If the Universe is ‘expanding’, what is it ‘expanding’ into?.............
Exactly. If matter is not present (and its affects on space-time) can there be space-time? The old tree falls in the forest question.
Wonder what the expanding boundary or the edge of the universe looks like? If it is expanding.
Space.
"Space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space." - Douglas Adams
Mark