Quote:
Originally Posted by Brian W
Aha! that is just what people keep telling me 'there is no centre' but even on a flat rubber sheet there is a spot that is the centre.
However ... would it change the parameters of the discussion if instead of 'centre' I was to refer to the single place where it all began?
Brian
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In the balloon analogy, you have a balloon with dots on it representing galaxies. The two dimensional surface of the balloon represents three dimensional space. As the balloon expands, the dots (galaxies) move away from each other. In this analogy, where is the centre?
There isn't one.
Because this is a two-dimensional analogy of three-dimensional space, you can't say that the centre is inside the balloon. That would be the three-dimensional centre and that's not allowed in a two-dimensional model.
So asking where the center is in three dimensional space is like asking where the centre is on the SURFACE of a balloon. There isn't one.
Before the balloon began inflating, all the dots on the balloon's surface were close together - ideally infinitely close together. But once it starts inflating you can't point to a spot on the surface and say 'that's where the balloon started inflating'.
The key is that the expansion on the universe did not start at some point in three-dimensional space. Rather, space itself began tiny and got bigger.