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Warp drive is a hypothetical faster-than-light (FTL) propulsion system in the setting of many science fiction works, most notably Star Trek. A spacecraft equipped with a warp drive may travel at apparent speeds greater than that of light by many orders of magnitude, while circumventing the relativistic problem of time dilation. In contrast to many other fictional FTL technologies, such as a "jump drive" or the Infinite Improbability Drive, the warp drive does not permit instantaneous travel between two points; instead, warp drive technology creates an artificial "bubble" of normal space-time that surrounds the spacecraft (as opposed to entering a separate realm or dimension like hyperspace, as is used in the Star Wars, Stargate franchise, Warhammer 40,000, Babylon 5, Cowboy Bebop and Andromeda universes). Consequently, spacecraft at warp velocity can continue to interact with objects in "normal space". Some of the other fictions in which warp drive technology is featured include: Stars!, EVE Online, Earth and Beyond, StarCraft, DarkSpace, Starship Troopers, Doctor Who and Star Ocean.
A theoretical solution for faster-than-light travel which models the warp drive concept, called the Alcubierre drive, was formulated by physicist Miguel Alcubierre in 1994. Subsequent calculations found that such a model would require negative mass, the existence of which has never been supported by any evidence, and prohibitive amounts of energy. However, it has recently been found that by changing the shape of the warp drive, much less negative mass and energy could be used, though the energy required is still many orders of magnitude greater than anything currently possible by human beings. NASA scientists have begun preliminary research on such technology.
Warp drive is one of the fundamental features of the Star Trek storyline; in the first pilot episode of Star Trek: The Original Series, "The Cage", it is referred to as a "hyperdrive"/"time warp" drive combination, and it is stated that the "time barrier" has been broken, allowing a group of stranded interstellar travelers to return to Earth far sooner than would have otherwise been possible.
The episode "Metamorphosis," also from the original series, establishes a backstory for the invention of warp drive on Earth, stating that Zefram Cochrane discovered the 'space warp'. Cochrane is repeatedly referred to afterwards, but the exact details of the first warp trials were not shown until the second Star Trek: The Next Generation movie, Star Trek: First Contact. The movie depicts Cochrane as having invented warp drive on Earth in 2063 (two years after the date speculated by the first edition of the Star Trek Chronology). By using a matter/antimatter reactor to create plasma, and by sending this plasma through warp coils, he created a warp bubble which he could use to move a craft into subspace, thus allowing it to exceed the speed of light. This successful first trial led directly to first contact with the Vulcans.
The later prequel series Star Trek: Enterprise describes the warp engine technology as a 'Gravimetric Field Displacement Manifold' (Commander Tucker's tour, "Cold Front"), and describes the device as being powered by an anti-matter/matter reaction which powers the two separate nacelles (one on each side of the ship) to create a displacement field (the aforementioned "bubble"). The episode also firmly establishes that many other civilizations had warp drive before humans; First Contact co-writer Ronald D. Moore suggested that Cochrane's drive was in some way superior to forms that existed beforehand, and was gradually adopted by the galaxy at large. Throughout the series, the viewer is made aware that the Vulcans have more advanced warp drive technology than humans even in the 22nd century. Enterprise, set in 2151 and onwards, follows the voyages of the first human ship capable of traveling at warp factor 5.2, which under the old warp table formula, is about 140 times the speed of light. In the episode "Broken Bow", Capt. Archer equates warp 4.5 as "...Neptune and back [from Earth] in six minutes", though previous Star Trek series had established that using warp drive within a solar system presents extreme danger to both the ship and the surrounding planets.
Plots involving the Enterprise traveling beyond warp 10 were once in the original series (such as warp 14.1 in That Which Survives), but for The Next Generation it was decided that these would no longer be featured. A new warp scale was drawn up, with warp factor 10 set as an unattainable maximum. This is described in some technical manuals as Eugene's Limit, in homage to creator/producer Gene Roddenberry. Normal maximum warp in the original series was warp 8.
The limit of 10 did not entirely stop warp inflation. By the mid-24th century, the Enterprise-D could travel at warp 9.8 at "extreme risk", while normal maximum operating speed was warp 9.6 and maximum rated cruise was warp 9.2. In the episode "Where No One Has..." the Enterprise-D was shown to exceed Warp 10, traveling a billion light-years from their home galaxy in a matter of seconds (though the ship's extreme velocity was due to the influence of an alien being, and could not be achieved naturally). The Intrepid-class starship Voyager has a maximum sustainable cruising speed of warp 9.975, the Enterprise-E can go even faster at Warp 9.995. In the alternative future depicted in "All Good Things..." (the final episode of the Star Trek:TNG), the 'future' Enterprise travels at warp 13, though it's never established whether this is 'above' warp ten, or simply the result of another reconfiguration of the warp scale.
Warp drive velocity in Star Trek is generally expressed in "warp factor" units, which—according to the Star Trek Technical Manuals—correspond to the magnitude of the warp field. Achieving warp factor 1 is equivalent to breaking the light barrier, while the actual velocity corresponding to higher factors is determined using an ambiguous formula. Several episodes of the original series placed the Enterprise in peril by having it travel at high warp factors; at one point in "That Which Survives" the Enterprise traveled at a warp factor of 14.1. In the Star Trek: The Next Generation episode "The Most Toys" the crew of Enterprise-D discovers that the android Data may have been stolen while on board another ship, Jovis. At this point the Jovis, which has a maximum warp factor of 3 has had a 23 hour head start which the Enterprise-D figures puts her anywhere within a 0.102 light year radius of her last known position. However, the velocity [in present dimensional units] of any given warp factor is rarely the subject of explicit expression, and travel times for specific interstellar distances are not consistent through the various series.
According to the Star Trek episode writer's guide for The Original Series, warp factors are converted to multiples of c with the cubic function v = w3c, where w is the warp factor, v is the velocity, and c is the speed of light. Accordingly, "warp 1" is equivalent to the speed of light, "warp 2" is 8 times the speed of light, "warp 3" is 27 times the speed of light, etc.
For Star Trek: The Next Generation and the subsequent series, Star Trek artist Michael Okuda devised a formula based on the original one but with important differences. For warp factors 1 through 9, v = w10/3c. In the half-open interval from warp 9 to warp 10, the exponent of w increases toward infinity. Thus, in the Okuda scale, warp velocities approach warp 10 asymptotically. There is no exact formula for this interval because the quoted velocities are based on a hand-drawn curve; what can be said is that at velocities greater than warp 9, the form of the warp function changes because of an increase in the exponent of the warp factor w. Due to the resultant increase in the derivative, even minor changes in the warp factor eventually correspond to a greater than exponential change in velocity. In the episode "Threshold", Tom Paris breaks the warp 10 threshold.
Exact velocities were given in a few episodes, one being Relativity (Season 5 Ep. 24) where Kathryn Janeway describes Voyager's velocity at warp factor 9.975. Voyager was about 70,000 light-years away from home, and crew would often use '75 years' as the time it would take to get back home at top speed. This means the Voyager series used the old method of Warp calculation. 70,000/9.975^3 is roughly 71 years. Accounting for delays to refuel, repair, restock and downtime, 75 years is a logical rounding.
A curious extension of warp travel which has been shown throughout Star Trek is the "Slingshot Effect". First discovered accidentally in "Tomorrow Is Yesterday" (1967), one of the earlier episodes of the original Star Trek series, it is a method of time travel. Whereas the actual procedure is intentionally obscure, it involved traveling at a high warp velocity (depicted in Star Trek IV: The Voyage Home to be over warp 9.8) in the direction of a star, on a precisely calculated "slingshot" path; if successful, the ship is caused to travel to a desired point, past or future. The same technique was used later in the episode "Assignment: Earth" (1968) for historic research — in this episode, the warp factor required for "time warp" is given the name "light speed breakaway factor." The term "time warp" was first used in "The Naked Time" (1966) when a previously untried cold-start intermix of matter and antimatter threw the Enterprise back three days in time. The term was later used in Star Trek IV in describing the slingshot effect. The technique was mentioned as a viable method of time travel in the TNG episode "Time Squared" (1989).
This 'slingshot' effect has been explored in theoretical physics: it is hypothetically possible to slingshot oneself 'around' the event horizon of a black hole. The result of such a maneuver would cause time to pass at a faster rate, relative to the ship within the event horizon. Such a journey would, unfortunately, be a 'one-way' trip into the future — the pilot of the craft would not have 'traveled through time' in the classical sense, but would instead have merely 'fast forwarded' through the intervening years. Travel in entropic directions other than forwards remain impossible to ascertain within the rubric of Special relativity, but the "Time Warp" drive seen in "The Cage" (TOS) may explain some of the issues.
Fans of the show and films have noted that the Slingshot involves a star, rather than a black hole, and the most normal consensus from its use concerns the nature of warp travel and warp velocities. A black hole is noteworthy for its singularity and associated event horizon, where not even light possesses escape velocity. Being able to travel at transluminal velocity would not necessarily allow escaping a black hole, as the common notion that a black hole merely possesses an escape velocity greater than c is not correct. Rather, inside the event horizon of a black hole, all paths in the space-time geometry lead closer to the singularity.
A primary component of the warp drive method of propulsion in the Star Trek universe is the "gravimetric field displacement manifold," more commonly referred to as a warp core. It is a fictional reactor which taps the energy released in a matter-antimatter annihilation to provide the energy necessary to power a starship's warp drive, allowing faster-than-light travel. Starship warp cores generally also serve as powerplants for other primary ship systems.
When matter and antimatter come into contact, they annihilate — both matter and antimatter are converted directly and entirely into enormous quantities of energy, in the form of subnuclear particles and electromagnetic radiation (specifically, mesons and gamma rays). In the Star Trek universe, fictional "dilithium crystals" are used to regulate this reaction. These crystals are described as being non-reactive to anti-matter when bombarded with high levels of radiation. Usually, the reactants are deuterium, an isotope of hydrogen, and antideuterium (its antimatter counterpart). In The Original Series and in-universe chronologically subsequent series, the warp core reaction chamber is often referred to as the "dilithium intermix chamber" or the "matter/antimatter reaction chamber", depending upon the ship's intermix type. The reaction chamber is surrounded by powerful magnetic fields to contain the anti-matter. If the containment fields ever fail, the subsequent interaction of the antimatter fuel with the container walls would result in a catastrophic release of energy, with the resultant explosion capable of utterly destroying the ship. Such "warp core breaches" are used as plot devices in many Star Trek episodes. An intentional warp core breach can also be deliberately created, as one of the methods by which a starship can be made to self-destruct.
The mechanisms that provide a starship's propulsive force are the 'warp nacelles', two (or more) cylindrical pods that are offset from the hull of the ship by large pylons; the nacelles generate the actual 'warp bubble' that surrounds the ship, and destruction of one or both nacelles will cripple the ship, and possibly cause a warp-core breach.