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Hyperdrive is a name given to certain methods of traveling faster-than-light (FTL) in science fiction. Related concepts are jump drive and warp drive. The idea of a hyperdrive in most science fiction relies on the existence of a separate and adjacent dimension most commonly called "hyperspace," though various other names have been used: "Drivespace," "The Immaterium," "slipspace," "Space2," "subspace," "Space Jump," "Zero-space," etc. When activated, the hyperdrive shunts the starship into this other dimension, where it can cover vast distances in an amount of time greatly reduced from the time it would take in "real" space. Once it reaches the point in hyperspace that corresponds to its destination in real space, it re-emerges. Usually, hyperdrive refers to a method of travel in which it takes a measurable amount of time to go from one point to another. When the distance is covered instantaneously, the term jump drive is often used. Fictional explanations of why ships can travel faster than light in hyperspace often accompany the storyline of novels, television programs, and films in which they are featured. Distances in hyperspace may be smaller than or geometrically inverse in relation to real space; it may provide a shortcut between two points in real space, thus effectively increasing the ship's speed by reducing distance travelled rather than time taken; perhaps the speed of light in hyperspace is not a speed barrier as it is in real space. Whatever the reasoning, the general effect is that ships traveling in hyperspace seem to have broken the speed of light, appearing at their destinations much more quickly and without the time dilation predicted by the Special Theory of Relativity. ==Characteristics== While in hyperspace, spaceships are typically isolated from the normal universe; they cannot communicate with nor perceive things in real space until they emerge. Often there can be no interaction between two ships even when both are in hyperspace. To people traveling in hyperspace, time typically moves at its normal pace, with little or no time dilation; 24 hours in hyperspace equates to 24 hours in real space. This is due to the fact that typical hyperdrive scenarios involve only changing the ''position'' of the craft, without altering its ''velocity'' (i.e. a ship will emerge with the same momentum, kinetic energy and direction of travel that it had upon entering hyperspace, thereby avoiding relativistic effects). One exception is David Brin's Uplift Universe; here, hyperspace is divided into "levels" where time passes at different rates. Hyperspace itself may be portrayed as swirling colours, total blackness, featureless grey, blank white (e.g. animorphs), or as something that would drive a human mind insane should it be viewed. In much science fiction, hyperdrive jumps require a considerable amount of planning and calculation, with any error carrying a threat of dire consequences. Therefore, jumps may cover a much shorter distance than would actually be possible so that the navigator can stop to "look around": take his bearings, plot his position, and plan the next jump. The time it takes to travel in hyperspace also varies. Travel times may be in hours, days, weeks or more, and in those cases can provide a setting in itself for a story that takes place during an extremely long journey. Hyperdrives allow for drama in science fiction by eliminating the single biggest problem with space as a setting for a story: the vast majority of space is empty and thus more or less uninteresting. As in most depictions of hyperspace ships with hyperdrive can typically only interact with other ships while in "normal space", they would have to drop out of hyperspace to interact, and the chance of two ships appearing at the same location in deep space to take a navigation bearing at the same time is infinitesimal. Therefore, hyperdrive ships will encounter each other most often around contested planets or space stations, which can be light-years apart. Hyperdrive may also allow for dramatic escapes as the pilot "jumps" to hyperspace in the midst of battle to avoid destruction. Dramatic tension can also be evoked by the use of "Jump Calculations" in the same way. (e.g. "Will the computer or crew be able to calculate the needed equations before being sucked into a black hole or before a group of missiles hits the ship?") Hyperspace also provides the means by which the literally astronomical distances between stars can be traversed in such a way that would enable an author to have a plot that deals with multiple star systems in a reasonable amount of time, something generally impossible if speeds less than the speed of light are observed. Authors that write about interstellar cultures without hyperdrives generally wind up with plots that last for centuries or more, something not all authors are willing to do or even capable of. Given how critical transportation is to every human culture, it is unsurprising that in an interstellar culture, which must deal with distances orders of magnitude greater than terrestrial cultures, the unique ways in which interstellar travel is described in various fictional universes tends to create major plot elements in that universe. In some science fiction, hyperspace travel is portrayed as potentially dangerous due to the chance that the route through hyperspace may take the ship too close to a celestial body with a large gravitational field, such as a star, or a black hole. In such scenarios, if a starship passes too close to a large gravitational field while in hyperspace, the ship is forcibly pulled out of hyperspace and reverts to normal space, or in some stories, is destroyed. Therefore, certain hyperspace "routes" may be mapped out that are safe, not passing too close to stars or other dangers. Some science fiction universes have used some such "dangerous routes" to cause travel to occur in time, rather than space. Two examples exist within ''Star Trek'' — notably the first season episode ''Tomorrow Is Yesterday'' (by accidentally coming too close to a "black sun") and in the movie ''Star Trek IV: The Voyage Home'' (by deliberately warping away from a close approach to the Sun), and in the sci-fi series ''Stargate SG-1'' (first in the episode "1969"), which for the Stargate series' episode was caused by travel near to a solar flare. In some science-fiction universes, artificial gravity wells may be used to force another vessel to drop out of hyperspace. Other portrayals show less interaction between normal space and hyperspace, so that ships may actually pass ''through'' the position taken up by a celestial body in real space, without being affected. Various other properties of hyperspace have appeared in fiction, such as the presence of seemingly alive hyperspatial beings, unwanted side-effects in the normal universe caused by hyperspatial travel, etc. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hyperdrive」の詳細全文を読む スポンサード リンク
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