Wormhole travel. Conceptual computer artwork of travel through a wormhole, represented by the Earth and its Moon entering at right and leaving at left. Wormholes are a theoretical solution to Einstein's equations of space-time. Space and time are not invariant, and have to be treated as a single, unified entity called space-time, seen by the grid pattern at each end of the wormhole. It is thought that at the smallest scale of the universe (the incredibly small Planck length), the fabric of space-time is riddled with wormholes. The concept is also found in science fiction, where they are used to travel between distant points of the universe. However, as wormholes would last for less than a second, such use would probably be impossible.