Well, our universe has got a very peculiar spacetime geometry (please have a look at my post (The shape of our Universe…… is flat, a sphere, a doughnut? What is outside, more space? Does it have an edge, a centre? A beginning, an end? It pop up from a singularity (what was it?) It’s expanding into what? (Part 1 of 3).). Our universe has got neither a centre nor an end since the main corpus (body) of it has got an Euclidean geometry, and near the borders you find Riemannian geometries full of curved trajectories which always take you back when traveling along straight trajectories according to your navigation instruments. The only way to go outside our universe is by means of a gigantic quantum wormhole which can take you to “another” universe. If you want to travel to any star within our own galaxy using a gigantic quantum wormhole, you’d need the energy of several thousands of stars to build it. But to build a gigantic wormhole to travel to another universe, you’d need the energy of an entire galaxy or the energy of a huge quasar. Now you know, you should start building a quantum wormhole now, but please be careful when selecting the universe you wish to travel to, it must have the same physical laws (and its constants) as ours. Otherwise (with different physical laws), as soon as you pop up in the other universe, you would be immediately disintegrated (in a tremendous cosmic explosion).