Immaterium

Hyperspace is a faster-than-light (FTL) method of traveling used in science fiction. It is typically described as an alternative "sub-region" of space co-existing with our own universe which may be entered using an energy field or other device. As seen in most fiction hyperspace is most succinctly described as a "somewhere else" within which the laws of general and special relativity decidedly do not apply – especially with respect to the speed of light being the cosmic speed limit. Entering and exiting said "elsewhere" thus directly enables travel near or faster than the speed of light – almost universally with the aid of extremely advanced technology. "Through hyper-space, that unimagineable region that was neither space nor time, matter nor energy, something nor nothing, one could traverse the length of the Galaxy in the interval between two neighboring instants of time."

Astronomical distances and the impossibility of faster-than-light travel pose a challenge to most science-fiction authors. They can be dealt with in several ways: accept them as such (hibernation, slow boats, generation ships, time dilation – the crew will perceive the distance as much shorter and thus flight time will be short from their perspective), find a way to move faster than light (warp drive), "fold" space to achieve instantaneous translation (e.g. the Dune universe's Holtzman effect), access some sort of shortcut (wormholes), utilize a closed timelike curve (e.g. Stross' Singularity Sky), or sidestep the problem in an alternate space: hyperspace.

Hyperspace is sometimes used to enable and explain faster-than-light (FTL) travel in science fiction stories where FTL is necessary for interstellar travel or intergalactic travel. Spacecraft able to use hyperspace for FTL travel are sometimes said to have a hyperdrive.

Detailed descriptions of the mechanisms of hyperspace travel are often provided in stories using the plot device, sometimes incorporating some actual physics such as relativity or string theory.

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