Actual Infinity in Reality?

[GrandizerII]

Yeah, I was doing some reading on this some few hours ago and came upon the balloon analogy to explain how a finite universe could expand into "nothing". The flat universe seems to be almost a given now in astrophysics, am I right? I find this one really interesting as I always thought of it as a sphere ...

Anyhow, the analogy is good at illustrating what it could be like for a finite universe to expand "out of nothing" and/or "into nothing", but then in this case, the way I avoid the problematic existence of "non-existence" beyond spacetime is to posit a wider cosmos (perhaps a multiverse of universes), one from which finite universes spring forth into existence. Perhaps each time slice is like a frame in a 4D (or higher) kind of reality, and so that reality is still something into which the 3D sphere is embedded. Finite totality of existence seems to imply the existence of "non-existence" beyond it, and I find that problematic. Anything about which you can say is beyond or outside this or that is a something as far as I'm concerned, even if it's not the same nature as the spacetime we speak of here.

Which ultimately means that the concept of 'spacetime' as literally *all* of space and *all* of time as a single entity is part of your difficulty. Absent a multiverse (which only pushes the problem up one level since in almost every multiverse model, the multiverse is expanding), everything is part of spacetime.

There is no 'outside'. And expansion is just to the next cross section, not into anything 'outside'.

If it's an infinite universe expanding, there's no "outside" problem. If the totality of existence is finite, however, then yes, there is an "outside" that is "nonexistence", even if the expansion itself is just to the next cross section.

Just trying to counter this with words like "there's no outside, everything that exists is all contained in the spacetime" doesn't negate the logical mandate that there is an "outside". If we go with the premise, we have to follow through with it to the conclusion implied. We can't just stop at the premise and be satisfied.