Part 2/16:
The idea is straightforward: if we can manipulate spacetime, why not create a bridge—a wormhole—that links here to somewhere far away? To make such a conduit feasible, one must understand what kind of matter and energy are needed. Einstein's field equations tell us that a wormhole would require exotic matter with unusual properties to stay open against gravitational collapse. Regrettably, the forms of matter—often termed exotic matter—necessary for wormholes tend to want to collapse, rendering them physically problematic, if not impossible.