size of the Universe just after Big Bang

 Quote by Some Slacker Okay, we are at t=0 and the universe is a singularity? Yes? (if no, then I have no answer)
It is unknown what existed at the point in time that we define as t=0.
 Not to plunge back into darkness but... how long was the singularity around? Since t=0 must not have been there for long?
Actually the conditions prior to the Big Bang could have existed for any amount of time before inflation started.
 Yes? No? Doesn't really matter, my point here is that time (in our universe?) begins with a singularity, there is nothing else. To any observer from within the singularity the universe to me would still appear infinite (though very boring) as the singularity has no space, (or light, or matter or anything else) so if there were some way for you sense anything from within the singularity it would appear the same in all directions and go on forever, since nothing can escape the singularity anyway and there is nothing out there to see.
In addition to not knowing what happened at this point in time, there would NOT be any way to sense anything from within any said singularity. We cannot just say that we can and ask what happens. It is likely that if the singularity was real, there is absolutely no way for you or I to even imagine it, let alone attempt to describe it.
 So from the start I see the universe as infinite and then during inflation I would also see the universe as infinite since expansion is happening at faster than light speed after that the universe ends up as infinite because I want it to be (yes back to flippancy so shoot me). Infinity +/- 1 makes no sense so I'm stickin with infinite.
You would never see the universe as infinite, as there is a maximum speed limit in the universe, c. You can only see as far as the conditions allow. In our case today, we can see as far as 50ish billion light years in radius thanks to expansion. Anything beyond this is not observable due to the finite speed of light.

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 ...there would NOT be any way to sense anything from within any said singularity.
possible if you mean 'observe'...but Hawking-Hartle might disagree:

 .....the theory is a quantum gravity proposal concerning the state of the universe prior to the Planck epoch.... that there was no time before the Big Bang because time did not exist before the formation of spacetime associated with the Big Bang....that if we could travel backward in time ...... time gives way to space such that at first there is only space and no time.....
Hartle–Hawking state
http://en.wikipedia.org/wiki/Hartle%...3Hawking_state

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 Quote by Naty1 possible if you mean 'observe'...but Hawking-Hartle might disagree: Hartle–Hawking state http://en.wikipedia.org/wiki/Hartle%...3Hawking_state
I don't think they would disagree.