Roger wrote:

I was hoping someone could help me with the following question. I am trying
to understand something of the size of the universe, and I came accross a
quote that said "the universe is expanding in all directions, and that the
'Cosmic Microwave Background' (the remaining heat from the Big Bang, is
found at a distance of 15 billion light years from us in all directions."

Tow questions result from this:
- does this not suggest the universe is ball-shaped, and
- that the earth is pretty much at the centre of the universe, near where
the Big Bang occurred?

Any input you can give me (in laymen's terms, please) would be welcome!

Rogier


imagine the surface of an inflating balloon.
there are a number of dots inked on it. these
dots are attached and not part of the expanding
rubber surface, so they do not grow in size as
the balloon inflates. one of these dots is where
we are. from our vantage point it looks like all
the dots are receding from us. the dots further
away are receding faster because there is more
expanding balloon between us and them.

in the rubber space between the dots there is a
residual glow from the big bang, your cosmic
background. the bang corresponds to when the
balloon was empty. the cosmic background reveals
when the balloon was empty.

notice that our dot is not at the center of the
balloon's surface, nor is any other dot. infact,
also notice, although i did not specify it, that
the balloon is not necessarily spherical. it might
be close to exact to satisfy certain cosmological
theories. now consider that the balloon's surface
is a two-dimensional surface.

in the real universe, the corresponding surface
manifests itself, as far as we can be practical about
it, as a 3-dimensional surface in a higher order
setting. we are as hampered in comprehending the
actual picture as 2-d creatures on the balloon would
be trying to imagine the center of the balloon or
being "inside" or "outside" of the balloon.


- nate