This is my favorite possibility, that space has a “finite volume but no edges: if you travel farther than the scale of the universe, you end up back where you started.” It’s comforting on an existential level to imagine the amount of stuff around us is finite.
“ The torus moves into itself and comes out at the other end, where the locations of ‘coming out’ could be what is driving what we observe as the expansion of the universe.”
It's also possible particles increase causing expansion, this is just theoretical still. But if that's true, then it is finite but perpetually increasing. Potentially infinitely.
Relative to what it was before. It has an intrinsic size. Think of it in terms of matter density if you find it more comfortable. The density simply goes down over time; distandes between galaxies increase.
Just because you can't measure something directly doesn't mean it doesn't exist. There's plenty of things we only know only through indirect measurement.
