In science fiction, hyperspace is any region or continuum of space co-existing with our own universe (in some cases displaced in an extra spatial dimension) which may be entered using some sort of energy field or space-altering method. While hyperspace is in some way anchored to the normal universe, its properties are not the same as normal space, so traveling in hyperspace is largely inequivalent to traveling in normal space. This makes for a very good explanation of faster than light (FTL) travel: while the shortest distance between two points in normal space is a straight line, hyperspace allows those points to be closer together, or a curved line in normal space to be straight, etc. Hyperspace is the most common device used for explaining FTL in a science fiction story where FTL is necessary for interstellar travel or intergalactic travel.

In many stories, a starship cannot enter or leave hyperspace too close to a large concentration of mass, like a star; this means that hyperspace can only be used to get to the outside edge of a solar system, and then the starship must use other means of propulsion to get to or from the planets closer to the star. The explaination being that mass affects gravity in normal space, and therefore the curvature of hyperspace like the shadow of a large object in front of a source of light. Sometimes this is simply a plot device so that a starship can't easily escape by conveniently slipping into hyperspace, thus ensuring epic space battles. Other writers have limited access to hyperspace by requiring a very large expenditure of energy in order to open a link (sometimes called a jump point) between hyperspace and normal space; this effectively limits access to hyperspace to very large starships, or to large stationary jump gates that can open jump points for smaller vessels. The source of energy required for hyperspace travel is frequently taken for granted, unless it is a plot device.

Hyperspace is usually portrayed as either being completely empty, with a gray or black appearance, or as being full of shifting, luminous tendrils and clouds of... something; imagine a universe crammed full of nebulas. The visual interpretation of being in hyperspace is fairly open to interpretation, but is presumed to be remarkably different from the vaccum of normal space.

Star Control II has an example of the latter, in it, hyperspace has a strange red glow, indeed everything in it turns red (including your starship), and various strange patterns of flashes and shooting stars are in abundance. According to the Star Control version, Hyperspace ends at places of high gravity, such as stellar systems, and if two spaceships come into distance within each others fields of gravity, both will tumble out of hyperspace.

An idea similar to hyperspace, called hyperstate, was introduced by David Gerrold in The Voyage of the Star Wolf. In this setting starships used artificially-produced gravitational singularities (the space-time distortions found at the center of black holes) to transition between normal space and so-called irrational space, where faster than light travel was possible. The primary limitation of hyperstate was that the resulting gravitational distortions could be easily detected by other starships, so stealthy movement at faster-than-light speeds was effectively impossible.

The Star Trek universe equivalent of hyperspace is known as subspace. Although similar in concept to hyperspace, subspace plays a slightly different role in FTL travel. When a starship is traveling at FTL speeds (commonly known as "warp speed" in the Star Trek universe), the ship itself does not enter subspace. Instead, the ship is surrounded by a field of energy, a warp field. It is the warp field that extends into subspace, allowing the starship to travel at FTL speeds while it remains in normal space. This concept of FTL travel is limited by the idea that if the warp field is too strong, the ship itself will be completely submerged in subspace and thus travel at infinite speed, which has negative genetic effects on living things. In addition, at high warp factors (each factor being a subspace field layer surrounding a ship) the energy required to sustain the field grows exponentially. A majority if not all technologies unique to Star Trek are based on subspace in one way or another. Among these is using subspace as a medium for propagating audio/visual signals at FTL speeds, thus allowing realtime communication across distances of several light years (a feat standard radio cannot perform.) Similar interstellar communication methods using hyperspace is frequently assumed to function in a convenient way in other science fiction works, but the technology is generally taken for granted.

In Douglas Adams's "Hitchhiker's Guide to the Galaxy," there is a brief description of the effects of hyperspace between the characters Ford Prefect and Arthur Dent:

Ford: "...It's unpleasantly like being drunk."

Arthur: "What's so unpleasant about being drunk?"

Ford: "You ask a glass of water."

Fictional works featuring hyperspace

• Babylon 5
• Cowboy Bebop (anime)
• The Foundation Series
• Homeworld
• Honorverse (series)
• Star Control II (computer game)
• Stargate
• Star Trek (as subspace)
• Star Wars

References

• Hyperspace by Michio Kaku (Anchor)

• Surfing through Hyperspace: Understanding Higher Universes in Six Easy Lessons (Oxford University Press) by Clifford A. Pickover

• The Fabric of the Cosmos: Space, Time, and the Texture of Reality (Knopf) by Brian Greene
• Hyperspace A Vanishing Act by P. Hoiland

See also

• Fourth dimension
• Spacecraft propulsion
• Wormholes
• Warp drive