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From: Lynn.es@Xerox.ARPA
Newsgroups: net.space
Subject: Re: Big Bang
Message-ID: <12115@sri-arpa.UUCP>
Date: Mon, 9-Apr-84 14:19:10 EST
Article-I.D.: sri-arpa.12115
Posted: Mon Apr  9 14:19:10 1984
Date-Received: Sun, 15-Apr-84 00:51:33 EST
Lines: 29

Although we haven't found enough matter to gravitationally stop the
expanding universe in the distant future, there are a couple of
indications that there may be hidden stuff that will do the job.  First,
some galaxy rotational studies show that what we see in galaxies is
surrounded by a lot more matter that we don't see.  Second is the recent
measurements that seem to indicate that the Neutrino may have a small,
but non-zero, rest mass.  This particle should inhabit the universe in
incredible numbers according to current theories of nuclear fusion, and
might, even with a tiny mass, add up to more mass than the matter we are
used to.

Now for the real question you posed (WHAT WAS THE FIREBALL EXPANDING
INTO ?).  By general relativity, we consider space itself curved by
gravity.  If the universe has enough mass to eventually collapse, then
space actually curves around on itself.  There is no outside (not in
three dimensions), you just come back on yourself eventually.  If the
universe is not gravitationally closed, then it's even harder to
explain.  I guess it's something less than empty space.

Incidentally, we don't know that the big bang started as a point.  We
just don't know of any limit to the density of matter, so when we
extrapolate the expansion backwards, it reaches a point.  

"what lies beyond the 20 billion light-year barrier"?  Unless we can
find some means that transmits information faster than light, we will
never know what is beyond the barrier, that is, beyond x light years,
where x is the age of the universe.

/Don Lynn