Hello! I am a huge fan of both Star Trek and the Book of Mormon musical and am outlining a cross-over fic idea, however I am stuck on the sci-fi/tech aspect of something (see below). So there's 2 boys who are Mormon missionaries in the year 2018 (or some year around our time) who are walking around in Uganda (where their mission is located) to go find their friend who had wandered off and it's starting to get late. Meanwhile, in the 23rd Century in an alternate dimension that mirrors the Star Trek universe down to the smallest detail, the same 2 boys (duplicates, for lack of a better word) are also wandering in the same spot during a mission (they are ensigns or cadets - haven't decided yet). I want there to be this situation where they encounter a device that somehow sends the 2 boys from the 23rd century to the 21st and vice versa. There's a whole ton of plot and relationship stuff but the part I don't have down is the technobabble excuse for why this could happen. The idea is super out there and far-fetched so I am not sure I can pull it off in its current state. Does anyone have any ideas for a more plausible tech-y excuse for why this could happen? I just need the duplicates to switch places with each other, thus forcing them to each navigate a world that is foreign to them, yet inexplicably the same.