Wormholes are passageways through space-time, that are essentially connecting points between two separate distances or locations in the universe. If visualized, a wormhole is a tunnel connecting two different points in space time, or different galaxies. The best and simplest way to show this phenomenon is a paper example when two dots are drawn at the opposite end of the paper, the paper folded in half and a hole pierced through the dots connecting the two dots with a pencil.
Wormholes are based on a solution to Albert Einstein’s equation of general relativity, the equation for which accounts for the short child wormholes or Einstein Rosen Bridges which essentially actas giant blackholes linking two areas of space time. The theory suggests that the matter and light that is absorbed from one end escapes out of the other at the point known as a whitehole. This whitehole will be located somewhere else in the galaxy or maybe even in some other dimension.
These theoretical wormholes can be utilized for a variety of different things. Some say that travelling through a wormhole would take less time than through actual space. They could be used for faster than light travel as part of our far off future existence where space and time can be zapped between galaxies creating enormous shortcuts between any two destinations. Traveling at light speed seems impossible but we could easily travel faster than light using a wormhole. There are also theories surrounding significant gravitational fields. For example if we can place one end of a wormhole close to a blackhole which has an incredible amount of gravity and acts to slow down the apparent time, the link between that place and somewhere else could provide the means of travelling through or from the future.
This theory relies on the many-world’s hypothesis and interpretation of Quantum Mechanics that suggests infinite universes in timelines. According to this idea, every choice or branching path that we take in our timelines, exits in an endless list of others. Stephen Hawking suggested that wormholes could be all around us but they are microscopically small, existing in very deceptive spacetime as nothing is completely flat or solid. According to this theory, there are incredibly small holes in every piece of matter including time itself, even smaller than the atoms. However, being so tiny we can’t even imagine to travel between them or manipulate them.
Of all the options, this is the least likely scenario, primarily because we are not even sure if the many wormholes interpretations have any basis in reality because scientists are not sure if wormholes exists. They exist in theory, but there is no empirical proof that they are there. The whole idea is still far more science fiction, than fact.