According to the Big Bang theory, there is absolutely nothing outside the expanding universe. All that is is being created within the expansion. Furthermore, there is no one center to the expansion. Everywhere is the center. ie, every point within the universe see everything else expanding away from it at the same (accelerating) rate.
It is hard to accept that we are alone in the universe and that interstellar, let alone intergalactic, travel is impossible. Accept we must. I am not saying that our solar system isn’t worth exploring, but that’s it. The laws of physics and the human condition say we are stuck here.
That's where my brain starts a meltdown. I can't imagine "nothing" and its ability to have something expand into it. I've just got to accept the fact that I don't have the tools of a Hawking, drop this topic, and go back to thinking about sex.