Stargate (device)

For lists of planets, see List of Stargate SG-1 episodes and List of Stargate Atlantis episodes.

A Stargate from Stargate SG-1.

A Stargate is a fictional portal device that allows practical, rapid travel between two distant locations. This article deals with the Stargate devices of the Stargate franchise, which first appear in the 1994 Roland Emmerich film Stargate, and subsequently carried over to the television series Stargate SG-1 and its spin-offs. In these productions the Stargate functions as a plot generator, allowing the main characters to visit alien planets without the need for spaceships or any other fictional technology.

Within the Stargate fictional universe, Stargates are large rings composed of superconductors with nine "chevrons" spaced equally around their circumference. The inner ring, which rotates within the outer, contains thirty-nine unique symbols representing star constellations. Pairs of Stargates function by generating an artificial stable wormhole between them, allowing one-way travel through. The symbols on the inner ring of the Stargate correspond to constellations and serve to map out coordinates for various destination planets. A typical Stargate measures 6.7 m (22 ft) in diameter, weighs 29,000 kg (64,000 lb), and is made of the fictional heavy mineral "naqahdah". The Stargates were created millions of years ago by an alien race known as the Ancients; their modern history begins when Egyptologist Daniel Jackson deciphers their workings in the Stargate film.

Conceptual origin

File:SG-1 True Science Wormhole.jpg

Diagram to illustrate the concept of how a stargate creates a passage to the Moon, seen in "Stargate SG-1: True Science".

The basic notion of the stargate concept is to have at least two mechanical devices (stargates) in two distant positions, such that, when active, the rings of each become similar to a physical, singular gateway or door-frame between the two locations. The concept was developed by the writers of the feature film Stargate, Dean Devlin and Roland Emmerich. Similar devices had been seen in previous fiction, but their complete conception as seen in the film was quite original — though there has been contention as to whether they plagiarized the idea from a previous script submission from a student of Egyptology named Omar Zuhdi who submitted a screenplay to them about ten years before the movie was made.

The idea of a "portal" for travelers has been seen often throughout the history of both fantasy and science fiction, often taking a similar form, a device or magical object shaped as a regular or irregular closed geometric form filled with a water-like, rippling puddle that represents the boundary point between the two locations. The stargate picks up heavily on this conception, emphasizing the "watery puddle" for the sake of an alien mystique.

The phenomenon appeared in science fiction in a radio episode of Space Patrol which aired October 25, 1952, in which it was called a "cycloplex" or a "hole in space".

Much of the inspiration for the functioning of the device is drawn heavily from theoretical astrophysics, particularly that of black holes and wormholes, a staple of science fiction, often used to create "shortcuts" through space. Although these may exist in reality, it is not widely held to be true that any such phenomenon could safely transport a human being, as such wormholes would most likely be created by excessive gravity (e.g. from a black hole) which would destroy any potential traveler. In Stargate however, this is circumvented by transporting a traveller through as an energy signature, and reintegrating him at the other end.

Surrounding plot

The Stargate film begins in 1928, when the titular alien device is first discovered and unearthed at Giza, with a young Catherine Langford watching as her father, the archaeologist who found it, directs its unearthing. Stargate SG-1 has since revealed more of the backstory of the Earth Stargate. The American ship Achilles brought the gate to America in 1939 to prevent it from falling into the hands of the Nazis. The United States Air Force then stored the device in various locations —including Washington, DC (Episode 1969)—before installing it at its location of the film and series. The Stargate was studied in the 1940s as a potential weapon and was later mothballed. As the Stargate film quickly skips to the "present day" (1994), an unsuccessful archaeologist Daniel Jackson is giving a lecture about his outlandish theories that the Great Pyramid of Giza was not built by the pharaoh Khufu. After he is laughed away, an aged Catherine Langford meets with him, and recruits his egyptological talent, taking him to a top-secret military base at Creek Mountain, where he is instructed to decipher the unique Egyptian hieroglyphs present on a set of cover-stones. He realizes that the indecipherable glyphs are in fact not words but images of constellations, such that by identifying 6 of them a position in space can be extrapolated. He is then shown the stargate itself, uses his new understanding to identify the 7^th symbol (the point of origin allowing a route to be extrapolated), and the gate is opened for the first time.

Because thousands of combinations had been previously tried and had failed, it was believed at the time that only two stargates existed, connecting Earth and the planet Abydos, which was visited in the film. At the beginning of the Stargate SG-1 series, however, a large set of additional valid coordinates were discovered engraved in ruins on Abydos. Because the coordinates pick out stars, and because time leads to stellar drift, other addresses were impossible to dial until Samantha Carter reworked the dialing system on Earth to account for this movement. After this, a massive network of possible connections suddenly became available. Even more addresses were later uncovered by Colonel Jack O'Neill from a repository of Ancient knowledge.

The alien race encountered in the original movie is later developed in SG-1 as the Goa'uld, the dominant evil power in the Milky Way. The leaders of this race, the System Lords, pose as gods and use the stargates to transport slaves between worlds. This has resulted in a large number of planets throughout the galaxy sporting human life, often in civilizations more primitive than Earth. The majority of these civilizations, descended from former Goa'uld slaves, treat the stargate as a religious relic, often as a source of long-forgotten fear and evil.

For most of the run of Stargate SG-1, Earth was under constant threat from the Goa'uld, and is no match for their superior technology. In the face of this threat, the US Air Force established a top-secret base, the SGC (Stargate Command), as a frontline defence. Multiple teams are formed and sent on missions through the stargate, their primary objective being exploration, and through it the discovery of intelligence, technology and allies to help the fight against the Goa'uld. The primary team is called SG-1, and the series follows their adventures.

For a long time it was thought that the Goa'uld were the builders of the Stargate Network, but it was later discovered that they had merely made use of the relics left behind by a different and extinct race, the Ancients. At the climax of SG-1's 6th season, Daniel Jackson discovers that the Earth myth of Atlantis is in fact founded upon the Lost City of the Ancients, and Season 7 is spent trying to locate it. At the beginning of the show Stargate Atlantis, which coincides with the beginning of SG-1's 8th season, the city is found in the Pegasus Galaxy, and 8 chevrons are dialed to send an expedition there on what could be a one-way trip. It is there that they discover a new network of stargates, and are plagued by the nemesis of the Ancients, the Wraith. During the events of The Ark of Truth it is revealed that the pre-ascended Ancient known as Amelius originated the concept of the Stargate and wormhole travel.

Internal names

The Ancients call the Stargates the "Astria Porta". The Goa'uld and the Jaffa refer to it as the "Chappa'ai" (Cha-Pa-Eye), a term also used by the human inhabitants of many worlds such as Abydos. The Wraith and some Pegasus human civilizations call Stargates "Portals". Stargates have also been referred to as the "Ring of the Gods", "Circle of Standing Water", "Doorway", "Stone Ring", "Gateway", "Annulus", "Ring of the Ancestors", "Wraith Well", "Circle of Darkness" (particularly by primitive societies that fear or revere the device), and even (in a deliberate self-parody) as "The Old Orifice".

Operation

The film Stargate rushed very quickly over how a stargate actually works and is operated, but the subsequent television shows go into this area in a great amount of detail. In SG-1, it is explained that a stargate's destination is not fixed, but is singled out by a process known as "dialing". Once a destination is selected by the traveler, the stargate generates a wormhole between itself and a complementary device at the destination, by being supplied with a threshold amount of raw energy. Objects in transit between gates are broken down into their individual elemental components, and then into energy as they pass through the event horizon, and then travel through a wormhole before being reconstructed on the other side.

Dialing

The seventh chevron in the series.

Each location served by a stargate has its own unique "address", which is a combination of seven or more non-repeating symbols appearing on the dialing stargate. By "dialing" these symbols in the correct order, the traveler selects a destination.

The show is consistent with the mechanics of address-dialing. The process involves associating a unique symbol of the inner ring to each of at least the first seven of the chevrons on the outer circumference. The main "address" is invariably dialed first, and the last symbol is the "point of origin", representing the gate being used, which acts as the final trigger for the completion of the address sequence. As each symbol is dialed, the chevron is said to "engage" or "encode" and usually responds by lighting up or moving. When the final symbol of an address is dialed, that chevron is said to "lock" and the wormhole opens (this terminology is arbitrary and often interchangeable, but preferred by the recurring character Walter Harriman). If the address is incorrect or does not correspond to an existing or otherwise functional stargate, the last chevron will not lock, and all of the chevrons will disengage.

Addresses

The SGC's Dialing Computer compiling the address of the planet Abydos.

This diagram illustrates how Stargate symbols translate to physical coordinates.

The symbols used to compose addresses are actually pictorial representations of star constellations. By identifying six constellations in space, a single point can be interpolated that corresponds to the destination desired. As only a small proportion of the possible combinations of Stargate symbols represent valid addresses, dialing the Gate at random is largely futile. In Template:Sgcite, SG-1 discovers a cartouche on Abydos with a list of valid Stargate addresses, along with a map that allows the SGC to compensate for thousands of years of stellar drift. Another list of Stargate addresses is provided by Jack O'Neill in Template:Sgcite from knowledge downloaded into his mind by a Repository of the Ancients. In Template:Sgcite, a list of Stargate addresses in the Pegasus galaxy is found in the Atlantis database. The SGC assigns designations to Stargate-accessible planets in the form Pxx-xxx (Mxx-xxx is more common in the Pegasus galaxy). Samantha Carter explains in Template:Sgcite that the designation "is based on a binary code the computer uses for extrapolation".

It is assumed by the show that this is enough to identify the position of any stargate within a galaxy. The symbols dialed are often referred to as "coordinates", and are written as an ordered string; for example, this is the address used in the show for the planet Abydos: Template:Milky Way Gate Address (corresponding to the constellations of Taurus, Serpens Caput, Capricornus, Monoceros, Sagittarius and Orion). As explained by Dr. Daniel Jackson in the movie, the stargate requires seven correct symbols to connect to another stargate. As shown in the picture opposite, the first six symbols act as co-ordinates, creating three intersecting lines, the destination. The stargate uses the seventh symbol as the point of origin allowing one to plot a straight line course to the destination.

Eight-symbol addresses were introduced in Template:Sgcite, opening up new plot lines by connecting stargates to different galaxies. The additional symbol acts as a type of "area code". Such connections, in comparison to seven symbol codes, required substantially more energy to complete a functional wormhole — much more than any standard dialing method can provide. Opening an intergalactic wormhole has been shown to require large amounts of power compared to an interstellar wormhole. This has been generated in a variety of ways in different episodes, although the main way is using a Zero Point Module (ZPM).

The show has never featured a nine-symbol address, so the purpose of the ninth chevron is unknown. However, Robert C. Cooper has stated that the purpose of the ninth chevron will be revealed in the upcoming series, Stargate Universe. One of the purposes proposed for the new series is that the ninth chevron connects it with an Ancient ship that seeds stargates throughout the universe, and was abandoned after the ancients ascended. It is unknown if this will be the final idea.

Dial-Home Device

"DHD" redirects here. For other uses, see DHD (disambiguation).

The Dial-Home Device

There are a handful of methods used in the shows to dial a stargate, and the most common is with the use of a Dial-Home Device. Almost always referred to as the "DHD" for short, it is depicted as a pedestal-shaped device with a round inclined control panel on top, consisting of two concentric circles of "keys", and a translucent red (Milky Way) or blue (Pegasus) hemisphere in the center; the keys represent the symbols on the rim of the stargate. By pressing these keys a traveler builds an address. The central hemisphere serves as an "Enter" key to activate the stargate once a destination has been dialed.

In the Milky Way, the Dial-Home-Device contains 38 of the 39 symbols on the stargate, meaning there is always a missing glyph on each DHD. This missing glyph however is not the point of origin for that planet. It has been confirmed that the missing glyph on numerous DHDs differs on each planet because of that planet's stargate position in the galaxy. In other words, it acts as a default setting to prevent bad connections to obstructed stargates in the Milky Way. The glyph that is hidden under the pedestal of the stargate, unseen along with the extra two chevrons, cannot be dialed by that stargate's DHD. This states that only certain addresses can be reached in certain positions in the galaxy. The only way to intervene and reach all destinations in the Milky Way is to manually dial the gate, or use an alternative dialer, such as the one at the SGC.

File:Atlantis DHD.jpg

DHD panel in Stargate Operations at Atlantis

Milky Way puddle jumper DHD console.

The Atlantis DHD is more similar to the Earth's dialing computer than an actual DHD, and looks more like a set of crystal panels. It can block out certain gate addresses. The Atlantis DHD also has an extra control-crystal allowing the dialing of an eighth chevron during the dialing sequence and is the only DHD in the Pegasus Galaxy capable of dialing Earth. A similar DHD is also used on Puddle Jumpers, where the set of used glyphs corresponds to the galaxy of the Puddle Jumper. The Wraith also travel through Stargates in small spacecraft called darts and have some means of remote-dialing them in a manner similar to Ancient ships. According to Dr. Zelenka, dialing an address leaves a small imprint on the control crystals of the DHD, and about fifty addresses can be recovered from a DHD using the proper equipment. However, this gives no indication of the order in which the addresses were dialed, and no guarantee can be made as to the accuracy of the recovered addresses.

The show makes it clear that every stargate originally had its own DHD, located directly in front of the gate and facing it. Over time, however, some DHDs have been damaged or lost. This has been the source of plot-difficulties for the protagonists on several occasions, as it is still possible to travel to a stargate that lacks a DHD, meaning that dialing home again will be much more difficult, if not impossible. One of the primary functions of the MALP that precedes an SG team is to confirm the presence of a DHD. In the absence of a DHD, a user must manually select the address through sheer force (as in physically rotating the rings on the Stargate) and an external power-source. Pegasus Galaxy Stargates do not have a movable ring, so manually dialing these is impossible. Travelers can also emulate a DHD through a Dialing computer like Stargate Command has. Remote dialers have been used by several races like the Goa'uld and Asgard in various episodes.

The Wormhole

Side-on view of a stargate as an unstable vortex is ejected.

Once an address is dialed, the gate is said to have created a "stable wormhole" between itself and the gate dialed. The creation process is depicted with great consistency, and hence has become one of the defining motifs of Stargate, at times being central in both the SG-1 and Atlantis title sequences. It involves the generation of the "puddle of water" portal which lasts roughly 2 seconds, and is completed by the ejection of an unstable energy vortex resembling a surge of water or quicksilver. The vortex is portrayed as a symbol of the stargate's power, invariably causing characters to be awed. Any matter which comes into contact with the vortex is annihilated on a molecular level, as is dramatically demonstrated by a pair of smoking shoes in the episode "Prisoners". This aspect has been used in some cases to dispose of highly hazardous materials.

The actual portal of a stargate appears inside the inner ring when an address is correctly dialed. This has the appearance of a horizontal puddle of water which represents the "event horizon" in the show. In non-fictional parlance, an event horizon is the perimeter around a black hole or wormhole beyond which the gravitational pull of the singularity would be too strong to overcome. The wavering undulations characteristic of water are supposed to represent the "fluctuations in the event horizon". This puddle may then be entered (usually accompanied by a water-like sound), and the traveler will emerge from a similar pool at the destination stargate.

The show makes it clear that transit is strictly one-way; an attempt to travel "backwards" causes the traveler to be destroyed (though during the episode Template:Sgcite and in the first episode a man partially puts his hand through the event horizon of the destination gate and pulls it back with no apparent issues However, as matter is only transmitted through a stargate once the whole object has passed the event horizon (except in the same "A Hundred Days" episode where Teal'c dangled from a rope secured to a ceiling on the other side) the stargate would not have started to try to deconstruct him, instead waiting until he was entirely inside). Additionally, the outgoing gate is invariably entered from the same side as the unstable vortex present during stabilization of the wormhole.

Original wormhole travel from the Stargate movie.

File:New wormhole.jpg

An en-route wormhole visual effect, from late SG-1.

Passage through a Stargate's wormhole is depicted as a visual effect of shooting through a tunnel in space, although this is just a visual aid as travelers are not conscious during the trip. The average travel time between Stargates is 6 seconds. In the movie and early SG-1 episodes, travelers exit from the Stargate "frozen stiff" and feeling as though they have been on a "roller coaster ride". The character Charles Kawalsky describes Stargate travel as like pulling "out of a simulated bombing run in an F-16 at eight-plus g". In later episodes the experience is no different than stepping through a door, explained as a result of refinements made in the Stargate interface at the SGC.

Under normal circumstances, a wormhole can only be maintained for slightly more than 38 minutes. Extending the wormhole duration beyond this requires tremendous amounts of power, such as that provided by a nearby black hole,, energy beings, or advanced technologies.

While the kawoosh effect in the movie was created by filming the actual swirl of water in a glass tube, and looked like a vortex on the back of the Gate, however on the TV series, this effect was completely created in CG by the Canadian visual effects company Rainmaker. At the beginning of Season 9, the original movie wormhole sequence was substituted by a new sequence similar to the one already used on Stargate Atlantis, but being blue as it was in the movie and SG-1, whereas in Atlantis it's green.

Throughout the run of the television franchise, it cost $5,000 to show a person stepping through the event horizon, using visual effects.

Known statements about wormhole physics

As portrayed in the fictional universe of Stargate, wormhole physics is a field of study that describes the functioning of stargates and wormholes. It was pioneered by Samantha Carter. In the episode "Upgrades", possessing super-human abilities Samantha Carter wrote an entire book on the subject, claiming she had been wanting to write it for a long time previously but had never been able to find the time as it was such an incredibly complex subject.

• Energy to maintain an established wormhole can come from either side, though the energy to form a wormhole can only come from the dialing stargate.
• Substantial gravitational force can pass through a wormhole from either side. (i.e. the effects of a Black Hole).
• Outgoing wormholes can be affected by exterior gravitational and electromagnetic forces, causing them to connect to stargates other than their intended targets.
• When traveling from one gate to another, exterior forces such as solar flares can cause the wormhole to connect to a stargate in another time period. In this case, the wormhole will then sometimes, under some unknown circumstances, connect to the source stargate. (to source gate: "1969" and "2010", to another gate: "The Last Man", "Stargate: Continuum").
• Matter can only travel one way but weak energy such as radio communication can travel both ways through a stargate. This can be explained by the hypothesis that the diameter of the wormhole is very small, possibly microscopic in size. Energy would have no problem passing through on its own but matter would need to be converted into energy and then re integrated at the other side.
• Artificial wormholes created by stargates can only stay open for up to 38 minutes without an extremely powerful energy source powering the dialing gate. Such as "an infinite amount of ZPMs or a Black Hole." (Dr. McKay, "First Strike").
• Wormholes are also possible without the use of a stargate as demonstrated in the Stargate Atlantis finale Enemy at the Gate, however it is not gone into depth how this is possible or what limitations there are to this technology. The Ancient city-ship Atlantis used this method of wormhole travel to travel from the outside edge of the Milky Way galaxy to Earth in just a few seconds.

Complexities of function

Both Stargate SG-1 and Stargate Atlantis introduce complicated facets of stargates to contrive more interesting plotlines. Some of these have been developed into integral parts of how stargates function.

Matter transmission

Stargates only transmit entire objects at a time. Matter from an object that is only partially through the event horizon is stored in a "hyperspatial buffer". Until an object is completely through, it can still be pulled back out of the event horizon. Matter inside a buffer is effectively held in stasis. The buffer is normally wiped clean after the wormhole disconnects, at which time any matter still stored inside ceases to exist. The exception to this is if the wormhole is terminated artificially with an object already en route, in which case it remains stored in the buffer of the receiving Gate until the next wormhole connection. In such a circumstance, the object can be rematerialized by establishing an event horizon without opening a wormhole, done by removing the control crystal of the DHD. Kinetic energy is conserved through a wormhole, so an object will exit a Stargate at the same speed at which it entered. A Stargate is able to discern whether something is "trying" to pass through as opposed to pressure from its ambient environment. Thus, active Stargates in an atmosphere or underwater do not allow gas or water molecules through.

Gate obstruction

A Stargate being excavated.

A wormhole is prevented from forming if a significant obstruction is present inside the Stargate's ring. Consequently, a simple way to seal a Stargate is to bury it, as was done to Earth's Giza Stargate. Another way of controlling travel through a Stargate is by placing a barrier just above the event horizon, which will prevent incoming matter from being reintegrated (essentially annihilating it). The Iris at the SGC and the Gate shield at Atlantis function in this way. These barriers also prevent the formation of the unstable vortex, although radio communication is still possible.

Power source

Power is always required to establish an outgoing wormhole, and is usually supplied by the DHD, but any stargate can receive a wormhole whether it has a power supply or not; the dialing gate is the one that supplies power to both. In a few cases, stargates have been dialed "manually" when more sophisticated means were not available. This was accomplished by providing sufficient raw power to the gate and then rotating the symbol ring by hand to encode each chevron. Power can be fed directly into the Naqahdah that composes the gate; power harnessed from lightning strikes has been shown to be sufficient. The stargate that establishes an outgoing wormhole determines how long the wormhole is held open, and can generally close the wormhole at will. Under some conditions, a gate only needs enough power to connect briefly, then the receiving gate can provide enough power to maintain the connection. The same is true if the outgoing gate loses power while transmitting; if the incoming gate has a DHD, it will take over powering the gate until reintegration is complete. The System Lord Anubis possessed an Ancient weapon that would channel energy into a receiving stargate through an open dialed gate; prolonged use of this weapon would cause the gate's Naqahdah to continue to absorb the energy until a significant explosion would take place.

Secondary gates

Some planets are known to possess "secondary" or "backup" stargates. The second stargate is normally inactive, with the primary stargate (defined by the presence of a functioning Dial-Home Device) receiving all incoming wormholes. If a stargate experiences a power surge while an outgoing wormhole is open, the other end of the wormhole has been observed to "jump" to the next closest gate in the network. (The effect can also be used as a defensive measure, as seen in the episode "Prototype" or to close a connection with the receiving stargate as demonstrated in the episode "A Matter of Time"). In the case of a planet with two gates, the closest is the inactive secondary gate. This scenario occurred in SG-1's first season, and resulted in a second gate being discovered on Earth, located beneath the ice of Antarctica.

The Antarctic gate was later revealed to have originally been the primary stargate on Earth, built by the Ancients. It could in fact be the first stargate ever built. The stargate originally used in the SGC, found in Giza, was brought to Earth, by Ra, from another planet. Since stargate addresses correspond to planetary locations and not individual gates, the new gate inherited the same address as the one in Antarctica. Because the Antarctic gate had been abandoned millennia earlier by the Ancients and no longer had a connected DHD, Ra's gate became the primary.

In the episode "Nemesis", SG1 transports the stargate from Stargate Command onto a crashing spaceship in order to escape. The gate is replaced at the SGC by the Antarctic gate. The original gate survives the crash, however, and the Russian military takes possession of it to conduct their own off-world travel. Because they were also in possession of a DHD (not found in the original Giza dig but recovered from Germany after WWII), which they activated and deactivated at pre-defined times, they were able to selectively become the primary gate. Using a strict schedule for returning teams, they were able to avoid detection by the US Air Force for some time.

In Redemption, the second stargate was destroyed by Anubis. In order to continue their stargate program, the US Air Force took on loan the Giza stargate from the Russians at a hefty price, and this gate is now the only one left on Earth. This stargate was eventually traded from the Russians for the Korolev.

In the episode, "Enemy at the Gate", it is revealed that Pegasus galaxy stargates supersede the older, more outdated stargates, such as the one on Earth. Earth was unable to dial out from the SGC when the Wraith "Super-hive" ship was in orbit around the moon with its own Pegasus stargate; the programming of the newer gates force it to take precedence over incoming wormholes to the older outdated stargates, and thus, disabled the Earth gate at the SGC from dialing out. A similar situation was encountered at the Midway Station with the Milky Way and the Pegasus gates.

Durability

Stargates are very durable; the oldest in the Milky Way is probably the Antarctic Gate, 50 million years old; the power source may have been younger.

The stargates themselves are extremely resistant to damage or destruction: in one case, a stargate survived a direct hit from a meteor, whilst another was still capable of creating a stable wormhole while on a planet near a newly-formed black hole. A stargate has also been seen to continue functioning whilst entering a star, though it was protected by a portable forcefield for a portion of its journey. In the SG-1 fourth season episode "Chain Reaction", the SGC sent a naqahdah-enhanced nuclear bomb to a planet whose surface had trace amounts of naquadah in its topsoil; the explosion destroyed the entire planet, yet the gate still remained open and intact.

In the ninth season of Stargate SG-1 the United States develops a naqahdriah-enhanced "Gatebuster" nuclear bomb that is theoretically capable of destroying a stargate (the "Mark IX"). However, when it was first used it failed to destroy the intended stargate, as an Ori shield defending the gate was being powered by the weapon attacks attempting to destroy it.

A later attempt was made in the episode "The Shroud" against another stargate in the Pegasus Galaxy with a Mark IX warhead however was successful in destroying an active stargate by placing the bomb behind the gate so that the energy would not be absorbed by the open wormhole.

Susceptibility

The stargate and its network is susceptible to computer viruses. In the episode "Avenger 2.0" the entire stargate network is brought down by a virus created by Dr. Felger. Although not intentional the virus was altered by Ba'al to take the network down. It was previously unknown that each DHD does periodic correlative updates by dialing other gates in close proximity to one another. The updates were designed to compensate for stellar drift to thus maintain the proper coordinates. The stargate at the SGC uses a human developed "Dialing Computer" rather than a DHD which accounts for the lack of in depth knowledge regarding the DHD's. It is also what saved the network as the Earth stargate was the only gate unaffected by the virus because it has no DHD. Stargates are also susceptible to a precise form of subspace interference which causes active stargates to build up energy until they explode vaporizing much of the surrounding area for a significant distance. To date the only known source of the interference is the Ancient Attero device, which created it as a side effect to its primary purpose and has since been destroyed.

Other uses

In several episodes of the series, the Stargate Network was used for a purpose other than interplanetary travel. In the plots in which these extra functions feature, they are almost always discovered by a fluke, and were not intended in the design of the stargates. Two such occurrences regard the stargate's interaction with time, such as "1969", in which the SG-1 team accidentally travels backward in time to the year 1969, as a result of the matter transmission stream passing through a solar flare. The character Samantha Carter intentionally uses this phenomenon in the episode "2010", where she uses advanced technology to predict a flare and send a message back in time. Time is also a factor in the episode "Window of Opportunity", when a scientist uses a failed time machine built by the Ancients to isolate a region defined by 14 stargates from the rest of the space-time continuum, causing a time loop.

In several episodes, the stargate, and the cobbled-together dialing program utilized by the SGC, are nearly the cause of disaster. In the episode "Red Sky", the bypassing of a system error caused the stargate to introduce atoms of plutonium into the center of a star, causing the star to become unstable. In the episode "Ripple Effect", an unknown device and/or method was used to connect different realities and was reversed by use of an Asgard beam weapon.

Later in Stargate SG-1 a feature of the Stargate Network, whereby one stargate can be caused to dial multiple other gates simultaneously, is revealed. This allows a blast wave such as that of the Dakara Superweapon to extend almost indefinitely throughout the galaxy, as seen in "Reckoning".

In the episode Template:Sgcite, a stargate was used as a weapon capable of destroying an entire solar system. The gate was dialed into a planet in close proximity to a black hole. The gate (protected by a force field) was then sent into a star. The resulting loss of mass caused the sun to go supernova, destroying the solar system and Apophis's fleet, which was orbiting the star at that time.

Features

Stargates are all held to be made of the fictional heavy mineral "Naqahdah", an immense superconductor which is also extremely durable. Milky Way stargates are held to be 64,000 lb (29,000 kg) (32 Tons) in weight.

Milky Way

File:Stargate SG-1 Gates.png

Schematic diagram of a Milky Way stargate with glyphs

A Milky Way stargate has 39 inscribed symbols on the inner ring. When dialing, this inner ring rotates until the dialed symbol is aligned with the seventh chevron, at which point the ring pauses, the seventh chevron moves down and up, and the appropriate chevron in the sequence engages. In the Stargate SG-1 series, an engaged chevron glows red. In the original Stargate film, all of the chevrons use this motion, and none of them glow red.

With 38 symbols, the Stargate Network in the Milky Way has:

(38×37×36×35×34×33) = 1,987,690,320 possible 7-symbol addresses,

63,606,090,240 possible 8-symbol addresses and 1,971,788,797,440 possible 9-symbol addresses.

However, not all points in space represented by these addresses have stargates, in fact, there are sufficiently few valid coordinate sets that randomly dialing the stargate is largely futile. If the person dialing does not know the point-of-origin symbol, there are many more possible combinations.

Because the gate on Earth was found without a DHD, the stargate team on Earth developed the technology to interface with the gate in order to power it and dial it by the use of computers. (This is essentially an automated version of 'manual dialing'.) When using a DHD, however, each chevron is activated immediately upon entry of the symbols, without the inner ring spinning. This allows for a much faster dialing process.

Symbols at Giza

As mentioned in the original film, the symbols on the Giza Stargate correspond to constellations as seen from Earth, except for the point of origin symbol. The SG-1 season 7 finale Template:Sgcite reveals that each symbol has a corresponding syllable in the Ancient language, so that Gate addresses can be spoken aloud.

Position	Glyph	Constellation	Position	Glyph	Constellation	Position	Glyph	Constellation
1		Origin symbol†(Earth)	14		Microscopium	27		Taurus
2		Crater	15		Capricornus	28		Auriga
3		Virgo	16		Piscis Austrinus	29		Eridanus
4		Boötes	17		Equuleus	30		Orion
5		Centaurus	18		Aquarius	31		Canis Minor
6		Libra	19		Pegasus	32		Monoceros
7		Serpens Caput	20		Sculptor	33		Gemini
8		Norma	21		Pisces	34		Hydra
9		Scorpius	22		Andromeda	35		Lynx
10		Corona Australis	23		Triangulum	36		Cancer
11		Scutum	24		Aries	37		Sextans
12		Sagittarius	25		Perseus	38		Leo Minor
13		Aquila	26		Cetus	39		Leo

^†This symbol is unique to the planet earth. In the movie, Dr. Jackson interprets it as representing the Sun over the peak of a pyramid. Other planets are described as having their own unique origin symbols.

Pegasus galaxy

File:Stargate Atlantis Gates.png

Schematic diagram of a Pegasus Galaxy stargate with glyphs.

An orbital Stargate in the Pegasus galaxy.

In the spinoff series Stargate Atlantis, an expedition dials the 8-symbol address Template:Milky Way Gate Address from Stargate Command to travel to the Ancients' Lost City of Atlantis, located in the Pegasus galaxy. They find that the Ancients seeded planets throughout the Pegasus galaxy with Stargates too. Pegasus Stargates have a slightly different design than those in the Milky Way, though the differences are mostly cosmetic. One functional difference is that Pegasus Stargates do not have a rotating inner ring, meaning that they cannot be dialed manually. The alternative Stargate design in the Pegasus galaxy is one of many things the producers of the shows employed to differentiate between SG-1 and Atlantis. Another important difference is that Pegasus Gates supersede Milky Way gates when in close proximity, this is possibly due to them being a newer model that those used in the Milky Way. This was demonstrated in the Stargate Atlantis finale "Enemy at the Gate" where a Wraith Super-Hive with a Pegasus Gate orbiting Earth, became the dominant Stargate and so intercepted all travellers heading to Earth which used an older Milky Way gate.

Pegasus Stargates contain 36 symbols as opposed to the Milky Way's 39. Seven symbols are still required to dial an interplanetary address, adhering to the same constraints as a Milky Way gate. With 35 symbols, the Stargate network in the Pegasus galaxy has:

(35×34×33×32×31×30) = 1,168,675,200 possible 7-symbol addresses,

33,891,580,800 possible 8-symbol addresses and 948,964,262,400 possible 9-symbol addresses.

The only Stargate in the Pegasus galaxy capable of reaching Stargates in the Milky Way is the one in Atlantis. This is due to a special "control crystal" in the Atlantis DHD, without which a Pegasus Stargate cannot encode its eighth chevron. The crystal is not restricted to be used only in that particular DHD, as in Home, the crystal was temporarily removed and installed into the "normal" DHD of M5S-224 by McKay.

Some Pegasus Stargates are placed in geosynchronous orbit around a planet (sometimes called "Spacegates" in the show) rather than on its surface, something that has never been seen in the Milky Way. Ships such as the Ancient puddle jumper and the Wraith dart are designed to fit through Stargates, and have built-in DHDs. Orbital Stargates are kept in place by the three station-keeping nodes or thrusters placed equidistantly around the circumference. They are seen in the SG Atlantis season 5 episode Ghost in the Machine where they automatically realign a stargate that has been hit by a puddle jumper.

Symbols at Atlantis

The symbols depicted on the Atlantis gate again correspond to constellations, although in this case the constellations are fictional. The Atlantis glyphs do have names, as seen in a shot of McKay's laptop in the episode "Sateda".

Position	Glyph	Constellation	Position	Glyph	Constellation	Position	Glyph	Constellation
1			13			25		Rdehi
2			14			26
3		Alura	15			27
4			16			28
5			17			29
6		Ecrumig	18			30
7			19		Subido (point of origin for Atlantis)†	31
8			20		Salma	32		Gilltin
9			21			33
10			22			34
11			23			35
12		Arami	24			36

^†As with SG-1, this origin symbol is unique to the stargate at Atlantis, and other stargates have their own unique origin symbols as well. Atlantis has since been moved; it is unclear if this has changed the origin symbol, since it is a constellation rather than an abstract as it is on SG-1.

Universe

File:Stargate Universe Gates.png

Schematic diagram of a Destiny's stargate with glyphs

Not much is known about the model of Stargate used in the upcoming series, Stargate Universe. A brief glimpse of the Stargate was seen in the first teaser of the show. In a later teaser, it was shown that the entire gate spins.

Destiny Stargate contain 36 symbols like Pegasus Stargates.

Symbols at Destiny

Position	Glyph	Position	Glyph	Position	Glyph	Position	Glyph
1		10		19		28
2		11		20		29
3		12		21		30
4		13		22		31
5		14		23		32
6		15		24		33
7		16		25		34
8		17		26		35
9		18		27		36

Other variants

File:Mini gate.jpg

Orlin's makeshift Stargate.

• Orlin's Stargate In the Stargate SG-1 episode "Ascension," the outcast Ancient, Orlin, builds a miniature Stargate in Samantha Carter's basement. Its stated components included 100 pounds of pure raw titanium, 200 feet (61 m) of fiber optic cable, seven 100,000 watt industrial strength capacitors, and a toaster. This gate was hooked up to the main power supply of the house and only connected once, to Velona, before burning out.
• Tollan Stargate In "Pretense", the advanced Tollan civilization is shown to have a new Stargate, built with the assistance of the Nox. Jack O'Neill sarcastically mocks the Tollan gate, saying "Ours is bigger". The Tollan Stargate is destroyed by the Goa'uld in "Between Two Fires".
• Ori "Supergate" (main article) In the ninth season of Stargate SG-1, the Ori were introduced as the new main enemy for the show. The Ori employ extremely large Stargates to move their fleet of warships from their home galaxy to the Milky Way. Dubbed "Supergates", these devices are composed of 90 individual segments and are powered by a quantum singularity.
• McKay-Carter Intergalactic Gate Bridge (main article) Introduced in season 3 of Stargate Atlantis, the Gate Bridge is a chain of Stargates placed between the Milky Way and the Pegasus galaxies, allowing movement between Atlantis and Earth without the need for a ZPM or the Daedalus. Halfway along the Bridge is Midway Station, where travelers switch from one galaxy's gate system to the other. The Bridge is hijacked by the Wraith in the episode Template:Sgcite, and the Midway Station is destroyed as a result of Wraith tampering in the control systems. As a result of the destruction of the Midway Station, the gate bridge has since become inoperative.
• Asuran satellite weapon (main article) In the Stargate Atlantis season 3 finale, "First Strike", the Asurans send a satellite weapon to attack Atlantis in response to the Apollo's bombing of their homeworld. The weapon consists of an eight-chevron Stargate, hyperdrive, shield, and a navigation system. Once it reaches its target, the Stargate activates and the Asurans fire an energy beam through.

Making of the props

Two full stargate props were originally built for the SG-1 pilot Template:Sgcite, the second of which was reconstructed from the prop used in the film. They are made of steel and fiberglass, and are 22 feet (6.7 m) in diameter. The second prop is less detailed, and is used for exterior scenes; in the pilot it was used solely on the planet Chulak. The primary one, however, is quite sophisticated. It is fully automated, and capable of rotating and emitting light. This is achieved by the use of a specially-designed 22-foot (6.7 m) circular gear, which turns the inner ring on a precise pinion drive wheel, using an eight horsepower electric motor. The top seven chevrons emit laser pulses which are read by a sensor fed into a computer responsible for the gate's movement, which is consequently able to start and stop the rotation very quickly. This main prop is kept almost immovably at the permanent set of the SGC, at Bridge Studios, Vancouver.

There are further stargate props which are no more than two-dimensional or semi-three-dimensional (jar-lid shaped) stargates, being more lightweight and easier to erect on location. These are always filmed front-on to preserve the illusion. If a shot involves the iris, this is added in post-production, as the mechanics of it opening and closing would be very difficult to build. However, when a stargate is filmed with just a closed iris (i.e. without it moving), a tangible prop is inserted into place.

The visual effects for Stargate SG-1 and Stargate Atlantis are predominantly produced by Rainmaker Digital Effects, a notable visual-effects studio. However, some effects, including the entire Ori battle sequence in the episode Template:Sgcite, were done "in-house". The unstable vortex effect, both in the film and the early seasons of the series, on account of being "difficult to achieve" was generated only once and recorded from various angles; this recording was the same used for all gate opening shots early in the series. Rather than being a jet of water, it is actually the image of high-pressure air being blasted into a tank of water. The effect was achieved by mounting a jet airplane engine two feet above a water tank, and using its 180 mph (290 km/h) windstream to create the sufficient water displacement. In post production, the surrounding water was removed with computer editing, and the image of the air-jet pasted into the center of the opening stargate. This technique was only used for earlier episodes, and the effect was replicated digitally soon after to allow more flexibility in shots.

To cut down on costs, the opening of a stargate is often just implied rather than shown, by a costless sound-effect followed by distinct lighting effects characteristic of light shining through water (as the event horizon is depicted). The DVD commentary for Stargate SG-1 explains that these effects are produced by reflecting light off large sheets of vibrating Mylar.

The stargate itself is nearly always filmed against a blue or green backdrop, not only making it easier to paste the vortex imagery onto the scene, but also facilitating the superimposition of the "event horizon ripple effect", which is entirely computer-generated. However, if a shot only involves an open wormhole without anyone stepping through it, the crew may choose to use a "practical puddle," which is simply a back lit screen placed in the gate displaying a video of the wormhole effect. This only works, however, on a darker set, as otherwise the projection will get washed out. On occasion, the stargate itself is also completely swapped out for a computer generated model, usually in cases where it is being moved, or is depicted in space. Series producer Robert C. Cooper explained that it often costs a lot to erect a stargate on location, and so in some cases offworld gates are also entirely a visual effect.

Use of the term "stargate" in other works

The basic concept of a "stargate" did not originate with the movie Stargate. Andre Norton's 1958 novel Star Gate used the term, while the portal concept is a key plot device used in science fiction for decades prior to the film.

Since the introduction of the stargate on the big screen, authors Lynn Picknett and Clive Prince wrote The Stargate Conspiracy: The Truth About Extraterrestrial Life and the Mysteries of Ancient Egypt. The book details an alternative theory which associated the term stargate with Egypt's past: either the pyramid itself is a gateway to the stars (because of the shafts pointing to a star) or the building of Heaven on Earth based on geographical location of the great and outlying pyramids (see: Orion).

• In the novel of the same name (by Stephen Robinette) the eponymous stargate the protagonist was hired to complete after its designer died in an accident was reminiscent of the Ori "Supergate". Miles across and constructed in space a safe distance from earth, it could reach out and snatch a chunk of a distant world the size of Los Angeles, expelling it into space to be mined for valuable elements.
• In the film and novel of the same name 2001: A Space Odyssey the monolith orbiting jupiter appears to invert, becoming a 'star gate' sending David Bowman to a different star system far from the milky way; as Bowman is drawn into the gate his final comment heard on earth is "My God—it's full of stars!"
• In the Marvel Comics Universe, the alien Shi'ar have a network of "stargates" to aid in interstellar travel.
• The TV show Buck Rogers had devices called 'stargates', however, they aided in interstellar travel. They were more similar to jumpgates from the TV show Babylon 5.
• Two episodes of the television series Jason of Star Command featured an obelisk-like teleportation device called a "stargate," which functioned as a "portal to another universe."
• In the arcade game Stargate a.k.a. Defender Stargate and Defender II, the stargate is represented by a series of concentric rectangles and takes the player's ship to a humanoid being abducted, warp ahead levels in the game, or just halfway across the world.
• The computer game Galactic Civilizations II: Dread Lords mentions the use of stargates as a means of travel between the stars for space ships. The stargates became obsolete when humans invented Hyperdrive.
• In the computer game Master of Orion II the Star Gate is a late game technology (upgrade from Jump Gate) that allows starships to travel instantaneously (one turn) between all the colonies owned by the player in the galaxy, regardless of distance.
• In the MMORPG Eve Online stargates are used to jump between star systems, more primitive "Acceleration Gates" (which modify a ships mass and boosts it's inertia) are can be used for in system travel
• In the online game Planetarion, one level of research used to increase the speed of ships/fleets is titled 'stargate'.
• In the anime television series Cowboy Bebop, large devices called astralgates link the habitable planets, moons, and asteroids of the Solar System, facilitating travel in space vessels.
• In the computer game Starcraft, the alien Protoss use structures called stargates to bring space ships from staging areas to the battlefield. A similar structure called a gateway is used for troops.
• In the animated series Super Friends: The Legendary Super Powers Show, villains Darkseid, Kalibak, Desaad, and the Parademons used what were referred to as "stargates", a version of the "Boom Tube", which was a mode of interdimensional transportation frequently used by the New Gods, a pantheon which included the above characters and were featured in DC Comics' "Fourth World" titles. The 1986 Legends miniseries trade paperback collection also refers to them as such.
• In the ReBoot episode "When Games Collide" Megabyte creates a portal generator resembling the Stargate. In the later episode "Daemon Rising" it is revealed that the design came from Welman Matrix in his attempt to contact other systems in cyberspace.
• In the Aqua Teen Hunger Force episode "Universal Remonster", Emory and Oglethorpe travel across spacetime through the "Fargate" (a thinly-disguised copy of the Stargate) to steal the Aqua Teens' cable. In order to control which channel they watch, they use the Universal Remonster, a small robot made of several remote controls and shaped like a small werewolf that accidentally ends up in the hands of Master Shake, who uses it to torture Meatwad. During the episode, Master Shake and Frylock find the Fargate under the house.
• In the South Park three-episode "Imaginationland" arc, a replica of the Stargate is seen being used by the US government as a doorway to the imagination. The government even goes so far as to name Kurt Russell commander of the first troops sent through, since he "starred in the movie that was sort of like this."
• DC Comics' character's the Legion of Super-Heroes use stargates to travel around the United Planets. It was due to a malfunctioning Stargate that the Legion got lost on the other side of the universe. Stargates appeared in the Legion cartoon series episode 'Brain Drain' though they were not named as such. They are used here to transport inanimate cargo around the universe. Before using the device the team are warned it could kill organics that used it.

See also

• Technology in Stargate
• Stargate SG-1
• Stargate Atlantis
• Stargate Universe
• List of Stargate SG-1 episodes
• List of Stargate Atlantis episodes
• Portals in science fiction