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If I say that the universe is finite, how can you say with certain that I am wrong?

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Have a look at answers to What is behind the cosmological horizon barrier?. – Warrick Mar 20 '12 at 13:28
First you have to define "universe" – TryTryAgain Mar 29 '12 at 22:42
Resisting the temptation to post a variant of this answer. – Keith Thompson Apr 2 '12 at 2:13

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Due to General Relativity the universe started 13.7GYr ago. It was finite then and since there was no phase of infinite expansion, it is still finite.

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Where is your proof that it was finite then? Current measurements of the curvature of space indicate that it's flat; and a flat universe has to be infinite. – Dan Neely Mar 21 '12 at 13:48
@DanNeely Was it flat back then too? – draks ... Mar 21 '12 at 14:14
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George Gamow tried to explain the origin of the Elements Georges Lemaître's theory of the expansion of the Universe. He proposed a ball of neutrons exploding as the Big Bang,nucleocosmogenesis. http://en.wikipedia.org/wiki/George_Gamow Alpher and Robert Herman predicted that the afterglow of the big bang would have cooled down after billions of years, filling the universe with a radiation 5 degrees above absolute zero. Alpher and Herman's prediction in support of the big bang was not substantiated until 1964, when Arno Penzias and Robert Wilson made the accidental discovery, for which they were awarded the Nobel Prize in Physics in 1978.The universe was once very hot and dense, and the photons and baryons formed a plasma. As the universe expanded and cooled, the radiation (photons) decoupled from the matter. The radiation cooled and is now at 2.73 Kelvin. http://aether.lbl.gov/cmb.html

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This is amazing conformation of the Big Bang & the finite nature of time & space. – Brian Goulet Mar 29 '12 at 18:06
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If the universe is infinite, there would be an infinite amount of stars in it, therefore there will be no night and we have to sleep in Sunglasses.

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not necessarily. the universe could be a fractal. en.m.wikipedia.org/wiki/Olbers'_paradox – Jus12 Apr 2 '12 at 13:35
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What you're describing is Olber's paradox. It requires the universe to be infinite in both volume and prior duration. A finite volume or a finite age will both render it null and void. en.wikipedia.org/wiki/Olbers%27_paradox – Dan Neely Apr 2 '12 at 17:35

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