You're going off the deep-end for fantasy when you start saying "pocket universes". Even dyson spheres are an exponentially advanced civilization problem, not j

You're going off the deep-end for fantasy when you start saying "pocket universes". Even dyson spheres are an exponentially advanced civilization problem, not just for energy but for material to build it from. To achieve frequent non-robotic travel beyond a solar system, a species would have to first master unlimited "free" energy (ie. fusion). This seems to be an extreme non-trivial problem. Even a civilization tens of thousands of years ahead of us may not have mastered it on a portable scale, limiting their travel and making "home" far more comfortable. And again, with unlimited energy, they still might not even feel the need to leave their solar system except for basic exploration, they might be xenophobic. If the spark of the dna for virtually all life on earth maybe came from somewhere else, injected into our potent primordial soup, perhaps it happened when the galaxy, even the universe was closer together so it didn't have to travel so far. But now the few other "cousins" of life we have in the galaxy/universe may be too far away simply from the expansion of space itself, not just big-bang momentum.