Is the universe infinite or finite?

I just surfed in here, and I'm admit I'm just a 'raw amateur.' I know
you guys are all experts here, so it won't be any problem at all for
somebody to explain to me the really simple question I have been
wondering about for many years: Is the universe infinite or finite? (I
have asked this question casually of several other 'raw amateurs' about
what they think, and incredibly, I have received the response from more
than one: "I never thought about it"..... Yikes)! Thanks, Mike in L.A.

wrote:
I just surfed in here, and I'm admit I'm just a 'raw amateur.' I know
you guys are all experts here, ...

Do I detect a hint of sarcasm :-)

There are a few knowledgeable posters but most are just
interested laymen or amateurs with a generous sprinkling
of cranks for amusement.

so it won't be any problem at all for
somebody to explain to me the really simple question I have been
wondering about for many years: Is the universe infinite or finite?

Best information at the moment suggests infinite but it could be
just very much larger than the region we can see. The "observable
universe" is limited because the universe is 13.7 billion years old
so we can't yet see anything from which light will take longer than
that to reach us.

The simplest questions are sometimes the hardest to answer.
In this case, what indications do you think could be measured
that might differentiate between infinite and say a universe
which is a billion times larger in radius than the small region we
can observe?

"CeeBee" mentioned Ned Wright's tutorial which is an excellent
primer and he also has news related to cosmology on the intro
page:

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

He also mentioned a New Scientist article from late 2003 on a
paper suggesting evidence for a dodecahedral universe but this
paper was pretty much dismissed at the time because circular
patterns that should result don't appear to exist. Ned dealt with
that at the time:

http://www.astro.ucla.edu/~wright/ol...o.html#04Dec03

HTH
George

Dear mikestraton:

wrote in message
...
I just surfed in here, and I'm admit I'm just a 'raw
amateur.' I know you guys are all experts here, so
it won't be any problem at all for somebody to
explain to me the really simple question I have
been wondering about for many years: Is the
universe infinite or finite?

You have some very good answers so far. What does infinite mean
to you? Does it mean to travel forever (at any speed) without
hitting an edge? The answer is likely "yes". If it means that
the Universe has infinite volume at any instant, the answer may
be "no". Consider that a racetrack meets the first definition of
"infinite".

(I
have asked this question casually of several
other 'raw amateurs' about what they think, and
incredibly, I have received the response from
more than one: "I never thought about it".....
Yikes)!

Sometimes not answering a question is a means of building a
hunger. If you find the answer unsatisfying, perhaps you should
build your own?

David A. Smith

David A. Smith wrote:

What does infinite mean to you? Does it mean to travel
forever (at any speed) without hitting an edge? The answer
is likely "yes". If it means that the Universe has infinite
volume at any instant, the answer may be "no". Consider
that a racetrack meets the first definition of "infinite".

Nobody would think that a racetrack is infinite just
because one could travel round and round it forever.

Nobody is a kook, and he's the *only* kook who would
think that. All the other kooks disagree with him!

-- Jeff, in Minneapolis

Dear Jeff Root:

"Jeff Root" wrote in message
ups.com...
David A. Smith wrote:

What does infinite mean to you? Does it mean to travel
forever (at any speed) without hitting an edge? The
answer is likely "yes". If it means that the Universe has
infinite volume at any instant, the answer may be "no".
Consider that a racetrack meets the first definition of
"infinite".

Nobody would think that a racetrack is infinite just
because one could travel round and round it forever.

Nobody is a kook, and he's the *only* kook who would
think that. All the other kooks disagree with him!

You really should be a little more circumspect in calling people
kook, Jeff. You may end up offending the OP.

As to your claim, notice that the balloon analogy is a 2D version
of the racetrack, in which it also describes an infinite
Universe, as long as you stick to the surface. The fact that
expansion increases any circumference (great circle) faster than
c, is simply icing on the cake (in my opinion).

Now will you call everyone who invokes the balloon analogy a kook
also? I'd be in really great company if you did that.

David A. Smith

David A. Smith replied to Jeff Root:

Nobody would think that a racetrack is infinite just
because one could travel round and round it forever.

Nobody is a kook, and he's the *only* kook who would
think that. All the other kooks disagree with him!

You really should be a little more circumspect in calling
people kook, Jeff. You may end up offending the OP.

There's no reason to think the original poster is a kook.

What I said was that nobody would think that a racetrack
is infinite just because one could travel round and round
it forever. Apparently I was wrong, and there really *is*
one person who would think that.

As to your claim, notice that the balloon analogy is
a 2D version of the racetrack, in which it also describes
an infinite Universe, as long as you stick to the surface.
The fact that expansion increases any circumference (great
circle) faster than c, is simply icing on the cake (in my
opinion).

The balloon analogy only applies to a closed Universe,
which would be finite. The surface of a balloon is finite.

I'm sorry I mentioned kooks. I did it because when I said
nobody would think a racetrack is infinite just because one
could travel round and round it forever, I figured you'd
reply that a kook would think so.

I'm sorry I replied to you at all, because you seem to have
become a kook. That is a recent development.

-- Jeff, in Minneapolis

Dear Jeff Root:

"Jeff Root" wrote in message
oups.com...
David A. Smith replied to Jeff Root:
....
I'm sorry I replied to you at all, because you seem
to have become a kook. That is a recent development.

I would have asked you your *functional definition* of
"infinite", but I guess the point is moot. Emotional labels seem
to be more important to you. I may have conflated "unbounded"
with infinite, but I guess we'll get to discover that with
someone lese.

Goodbye.
plonk

David A. Smith

In message .com, Jeff
Root writes
David A. Smith replied to Jeff Root:

Nobody would think that a racetrack is infinite just
because one could travel round and round it forever.

Nobody is a kook, and he's the *only* kook who would
think that. All the other kooks disagree with him!

You really should be a little more circumspect in calling
people kook, Jeff. You may end up offending the OP.

There's no reason to think the original poster is a kook.

What I said was that nobody would think that a racetrack
is infinite just because one could travel round and round
it forever. Apparently I was wrong, and there really *is*
one person who would think that.

As to your claim, notice that the balloon analogy is
a 2D version of the racetrack, in which it also describes
an infinite Universe, as long as you stick to the surface.
The fact that expansion increases any circumference (great
circle) faster than c, is simply icing on the cake (in my
opinion).

The balloon analogy only applies to a closed Universe,
which would be finite. The surface of a balloon is finite.

I may be missing something here, but what do you mean the balloon
analogy? The one I'm familiar with is about dots on a balloon
representing galaxies in space, and has nothing to do with the universe
being infinite. It's about the galaxies not expanding with the universe
(and AFAIK that is _still_ only theory, and observations to prove or
disprove it aren't yet possible).

On Tue, 13 Dec 2005 08:33:27 +0000, Jonathan Silverlight
wrote in sci.astro:

I may be missing something here, but what do you mean the balloon
analogy? The one I'm familiar with is about dots on a balloon
representing galaxies in space, and has nothing to do with the universe
being infinite.

The balloon (and any sphere) has the peculiar property that it is
finite, although there is no boundary. I think the universe has the
same property.
--
José

Jonathan Silverlight wrote:
(and AFAIK that is _still_ only theory, and observations to prove or
disprove it aren't yet possible).

Jonathan, I'm surprised! If it hasn't been tested then
it isn't a theory, only a speculation.

George