@ETpro
Disclaimer: Obviously, I am very very much a layman so somebody correct me if I say anything ridiculous.
How do you conceive that space-time is bounded? What do you run into at its outer limit? Can you tell as you approach that limit that you are nearing a wall, or do you just vanish when you penetrate it?
My train of thought is (and obviously this is just speculation, and but one of many many possibilities) that there could be a fourth spatial dimension that we don’t perceive. I can’t think of any way to explain the looping effect this could have without using this metaphor: imagine that there’s a creature who thinks he’s living in two dimensions that exists on the surface of the Earth. He wouldn’t be exactly two dimensional because of the Earth’s curvature. However, since the Earth’s radius is very very large in comparison to him, the curvature is very gradual and he therefore doesn’t realize it exists. Now, he plants a flag in the ground and starts walking in what he thinks is a straight line leading directly away from the flag. In due time, he circles around the Earth and ends up right back where he started at his flag. It’s very hard to think about four dimensions, but I’d suppose by extrapolation that it’d be possible that space itself could have a slight curvature in the fourth dimension that would bring us right back to Earth if we sent a spacecraft far enough away. No boundary, no “wall of the universe.” Just walking in circles. It’s a kind of neat concept to think about.
And then, can I not divide a single inch into infinitely smaller increments, or is there some limit where division simply fails to work?
Up higher I wrote this: “Then there’s the idea that perhaps we can get infinitely small, that we can just keep splitting distances in half forever. But probably the existence of fundamental particles disproves that (I wonder, though, if empty space has a fundamentally small unit).” I think because matter is quantized, you can’t legally divide something as many times as you want. But who knows, really.
Part of the reason I’ve taken such interest in this question is that I once asked a very similar question at the debate site I used to frequent before it shut down, except that I think I phrased it, “Does infinity exist in the physical world?” By this I meant that numbers could only be included if they were shown to actually exist somewhere other than our minds. Somebody mentioned irrational numbers (infinite precision) and I shot them down with the claim that irrational numbers probably don’t show up in the real world. I said that there probably doesn’t exist a circle whose circumference is equal to its diameter times exactly pi. Simply due to the fact that the real world isn’t like the Cartisian plane: perfect curves cannot exist because matter is quantized, and so two particles sitting next to each other would technically make a straight line – rather than a circle, it would be a shape with an extremely large number of sides that is almost a circle. However, now that I think about it further, aren’t black holes supposed to be perfect spheres? That would be a physical manifestation of pi.
Goddamn, sorry this is so frickin’ long.