Thanks UT. I prefer to think of gravity as a manifestation of a
physical fourth dimension. It works to explain things in my mind easiest. And, exactly what I was thinking, a rasin bread has an edge, in the pan, in your oven. There's already
volume in that bread analogy.
You have to imagine that NOTHING exists except the balloon (..be the balloon
) Air, in the balloon analogy, is nothing, not even volume for things to exist in, and really the spherical shape is just to help with the expansion, it could be any shape.
Now, the 3 dimensional skin of this balloon represents a cross-section of a 4th dimensional sphere (balloons aren't spherical either, but let's try not to talk about the little knotted part... imagine it as
spherical.)
For the experiment's sake, let's say we're suppressing the Z dimension, so we have only X and Y across the surface of the balloon, warped through the 'W' dimension, i.e.: positive curvature. A slight depression in the W dimension (such as we would get if we put a penny on the surface of the balloon) could represent the type of distortion gravity might make.
This balloon universe, upon creation, was just a fleck of rubber. This rubber fleck was/is all of the material/energy that will ever be
in this universe. As it expanded, it carried energy along for the ride. As energy levels were spread over more volume a threshold was crossed and matter condensed out of this energy into this space...
That our universe appears to have expanded from more of a cube is another story...
[edit to add]
The important part, duh Trav... #-o
The important part remains, no point in space now is any closer to the 'center' than any other point. Every point was the center at one time and still is. Expansion is a term used irresposibly, it's more like, the fabrication of volume, that has everyone's perception twisted on this issue...