Travel between different universes, or as it is known by its scientific name, an "orthogonal multiverse coordinate change", is a form of space travel. To be precise, quantum technology is used to travel to another place in the multiverse. Reality is much greater than just what we see in our universe. Other universes exist and they sometimes interact with our own universe. It's the nature of the multiverse. Within the multiverse, the universes are constantly splitting, which means that many other universes are very similar to ours. And it is the similar ones that interact.