The Universe (part 2)

[BigDogsWang]

To continue on from Kermit's question: Can anyone put forward a theory of what is beyond 'expansion'. If the Universe can be likened to a balloon, then what currently is 'beyond' the balloon? Just empty space? If so, does it just go on forever?

It is my opinion that nothing can ever 'end', unless something just loops itself, i.e. could you travel so far in space that you would just end up back where you started?

Oh dear, I think my brain is beginning to melt......

[Loosehead]

You have to wipe your mind of normal concepts of space and time. The universe is not expanding "Into" anything, there is no outside, there is no after or before the universe just is, we cannot visualise it at all so we have crude attempts at comparisons with everyday objects like baloons but in reality we do not have any idea how to visualise 4 dimensions let alone the 11 for string Theory!

[Clanad]

...and, whether or not you would return to the starting point depends entirely on the 'shape' of the universe. Current theory describes the universe as essentially flat, in which case a return to the starting point would not be predicted.. If it is, alternatively, torodial or even saddle shaped, one could expect to return... so... it depends.
Loosehead could have added, perhaps, that the "balloon" carries with it the space you reference. Difficult mental picture to create or comprehend...