(January 19, 2010 at 2:44 pm)Purple Rabbit Wrote:That site mentioned the word "infinite" in the title and nowhere else. Could you point to some source that describes the idea properly? I can't see how in a finite amount of time you can go from no space and a singularity to an infinitely sized universe. Something doesn't make sense in the calculation...(January 19, 2010 at 1:55 pm)Tiberius Wrote: The explanation was why the universe isn't infinitely sized. If something is expanding, it can't be infinitely sized. That was all my point was about.An opportunity to disagree again!
As confirmed by the WMAP probe the universe is generally believed to be flat. Flat in the sense of a 2D analogon. If the universe is infinite, then it should appear flat. But with a flat universe there are still two possibilities, infinite or finite. This is hard to get your head round, I know. But something that is infinite can indeed expand. The expansion of space itself is not dependent on the finiteness of the universe.
There could be reasons why the universe appears flat and yet is not infinite. And of course, it could be that it appears flat because it is infinite. We have no definite proof.
Plus, every time a physicist hears the word "infinite" they cower. Someone once said that mathematicians handle infinities, but physicists simply can't, since it means their theories come falling apart. It's why singularities and black holes aren't well understood, because the equations involve physical infinities which can't exist according to other laws.
