Is the universe "finite" or "infinite"

Your original post said that if you sailed out forever you would either hit a wall or the universe is infinite. This is WRONG. The universe can be finite AND without walls. If you sailed forever and never hit a wall, it would NOT demonstrate that the universe is infinite.

 

It depends on what you define as the Universe.

If you just mean the stars and crap that we can see, then yeah, that is finite.

If you mean the medium in which that finite mass is expanding, then yeah, I think that is probably infinite.

 

So help me out here. Lets say we sent probes out in every direction in a straight line. Would they continue on that straight line indefinitely? Would they be forced to change directions and cross paths? Don't mind that we can't send probes indefinitely in all directions and they would separate as their paths separated from different angles, for the purpose of the question just assume they are really good probes the duplicated themselves and would split during travel to fill all directions.

 

That's the way I see it, I think. There could be an infinite number of these stars-and-crap systems. If "everything" is a Hilbert space, there'd be plenty of room for an infinite number of universes.

 

Here's an interesting question: Is the universe infinitely small?

One interpretation of Bell's theorem is that the universe is nonlocal. This may mean that every point in space is connected regardless of the amount of space between them. Another way to state this is to say that every place is right next to every other place, or that everywhere is in the same place.

Most people intuit that this means the universe must have no features, like a true Euclidean point, and must therefore be false since the universe clearly has features.

But again we can invoke Cantor's set theory to rescue ourselves from this colorless fate. Cantor demonstrated that there are layers of infinity, which he labelled cardinalities. There are, of course, an infinite number of infinite cardinalities, from aleph null up to the ultimate aleph, which he called Omega. If there are layers of infinity, there are also layers of infinitesimals, which are fractional infinities.

Thus the universe could be infinitely small and have features, as it may correspond to merely one of the infinite number of infinitesimal cardinalities.

If we can demonstrate the viability, if not the factuality, of infinitely small universes, we can further propose that there might be Omega universes whose total size is zero, thereby solving the age old problem of something vs. nothing!

 

Wait. Are you saying the universe is infinite or the matter within the universe is infinite? Two different things. I believe, at least in 3D space, the universe has an infinite amount of space. But matter is finite. Energy is finite. There is an x amount of matter and an x amount of energy. I think just eventually you reach a region of just empty black space that not even light has touched yet.

 

One of the more recent ideas, that was partly suggested by cosmological evidence, is that the net energy in the universe is zero.

http://www.astrosociety.org/pubs/mercury/31_02/nothing.html

 

So this point in space is special some how and nomatter how far you go, you will never find another special spot with matter.... nothin but nothin eh?

 

If the universe is infinite, then it must have an infinite amount of matter.

I agree

LOL, yes... energy and matter exist only in this one magical area in a sea if infinite nothingness

And it goes on forever... I wonder why only "x" amount of stuff poofed into existence here, but nowhere else?

 

everything that is

Why, why only matter here?

a infinite universe doesn't "expand"

 

The Universe is only 6 thousand years old but it is finite. God made the heavens and the earth then he had finished it does not go on for ever heaven borders space.

 

Excellent.

 

What is "yom?"

 

Not everyone includes the void in "everything that is"...thats why I asked. That definition is relevant to the question.

Because thats all we have been able to confirm existing so far.

There is the mass that makes up our universe (including light and whatever) and there is the void it is expanding into. Some people consider that void to be the universe. Some people only consider the mass itself to be the universe.

If you consider the mass itself to be the universe (and not the void), then yes, the universe could be expanding.

 

I think the void is infinite, but the stuff isn't.

 

How can stuff only exist in "one" spot in an "infinite" void

 

So you believe this is the one magical spot that has matter?

we knew black holes existed before we detected one. We can know the universe has to be infinite before we can "prove" it.

If it exist, it's in the "universe"

huh? I think that for "x" amount of space-time, you got an average of "y" amount of matter.... for infinity

 

Because it can? How can't it?

 

OK so...where is that planet?

 

Everyone has done this...Take 2 mirrors, one smaller than the other, hold the smaller one with mirrored side facing the larger one and look over the top of the smaller one. There will be what looks like an infinite number of images that resolve into nothingness. I think this explains one facet of the concept of infinity but, of course, the reflectivity of the mirrors and available light are physical limitations so, you get nothing but darkness at the very end.

 

This is the only one we can see so far. Magic is not necessary from what I have seen so far.

No, we predicted they might exist. Thats why actually detecting one was such a big deal.

If you cant prove it then how do you know it is true?

At least with black holes we had mathematics to predict them. What are you basing your own assumptions on?

Did I stutter?

 

If you have an infinite amount of nothingness... and at any point a universe can just poof into existance at random, means big bangs are going on all over, threw all infinity. There must be an infinite amount of stuff out there.

 

If you consider one of the individual bangs to be the universe (and by some definitions it is), then yes, the universe is finite and expanding.

 

I'm talking about the big picture. I'm sayin you can travel in a line forever, and never stop passing stuff.

 

You could do that in an expanding and finite universe under our current laws of physics. As long as you were travelling at the speed of light or slower.