Hi Tesla
I'll try an analogy for the following:
Is it not? space is a vacuum. it has to have an edge. have you ever seen a vacuum without containment?
The universe is expanding, is this not true? can it expand with no area for the expansion?
This is perhaps a poor analogy but the best I can think of and I hope Cavediver, Son Goku and any other theoretical physicist or cosmologist doesn't wince too hard if the comparison is poor - but...
Imagine a rubber balloon partly blown up. On its surface live two dimensional 'dots'. They have length and width but no height. Nor does the balloon they live on - it's a two dimensional universe they inhabit. The dots can slide around over the surface of the balloon but they can't go into the balloon's interior or come off its surface as that constitutes 'depth' - the third dimension which doesn't exist in their universe.
One dot says to another. "Where is the 'edge' of our universe?" After sliding over the balloon they find there is no 'edge' - they can slide over its surface indefinitely. But the surface is finite - no edges but a finite surface......hmmmm
Now lets have their universe expand. Let’s pump some air into that balloon. The rubber stretches and the dots move apart from each other (sound familiar - our galaxies are moving apart but it is space-time that is actually expanding - rather like the rubber fabric of our balloon instead of the actual galaxies moving).
"What's going on?" says our dots. They can see their universe is expanding - after all the dots are getting further apart and have to travel further to get back to each other for a conversation again....but into what are they expanding? Remember we as 3D creatures have the luxury of seeing their universe expand into the third dimension of depth that they do not have. They (as 2D creations) simply can't imagine what this third dimension could possibly look like - however their maths (if advanced enough) could predict it. The rubber of the balloon is a bit like your vacuum in your analogy - here it is finite and unbounded and 'held' in place only by the dimension unavailable to their perceptions. It makes no sense to the 2D men to say what is our world expanding into? - because that third dimension just doesn't mean anything to them!
Interestingly - they would be also able to deduce that their universe must in the past have been smaller if it is now expanding. No good looking for the point of expansion though - why? Well that point - if it started from a tiny balloon would be in the very centre of the balloon's sphere - which of course is in that third dimension of depth again. - I mention this because at least one creationist in a different debate once asked me to point to the heavens and show me where the centre of the big bang expansion was - as if to say "if you can't show it - it didn't happen!"
So - no edges but not necessarily infinite, vacuum that is not needed to be 'bounded', and expansion into dimensions that would screw our brains - except guys like Cavediver - seriously Tesla - people like these who have got theoretical physics degrees, post-doctorates, and spent decades in the field seriously know what they are talking about.....I'm just hoping he won't be too hard on this poor little analogy - I know it's basic beyond belief and probably wrong in a hundred ways - if so - I'm here to learn - are you??
Edited by Drosophilla, : No reason given.