Time travel shows up constantly in science fiction, but this Spark documentary follows physicists treating it as an open engineering question. Researchers explain wormholes as solutions permitted by Einstein's equations, and the film visits labs working with entangled photons and time crystals, materials that repeat a pattern in time rather than space. Interviews with working scientists lay out what would actually be required to bend spacetime into a loop, and where the theory runs into walls: the exotic negative energy a traversable wormhole would need, the paradoxes a working time machine would create, and the gap between what the math allows and what any lab could build. The tone stays grounded rather than speculative, with researchers repeatedly separating what current experiments demonstrate from what remains purely theoretical. Archival diagrams, lab footage, and talking-head explanation carry the hour, building from basic relativity toward the strangest edges of quantum mechanics, and ending with an honest accounting of how far current physics is from anything resembling a time machine.