Universal Curvature

Today, I would like to address two questions, mainly for the purpose of organizing my thoughts.

1. What is the shape of the universe?
2. Is the universe really infinite?

Question #1

I have seen two basic models of the universe; perhaps there are more that I am unaware of. Model A depicts the universe as flat. Model B prefers to describe it as something like a ball.

I personally prefer the flat theory, and let me explain why.

It's easy to see how Model B arose. Say you have a balloon. You draw one circle at the top of the deflated balloon and one near the neck. You then proceed to blow up the balloon. As more air enters it, the circles you drew not only grow farther apart but also seem to expand within themselves, which would support universal expansion.

Yet here is where the ball theory begins to fail. The circles on the balloon represent galaxies. But galaxies do not expand--at least not according to theory. Only the universe itself does. The galaxies stay their respective sizes as they move away from everything else.

Here's another failing: If the universe is a ball and all the galaxies are situated on the surface of the ball, what is below the surface? What is on the inside of the ball? I don't think there is anything, because I don't think there is a ball. Overall, the flat theory just makes more sense.

Question #2

Suppose, for a moment, that the universe continues to expand for trillions upon trillions of years. Wouldn't there be a point where the universe would be stretched so thin that it would rip apart? Or, if you prefer the ball theory, wouldn't there be a point where it would pop, to continue the balloon metaphor? What would happen then?

That was completely unrelated to the question, I know. I just wanted to throw the out there. In brief, I'm glad I won't be alive at that point.

All right. To the question.

If the universe is truly infinite, how can it be expanding? Saying the universe is expanding implies that the universe is of a measurable size; otherwise, how would expansion be measured?

They have made maps of the universe, or have attempted to, anyway. You cannot make a map of an infinite thing because it would have no edges. This map (I've seen pictures) definitely has edges.

Maybe my mind just can't grasp the concept of infinity. Because if the universe is expanding, it has to be expanding into something. Into nothing? Nothing in itself is something. And what is true nothingness? What would it look like? As humans, we cannot imagine this. Try it. And don't tell me a black, empty void, because black is something. I don't believe in nothing. There cannot be nothing.

So, then, what is beyond the universe?

(And yes, I do realize I've completely gone off on a tangent. Deal.)

I'd like to think there are other universes. And even then, what is beyond those? There's got to be an end. My mind just can't fathom anything else. Maybe I'm wrong. But that's as far as my comprehension could ever go.

Ach. The limits of the human mind.