FTL (faster-than-light) travel
In science fiction's two marquee franchises -- the Stars, both Wars and Trek -- the concept of faster-than-light travel is central to each fictional universe. In fact, the warp drive on the U.S.S. Enterprise may be the single most famous engine in history. FTL travel isn't a reality yet, of course, but there are some intriguing blueprints on the table. In 1994, Mexican theoretical physicist Miguel Alcubierre proposed a kind of warp drive engine that, mathematically, is valid within Einstein's general theory of relativity. More recently, Richard Obousy of Icarus Interstellar proposed a warpship design that would run on the universe's "dark energy."