Re: The Universe

[Gary Karshner <Karshner@STMARYTX.EDU>]

Jim,
        Do I really want to get involve in this? The number of point in a line is
not countable. Since between any two successive points, I can find an
infinite number of rational numbered points, much less irrational ones.
        Now, on to what I profess to know something about - the universe. Whether
the universe is finite or infinite in size, in principle depends
fundamentally on whether it is open or closed. One of the great unanswered
questions of cosmology. Observationally we know there is a limit to how far
we can see. The three degree background radiation sets that limit. It comes
from a time when the universe became transparent, further than that cannot
be seen since radiation swamps out any information. This physical
limitation makes the number of galaxies uncountable physically.
        Mathematician define something as "countable" or numerable if you can
generate a procedure that will systematically allow you to enumerate each
one - time is never a factor for mathematicians! As physicists, we are
limited by both time and delectability as to what we can count.

At 08:28 AM 8/11/00 -0600, you wrote:
> I don't know how to formulate this question -- let me try the following:
> Is it really meaningful to ask how large the Universe is?
> or
> Is the Universe finite in size?
> or
> Is the number of stars (and hence presumably planets and presumably
> civilizations) countably finite?
> and
> BTW can I say that the number of integers is "countable" and still mean
> infinite?
> Can I say that something is "countable" and restrict my meaning to "finite"?
> OK OK OK that is more than one question. <g>
> Jim Green
> mailto:JMGreen@sisna.com
> http://users.sisna.com/jmgreen
Gary

Gary Karshner

St. Mary's University
San Antonio, Texas
KARSHNER@STMARYTX.EDU