Not 100% proof. That would require the universe to be infinite, which it still might not be if the curvature is within the tiny margin of error. It’s close enough to proof that it might as well be the case. The entire universe couldn’t be less than something like 130x the size of the observable universe, though… unless it has nontrivial topology. There’s always a caveat.
Aren’t we, the humans, the direct proof that if we exist - something else somewhere else exist too?
Not 100% proof. That would require the universe to be infinite, which it still might not be if the curvature is within the tiny margin of error. It’s close enough to proof that it might as well be the case. The entire universe couldn’t be less than something like 130x the size of the observable universe, though… unless it has nontrivial topology. There’s always a caveat.