Re: Probably a dumb question ...


"Zilva Zanga" <mercury@xxxxxxxxxxxxxxxxxxxx> wrote in message
news:43154f6e$0$8999$afc38c87@xxxxxxxxxxxxxxxxxxxxxxx

[Probably a dumb question ...]
> from someone with an interest but no education in this area.
> If the universe is expanding, doesn't that mean that there is a boundary
> to what scientists define as the universe? If yes, what's on the other
> side?

It is unlikely. There are two possibilities, one
is that the universe has infinite volume ("open")
while the other is that it wraps round on itself
like the old arcade game "asteroids", only in all
three directions, and has a finite volume ("closed").
What we can be fairly sure of is that, if it is
finite, the size is much bigger than the part we can
see so telling the difference is going to be really
difficult.

Image a *** of paper with a sprinkling of dots
representing galactic clusters at some time. If you
put it through a photocopier set for 10% magnification
you get a map of where they will be some time later.
It doesn't matter if that *** is just a tiny section
out of an infinite universe, the rest is doing the same.
Since an infinite space has no boundaries, there is
nothing to prevent it expanding.

If you are new to all this, have a read of Ned Wright's
tutorial and bookmark it, some will be over your head
but if you read a bit more on the subject, it is a good
site to use for reference:

http://www.astro.ucla.edu/~wright/cosmolog.htm

HTH
George


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