Quote:
Originally Posted by skaltezon
I agree with your conclusion that the universe is finite because I don't believe in actual infinities. But it's an arbitrary choice.
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Quote:
Originally Posted by skaltezon
Infinities are interesting because no one has ever seen one. I don't think anyone can describe the consequences of an infinite anything, because we don't know what the rules are. Your intuitive sense that something without limits can't possibly get any larger seems reasonable, though.
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I imagine that the universe always existed as an infinite space that nevertheless can expand.
When the Big Bang is described as the event during which the cosmos went through a superfast "inflation," expanding from the size of an atom to the size of a grapefruit in a tiny fraction of a second (as shown in Jackhammer's original post:
http://ssscott.tripod.com/bang.jpg), I imagine the universe as having consisted of an infinite space full of those tiny atom-sized areas expanding.
The universe would then be an infinite space where expansion occurs at every point within that space.
If the universe at the time of the Big Bang was an infinite space of dense matter and expanded at every point within that space, then we would have something without limits that expands yet isn't actually getting "larger" because the space was infinite to begin with. When I write that, it sounds contradictory, but for some reason it doesn't bother my intuitive sense!
Since the expansion of the observable universe occurs faster than the speed of light, and thus prevents us from seeing beyond the cosmological horizon (beyond which light heading in our direction will never get to us, since space is expanding faster than light travels), we are doomed to never know what is beyond the observable universe (
Observable universe - Wikipedia, the free encyclopedia).
Nevertheless, I imagine the unobservable areas of our universe as being fundamentally the same as what we can see because I have no reason to think they would be different. If the current universe is infinite, then it makes sense to me that the universe at the time of the Big Bang was infinite, as well, and able to expand.
Quote:
Originally Posted by tore
According to the The Big Bang theory, our universe started with a "big bang" (or rapid expansion rather), but predicting what happened before that when you have all the matter of the universe in one place is not really simple.
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Did our universe really *start* with a Big Bang? I didn't think there was any evidence for a lack of matter and energy before the Big Bang.