"Davoud" wrote in message ...
Davoud:
I can think of no reason why the Universe can't have a central region
in three-dimensional space if the Big Bang theory is correct.

Greg Neill:
If the BB is correct, then every place in the 3D universe was
once co-located with the center. So there is no unique place
that one can call The Center, since every place equally
fulfills the role.

I have seen this argument in various guises. In /my/ /mind/ it breaks
down because of mixed verb tenses. "Every place /was/ /once/ co-located
in the center." OK, but "every place" departed the center when
space-time expanded, leaving the center behind. These "places" did not
all carry the center with them so that each one is now a center of its
own. Such a place -- a region that was denser than average due to a
quantum fluctuation and later became the core of a galaxy -- may be a
local center, but it is not the Universal center -- in /my/ /mind/ .

Your difficulty with this seems to stem from your adhering to
a model where things exploded out from a center into a
pre-existing space or void. This is not the case in the BB
model where space itself expanded. There was nothing at
all (not even space) "outside".


Simple common sense says that the two-dimensional surface of a sphere
has no center -- I figured that out for myself while playing with a
solid-color, featureless rubber ball as a child -- but if you look
beyond the surface, inside the sphere, you will find a center.

That's fine if you have the ability to look beyond the surface.
If you can't, then you're confined to looking on the surface.
The same thing holds for us, who can only point to things inside
the universe. There is no direction in all of space that we can
point to that is in the direction of a unique center in 3D space,
yet every direction points to the Big Bang (since we look back
in time as we look further out).