Interstellar and The Once Destiny, trying to change the past through time and space, can all be attributed to the recognition of parallel universes. Especially after Nolan showed five-dimensional space-time from a three-dimensional perspective, I think it is easier to understand the parallel universe. Just as the two-dimensional world can record different stories page by page like books in a bookcase, it can even be used as a weapon to suppress higher life, so is the parallel universe I understand. Although Nolan indicated in Interstellar that the long history of a universe is like a book or a bookshelf, and each moment (three-dimensional space) is just a page, you can refer to the stacks of bookmarks in the library drawer. People want to find a book through bookmarks (which can be understood as the help of a three-dimensional world to a two-dimensional world), so people can shuttle (or come) to the past by looking for bookmarks. I think the theory of parallel universe first appeared because people who want to take regret medicine gradually discovered various unexplained time paradoxes and conceived new "regret medicine". On the whole, it is the same as our cosmic development plan. From the emergence of life to the unity of mankind, even the historical trend is divided into "the same" or "roughly the same" or "completely different". Naturally, the theme of this crossing is based on two or more parallel universes with exactly the same historical development, which is fully played by the previous destination (or the original author). A person travels through time and space and becomes a participant in his own life. At first glance, it's jaw-dropping (thanks to the development of the Internet, the short version of Your Resurrected Bodies has been worn online for several years, so that it's no surprise to watch movies), but in fact, it's the same character in multiple universes trying to change his life.