Stargate is one name for a class of fictional devices which allow instantaneous travel between places.
This article deals with the Stargates that feature as a central part of stories set in the Stargate science fiction universe. They are uniformly depicted as large, usually vertical metal rings. In the stories, their function is to transport people or objects across the vast distances of space by creating a stable artificial wormhole connected to another stargate.[1]
They first appeared in the 1994 film Stargate, directed by Roland Emmerich, and then were redesigned to subsequently appear in the television series Stargate SG-1 and its spinoff Stargate Atlantis (as well as the animated series Stargate Infinity).[2] The Stargate is the central plot generator of these productions, allowing for stories focused on a small team of protagonists exploring other planets and meeting other races on foot, rather than the more prevalent, grandiose "space opera" of interstellar starships seen elsewhere in science fiction.
In the fictional Goa'uld language, the stargate is referred to as the Chappa'ai (Cha-Pa-Eye). This word for the gate is also used by many of the inhabitants of the Stargate worlds, no doubt brought to them by the Goa'uld System Lords. The Gates have also been referred to as the "Ring of the Gods", "Circle of Standing Water", "Doorway", "Stone Ring", "Annulus", "Ring of the Ancestors" and "Portal" (by characters of less advanced societies that fear or revere the device), and even (in one instance) as "The Old Orifice."[3]
Stargates are marked out by nine chevrons spaced equally around their circumference (See the Schematic diagram below), and 39 symbols displayed on an inner ring on gates in the Milky Way Galaxy, or 36 on those in the Pegasus galaxy (it is unknown how many symbols feature on gates in the Ori home galaxy or on those in Ida) .[2] They are typically 22 ft (6.7 m) in diameter, 64,000 lbs in weight,[4] and held to be made of the fictional heavy mineral "Naqahdah". The gates are almost always seen standing vertically.
In the mythology of the canon, their creators were an alien race known as the Ancients,[2] who called them the Astria Porta in their language, and scattered them on a variety of planets and moons, throughout the Milky Way and other galaxies millions of years ago. In "The First Commandment", Teal'c stated that many were later terraformed by the Goa'uld.[5] Collectively, these comprise what is called the "Stargate Network", as they facilitate interaction between distant planets. The plot of Stargate effectively begins when the United States Air Force discovers how to use one of these devices that was discovered on Earth and begin to explore the galaxy through its use.[1] Although Stargates are present on many planets, most of the races they encounter are relatively primitive, and view the gates as no more than divine, sacred or terrifying relics, as evidenced by such names as "Ring of the Gods" and "Circle of Darkness".[5][6][7]
Conceptual origin
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.[8]
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.
A lot 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,[9] as such wormholes would most likely be created by excessive gravity (e.g. from a black hole) which would destroy any potential traveler.[10]
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. It quickly skips to the "present day" (1994), in which 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 7th 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.
Internal names
The Ancients placed Stargates on thousands of worlds across the galaxy, but the gate network was open to use by all, and continues to be a convenient form of travel for many races. Some races, such as the Goa'uld, grew their ways of life around the gates, which became integral to the functioning of their culture.
In turn, most races developed their own names for the Stargates. The Ancients called them Astria Porta, a Latin-esque word for "Star Gate"; in Latin, it would really be either porta stellae or porta in astria. The Goa'uld and Jaffa, call them the Chaapa'ai. The English word "Stargate" is a direct calque of Chaapa'ai, and Chaapa'ai is itself a calque of Astria Porta.
Although Stargates are present on many planets, most of the races which inhabit them are relatively primitive, and view the gates as no more than divine, sacred or terrifying relics, as evidenced by such names as "Ring of the Gods" and "Circle of Darkness".[5][6][7] In the Pegasus galaxy, villagers know them as Rings of the Ancestors and variations thereof. They are also commonly referred to as "the ring", "the annulus", or simply "the gate".
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".[11] 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.[12] 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.[1]
Dialing
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.[13][11] 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 chevron on the outer circumference. The main "address" is invariably dialed first, and the last symbol being the "point of origin" " representing the gate being used, which acts as the final trigger for the completion of the address sequence.[14] 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).[14] 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.[12]
Addresses
The symbols used to comprise addresses are actually pictorial representations of star constellations. By identifying six constellations in space, a single point can be extrapolated that
corresponds to the destination desired.[1] 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: 
(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 you to plot a straight line course to the destination.
Eight-symbol addresses were introduced in "The Fifth Race", opening up new plot lines by connecting Stargates to different galaxies. The additional symbol acts as a type of "area code".[15] 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 a regular wormhole. This has been generated in a variety of ways in different episodes, although the main way is using a Zero Point Module (ZPM).[16][17][15][18]
The show has never featured a nine-symbol address, so the purpose of the ninth chevron is unknown (fan theories include other galaxy clusters, time travel, alternate timelines, and completely alternate universes). However Robert C. Cooper has stated that the purpose of the ninth chevron will be revealed in the upcoming series, Stargate Universe.[19] The extra chevrons are so rarely used that Stargates are often seen with those two chevrons embedded within the stone platforms that hold many of the gate upright (see the image at the top of this article). This has often led to the misconception that a Stargate only has seven chevrons.
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 the planet. It has been confirmed that the missing glyph on numerous DHDs differs based on how each stargate is positioned on different planets. The glyph that is hidden under the pedestal of the stargate, unseen along with the two chevrons, cannot be dialed by the 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.[20]
The show makes it clear that every Stargate originally had its own DHD, located directly in front of the gate and facing it.[12] 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 functioning DHD.[12]
The Wormhole
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 called the "kawoosh" (since Crusade),[21] resembling a surge of water or quicksilver. The "kawoosh" is portrayed as a symbol of the Stargate's power, invariably causing characters to be awed.[22] Any matter which comes into contact with the "kawoosh" effect is destroyed, as is dramatically demonstrated by a pair of smoking shoes in the episode "Prisoners".[23]
Power for the wormhole can be drawn from both the point of origin (the dialing Stargate's power source) and the destination.[24] One of the most basic and repeated axioms of Wormhole Physics, the (fictionalized) field of study pioneered by the character Samantha Carter, is that unless an extraordinary amount of energy is being generated at either end, a wormhole can only be maintained for 38 minutes at a time.
The actual portal of a Stargate appears inside the inner ring when an address is correctly dialed. This has the appearance of a vertical 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 through which once one had crossed, 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".[11] 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[25] (though during the episode "New Ground" 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[26] 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 gate's "kawoosh".
Passage through a Stargate is usually accompanied by a visual effect of shooting through a tunnel in space, though it is just meant to be a visual aid. The representation of the transit is sometimes almost instantaneous, and other times it appears to last up to 20 seconds. This is thought to be just a representation of how it might look. Since they are disintegrated, it would be impossible to truly see the inside of a wormhole or travel through it.
The actual time the travel takes on average 6 seconds. Novice travelers often emerge from the gate trembling as if they've been on a "roller coaster ride", and although it is often omitted later in the series, they also experience the sensation of being "frozen stiff."[11] The character Charles Kawalsky compares Stargate travel to pulling "out of a simulated bombing run in an F-16 at eight plus g" because of the energy going through the wormhole at such speed and then being "reintegrated".[11] In other episodes, however, gate travel is superficially no different to stepping through a doorway.[27] This has since been explained as problems with the man-made interface on the Earth gate, and has mostly been fixed over the years of Stargate operations.
The visual effect resembles a spinning wispy tube, and was in Season 9 (and the first season of Atlantis) revamped to resemble a misty tunnel lit by shooting rings of light (almost looking like other stargates in the network). The Atlantis wormhole is significantly greener in colour whilst the new-style Milky Way wormhole was blue. The film depicted the first moment Daniel Jackson entered the pool, walking through and remaining in apparently physical form as if the pool was in fact simply a covering for the black of the wormhole beyond.[1]
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.
- The maximum period of time a wormhole can be maintained under normal circumstances is slightly more than 38 minutes. This time limit can be circumvented in the presence of continuous high level power generation at at least one end, coupled with a continuous transfer of matter or energy through the wormhole.[28] A wormhole can also be maintained for longer than 38 minutes if time dilation effects cause time to run slower at either end.[29]
- An object entering a wormhole will retain its kinetic energy upon leaving the other end. In simple terms, anything leaving a wormhole does so at the same speed at which it entered. ("Upgrades")
- A barrier less than three μm from the event horizon will not allow matter to reintegrate through a wormhole.
- Matter can only pass one way through a wormhole; matter attempting to enter an incoming wormhole will cease to exist.
- Certain forms of radiation, including radio waves, can pass through a wormhole in either direction. Visible light does not seem to pass through in either direction.
- 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).
- In "Ripple Effect", Carter claimed the average travel time was 0.3 seconds, contradicting the pilot "Children of the Gods" and other episodes, where it takes roughly six seconds. One possible explanation for this discrepancy is that the 0.3 seconds may be the literal interstellar travel time, with the other 5.6 seconds involving the disintegration-reintegration process.
- A large surge of energy delivered to an outgoing wormhole can cause the wormhole to jump from the receiving Stargate to the next nearest one in line. ("Solitudes").
- A DHD can be used to create an event horizon in a Stargate even it is "buried". ("48 Hours").
- 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, if exterior forces redirect the wormhole to the same gate, it will connect to the gate in another time period. ("1969" and "2010").
- The unstable vortex ("kawoosh") created when a wormhole engages will vaporize any matter with which it comes into contact.
- If a sufficiently dense material blocks the event horizon of a Stargate, it will prevent the event horizon from forming. This will prevent either incoming or outgoing wormholes from being established("48 Hours"). See below (gate obstruction)
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
When an object passes through the event horizon (the "puddle"), it is not immediately transferred to the destination Stargate, but rather the portion that has passed through is dematerialized and held in a "hyperspatial buffer".[30] An object that hasn't completely passed through the event horizon may be pulled out again,[30] and its atoms will rematerialise from the buffer as it is extracted. The gate does not begin transmitting an object until it has entirely passed through the event horizon. This ensures that only complete objects are transferred. Objects in the buffer remain in a state of suspension. This has been used to "store" people in medical need,[30] but this is a dangerous maneuver, since any disintegrated matter in the buffer "ceases to exist" if the wormhole shuts down before the signal is transmitted.[31] Furthermore, each time the gate is activated the buffer is wiped clean to receive new information.[32]
Several facets of the Stargate are necessary for it to function as a useful personnel transporter. Matter emerging from a Stargate retains any kinetic energy it had while entering, so a person running into one Stargate will hit the ground running upon emerging from another. (Weapon projectiles also maintain their trajectory upon transit- a bullet fired through a Stargate is just as dangerous as it would be otherwise) Also, the transmitting Stargate does not allow the air molecules of the local atmosphere to pass through. The show explains that the Stargate differentiates between objects attempting to pass through the event horizon and things that would naturally exert pressure, such as water, air, lava, etc.[28]
Gate obstruction
A wormhole is prevented from forming if a significant obstruction is present inside the Stargate's ring. Consequently, it is fairly common for Stargates to be semi- or permanently sealed by burying them, invalidating that Stargate address.
Another means of controlling travel through a Stargate is by placing a barrier a minuscule distance (less than three μm, in the case of the Earth's Iris) from the event horizon,[31] which allows the wormhole to form but prevents the reconstitution of matter upon arrival through the gate. In other words, a connection can be made but any matter trying to exit the gate will not regain its original structure, and hence will be annihilated. The Iris on the Earth Stargate and the Shield on the Atlantis Stargate perform this function, and have been seen to be used as an effective defensive precaution, whilst still allowing radio communication through the open wormhole.
Iris-type barriers also suppress the "kawoosh" by not allowing the matter to form. Such barriers, however, are not the only way to prevent the "kawoosh". Several aliens, including the Asgard and the Nox have demonstrated the ability to open a wormhole without the "kawoosh" (Both races were allies of the Ancients, and may possess better knowledge of the Stargate than other races).
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 lock each chevron.[23] Power can be fed directly into the Naqahdah that comprises the gate; power harnessed from lightning strikes has been shown to be sufficient.[12] 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.[24] 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.
Secondary gates
Some planets are known to possess "secondary" or "backup" Stargates.[33] The second Stargate is normally inactive, with the primary Stargate (defined by the presence of a functioning Dial-Home Device) receiving all incoming wormholes.[28] 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"). 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.[33]
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.[34] 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.[28]
In Redemption, the second stargate was destroyed by Anubis. In order to continue their stargate program, the US Air Force "borrowed" 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 bought from the Russians for the Korolev.[4]
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.[34]
The Stargates themselves are extremely resistant to damage or destruction: in one case, a Stargate survived a direct hit from a meteor,[25] whilst another was still capable of creating a stable wormhole while on a planet near a newly-formed black hole.[29] A Stargate has also been seen to continue functioning whilst entering a sun,[35] 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 Stargate.
Exceptions
Under normal circumstances, a wormhole can only be maintained for slightly more than 38 minutes.[30] However, on a few occasions, this limit has been surpassed. The first breach of this general rule occurred to Earth's gate connected to a planet in the proximity of a black hole.[29] This method was also used intentionally by the Ori.[36] The second incident occurred when energy-rich liquid beings maintained the power for a gate while a Russian vehicle had its transmitter stuck.[28] The third exception happened when Anubis used a weapon made by the Ancients (or with their technology) to slowly feed energy to a Stargate. The gate remained active and eventually exploded.[4] Finally the fourth exception happened after Earth ordered an attack on the Asuran home planet, after it was discovered that they were building warships. The Asurans responded by sending a satellite containing a Stargate to Lantea, which activated and a powerful beam came through hitting Atlantis' shield. The expedition had hoped that the Stargate would shut down after 38 minutes, but, as Dr McKay stated, the Asurans had an unlimited number of zero point modules, with that amount of energy at their disposal they could hold the Stargate open indefinitely.[37]
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.
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 what is presumably a weapon of an Asgard ship; what the device actually is is unknown but it is known to be Asgard.
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 "Exodus", 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 lbs in weight.[4]
Milky Way
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 addresses.
8-symbol addresses will yield:
- (38×37×36×35×34×33×32) = 63,606,090,240 possible addresses.
If a 9-symbol address operates like 8-symbol addresses it will yield:
- (38×37×36×35×34×33×32×31) = 1,971,788,797,440 possible 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.[11] 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,[1] 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.[11] (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
Depicted in the original film, the Stargate found at Giza, Egypt was the first discovered by humans of Earth, in 1928. In SG-1 the same gate is used by the SGC for the first three seasons to explore other planets.[38] It was discovered in the season seven finale, Lost City, that the glyphs have syllable pronunciations that allow a gate address to be spoken aloud as a destination name. This is how the planet Proclarush Taonas was named. The gate symbols are as follows:
| Position | Glyph | Constellation | Position | Glyph | Constellation | Position | Glyph | Constellation |
|---|---|---|---|---|---|---|---|---|
| 1 |  |
Origin symbol†(earth) | 14 |  |
Microscopium | 27 |  |
Taurus |
| 2 |  |
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 |  |
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 |  |
|
| 13 |  |
Aquila | 26 |  |
Cetus | 39 |  |
Leo |
†This symbol is unique to the Stargate recovered from Giza. In the movie, Dr. Jackson interpreted it as representing the Sun over the peak of a pyramid. Other Stargates are described as having their own unique origin symbols as well.
Pegasus galaxy
In the spinoff series Stargate Atlantis,
an expedition dials the 8-symbol 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, but used gates of a slightly different design. As these gates were built at a later date than the original Milky
Way network, they may be of more advanced design, however at this point the differences appear mostly cosmetic.
The alternative Stargate design in the Pegasus galaxy is one of many things the producers of the shows employed to differentiate the sister shows SG-1 and Atlantis. Pegasus Stargates are designed with blue chevron lights instead of red ones, and the address symbols are groups of small blue lights (rather than embossed figures) that light up sequentially instead of rotating. In SG-1 it is stated that the rotating section of the gate unlocks when sufficient power to dial has been fed to the gate, allowing manual dialing in case the DHD is damaged or not present, as on Earth. In "Phantoms", an off world DHD is destroyed, and Dr. McKay states that there is no way to manually dial the gate. Presumably this is because the Pegasus gates lack the free-rotating central ring.
Unlike the Milky Way gates, Pegasus gates are depicted with 36 symbols. 7 symbols are still required to dial an interplanetary address, adhering to the same constraints as a Milky Way gate. With 36 symbols, the Stargate Network in the Pegasus Galaxy has:
- 35×34×33×32×31×30 = 1,168,675,200 possible addresses.
8-symbol addresses will yield:
- 35×34×33×32×31×30×29 = 33,891,580,800 possible addresses.
If a 9-symbol address operates like 8-symbol addresses it will yield:
- 35×34×33×32×31×30×29×28 = 948,964,262,400 possible addresses.
Thus there are fewer possible addresses in the Pegasus Galaxy, although it may still be the case that there are more Stargates there if more of the possible addresses are utilized than in the Milky Way.
In a departure from the definitive "anywhere to anywhere" ethos of SG-1, the only Stargate in the Pegasus galaxy capable of reaching Stargates in the Milky Way is the one located at Atlantis.[39] This is due to a special "control crystal" unique to the Atlantis DHD, without which a Pegasus Stargate cannot encode its eighth chevron.[39] Unlike any other known gates, the Atlantis Gate can also identify the point of origin of the gate that tries to dial in, and can block an incoming wormhole.[39]
Some Pegasus Stargates are orbital: they lead to open space, something never seen in the Milky Way. This is again a departure from the "personal travel" rather than "starship travel" ethos of SG-1, as these gates are used solely for space-faring vessels and never for humans. It is possible that the Ancients created these gates for localized travel to worlds where ground-based gate travel would be hazardous, either due to climate or atmospheric difficulties or due to native creatures. Orbital gates are depicted without a DHD, being powered by three power nodes spaced equally along the outer ring (see image). In the show, Puddle Jumper vessels and Wraith Darts have built-in DHDs to explain how a craft would return through an orbital gate.
Orbital Stargates have sometimes been referred to as "Spacegates" by characters on the show, but this has not been stated to be an official term.
In "Irresistible",[40] a plan was put in place to create a bridge of linked Stargates in the void between the Milky Way and Pegasus galaxies to circumvent the need for a ZPM to effect travel between Atlantis and Earth (see McKay-Carter Intergalactic Gate Bridge below).
One concept directly ported from SG-1 to Atlantis, and that was the idea of an "Iris" that allows wormholes to form but stops anything trying to emerge.[18] The Atlantis Stargate has a force field that serves the same function. As with SG-1, only the protagonists' gate has this capability, being the singular real defense they have against major attacks (thus allowing the shows to continue despite having insuperable enemies).
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 was seen during a shot of McKay's laptop in the episode "Sateda" but most of their names are currently unknown.
