Seriously, though? Whenever I look at the sky, I always wonder: what is on the outside of our cosmic bubble? The universe expands at a rate of around 1 trillion trillion trillion light-years per second. It would take one heckuva rocket engine to get to its end. But here's another random thought: compare the universe to a rubber band; when you pull it, it stretches. Like how our universe expands. ...But when you let go, it INSTANTLY snaps shut. My point is, if the universe were expanding, chances are its contraction would be around a 1000 times faster, so we'd never feel it. Back on track: what is on the outside of our universe? It's like a video game: there's an invisible wall. There is another side. But you cannot reach it. If you try, your character dies. It's impossible to imagine nothing on the outside of a barrier. What is outside the universe's boundary? What does that boundary look like? It freaks me out just thinking about it; like humanity isn't ever supposed to know the answer. Try it: try thinking of an "outside" to the universe. It will give you a headache. What's preventing us from imagining the outside of the universe???