Thanks. So what’s outside of the greater universe then?
I’m just an interested layman, definitely not an expert, but before someone came up with the idea of a multiverse (which is still quite controversial), I think most astronomers and physicists would’ve said there’s is nothing outside of our universe. Our universe is all there is, and it’s expanding. It’s not expanding into something that’s “outside” of it, like a cake in an oven, rather it’s expanding in the sense that new space is being created all the time that wasn’t there before.