[everyone]

If you inflate a balloon, the surface area of the balloon increases and some dots drawn on the surface would get further apart but you couldnt say that the enlargement has a 'centre' The entire surface is simply expanding everywhere at once. The universe is like that with an extra dimension.

[ttctciyf]

So, unlike God[1], the Universe's circumference is everywhere, and its center nowhere? :)

[1] http://bottlerocketscience.blogspot.co.uk/2014/05/book-of-xx...

[bbcbasic]

Still confused! With a balloon surface if you travel in one direction long enough you will end up back where you started. Does this analogy apply to the universe.

If there is no centre then either the universe is infinite, or it wraps around on itself like a balloon?

[everyone]

I believe whether the universe wraps around, or is infinite is still a matter of some debate. I know some researchers are currently trying to determine the size and shape of the universe by trying to see all the way to the other side and back to our side, for example. In some cases with things in physics and cosmology, lets say dealing with 4 or 11 spatial dimensions you've just got to accept that our minds are not designed to be able to visualize some concepts, though we can understand and make progress by understanding the math. Heres a random article introducing some ideas about the geometry and topology of the universe. http://io9.com/5811706/if-you-keep-going-around-the-universe...

[castis]

but if you played the expansion backwards, would it not arrive at a location somewhere vaguely equidistant from the farthest edges of said expansion?