Stargate (device)

This article is about the device in the fictional Stargate universe. For other uses of the term, see Stargate (disambiguation).

In the Stargate science fiction universe, Stargates (called the Annulus on K'tau, and the Chaapa'ai [tʃɑpɑˈaɪ] by the Jaffa and Goa'uld) are large ring-shaped devices created by the Ancients and scattered on Earth-like planets throughout the Milky Way and other galaxies as well. Stargates can be used to open wormholes from one gate to another, allowing nearly instantaneous travel between them. Matter can only pass one-way through the wormhole, from the gate that dialed ("initiated") the connection to the gate that was dialed, but radio signals can travel both ways.

The Milky Way's Stargates

Stargates are 22 feet (6.7 m) in diameter and made of the heavy mineral naquadah. They are usually found standing vertically, though they still function normally in other orientations. There are two types of Stargates known, the type located in the Milky Way galaxy and those placed in the Pegasus galaxy. A Milky Way Stargate has an inner rotating ring with thirty-nine inscribed symbols and an outer stationary ring around which are nine triangular structures called "chevrons" that are the digit places of coordinates to other planets. For a six chevron dial, plus the point of origin, this gives a total of 1,987,690,320 possible combinations from one Milky Way Stargate, though many of these combinations are invalid within the constraints described below. When coordinates are dialed, the inner symbol-bearing ring rotates until the dialed symbol is adjacent to the chevron, registering that symbol as a dialed coordinate by "locking" the chevron. In the Stargate SG-1 series, a locked chevron glows red. This rotation and locking is repeated until all coordinate symbols are dialed. The gates are usually found accompanied by a dialing device called a DHD, or Dial-Home Device, that powers and activates the Stargate, opening it to the dialed coordinates. Because the gate on Earth was found without a DHD, the Stargate team on the Earth developed the technology to interface with the gate in order to power it and dial it by the use of computers. When dialing the Stargate using a DHD, its inner ring does not spin, it simply just activates each chevron, as they are entered on the DHD. Some species in the series possesses the ability to instantanously activate a wormhole, thus being able to dial the gate without actually using a dialing device.

The Pegasus galaxy's Stargates have inner rings that do not physically rotate. These gates are digital in design, as well as the DHDs within that galaxy. However, the gates only have 36 symbols, totaling 1,168,675,200 possible combinations from each Pegasus galaxy Stargate, fewer than those in the Milky Way.

In normal operation, seven chevrons are activated to link to gates within the Milky Way galaxy. Six non-repeating symbols establish the coordinates of the destination and the seventh is always set to a symbol representing the Stargate's current location. This gives 1,987,690,320 possible coordinates in our galaxy, but not all represent valid gate coordiates. In the original movie only one valid set of destination coordinates was known, those of the planet Abydos, and it was thought that only those two Stargates existed. At the beginning of the Stargate SG-1 series, however, a large set of additional valid coordinates were discovered engraved in ruins on Abydos. According to what is known on this series, the symbols represent constellations of stars, with the destination point being triangulated between them. Most sets of destination coordinates do not have a Stargate located at them and dialing them will fail to establish a wormhole; there are sufficiently few valid coordinate sets that randomly dialing the Stargate is largely futile.

It was later discovered that more distant Stargate "networks" could be accessed by dialing eight chevrons, with the extra chevron serving as a sort of "area code" and the Stargate requiring significantly more energy to reach the destination. The Asgard world Othala in the galaxy of Ida and also Atlantis in the Pegasus galaxy was reached in this manner. This was not done routinely, however, as Stargate Command lacked both a sufficient power source and any other valid long-distance coordinates. The function of the ninth chevron has not been determined.

When a Stargate's wormhole is initially established the watery "event horizon" bursts outward in a destructive wave resembling a surge of water or quicksilver, dubbed the "kawoosh" by SGC personnel. In the original movie the opening of the Stargate was accompanied by earth tremors, but this issue is resolved in the SG-1 series with the development of more sophisticated control systems. Several aliens have demonstrated the ability to open a wormhole without the "kawoosh". The wormhole is prevented from forming if there's an obstruction inside the Stargate's ring, and consequently it is fairly common for Stargates to be semi-permanently sealed by burying them. Another means of controlling travel through a Stargate is placing a barrier a minuscule distance (less than two micrometres) from the event horizon, preventing the reconstitution of matter upon arrival through the gate. The iris on the Earth Stargate performs this function and is an effective defense while still allowing radio communication through the open wormhole.

Stargates have some built-in safety functions as well. The gate does not begin dematerializing and transmitting an object until it has entirely passed through the event horizon - though if a Stargate is shut down while an object is partway through, the portion that is through the boundary vanishes. The gate does not allow air molecules to pass through the gate; also on several occasions a wormhole has been opened between a Stargate on Earth's surface and a Stargate under the surface of an alien world's ocean and the water was prevented from flowing freely through it.

Normally, a wormhole can only be maintained for about thirty-eight minutes at a time. The Stargate that established the outgoing wormhole determines how long the wormhole is held open, and can generally close the wormhole at will. One exception to this rule occurred in an episode of Stargate SG-1 when an outgoing wormhole was established to a Stargate that was in the process of falling into a black hole; due to the gravitational time dilation the remote Stargate was experiencing the wormhole could not be shut down. The connection was eventually severed by forcing the wormhole to jump to a different destination Stargate as described below. The wormhole also can only transmit matter in one direction, but EM waves (radio, gamma, etc.) can be broadcast in the other direction as well.

At least some planets possess "secondary" or "backup" Stargates. The second Stargate is normally inactive, with the other Stargate receiving all incoming wormholes. If the originating Stargate receives a power surge while the wormhole is open, however, the wormhole can be made to "jump" to a different gate than the one originally dialed. Normally the wormhole jumps to the closest gate in the network, in the case of a planet with two gates this is the other, normally inactive gate, on that planet. On one occasion a Stargate was hit by an energy weapon as Stargate SG-1 team members returned to Earth through it, causing them to be transmitted to a second, previously unknown, gate on Earth that was located in the ice of Antarctica. The DHD is apparently responsible for determining whether a Stargate is set to receive incoming wormholes or not; the Russians were able to use their DHD to override the American Stargate's (Stargate Command) reception of incoming wormholes to retrieve their own returning Stargate exploration teams.

In addition to the Ancients, the Tollan have demonstrated the ability to build Stargates with the assistance of the Nox after SG-1 introduced the two races in the first episode to depict the Tollan. Also, in the season 5 episode Ascension one Ancient using materials and tools readily available on Earth to average citizens was able to build a small one-shot Stargate that could only dial one address. ("Sorry, but you're going to have a pretty big credit card bill this month. Oh, and you're going to need a new toaster.")

The Giza Stargate's symbols

^*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 have their own unique origin symbols.

Pegasus Stargates

In the spinoff series Stargate Atlantis, an expedition dials the 8-symbol address Missing image
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from Stargate Command to travel to the Ancient Lost City of Atlantis, 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. Pegasus Stargates have blue chevron lights instead of red and the address symbols are groups of small white lights instead of raised figures. Unlike the Milky Way gates, there are 36 Symbols on the gate, but 7 symbols are still required to dial an interplanetary address. The address ring does not rotate; instead, the symbols light up sequentially to indicate which one is currently selected. This probably means that manual dialing of Pegasus gates is not possible. The visual effects used for the "traveller's-eye view" is also different, with the traveller hurtling down a twisty green tube of mist.

In an apparent departure from the standard "anywhere to anywhere" dialing capabilities of Stargates, the only Stargate in the Pegasus galaxy that's capable of reaching Stargates in the Milky Way is the one located in Atlantis. This is due to a special control crystal apparently unique to the Atlantis DHD without which a Pegasus Stargate cannot encode its eighth chevron. This is likely a deliberate feature, as the Ancients fled the Pegasus galaxy to take refuge in the Milky Way and sealed their fortified city behind them. Pegasus Stargates are the same size as Milky Way Stargates and can be kept open for the same maximum duration (38 minutes), so they likely operate on the same principles with only cosmetic differences.

Some Pegasus Gates are orbital: they lead to open space, something never seen in the Milky Way. These apparently have no DHD, and are used almost exclusively for space craft travel, specifically that of the Puddle jumper and the enemy Wraith Darts. Orbital Stargates are powered by three power nodes spaced equally along the outer ring. These nodes take the place of the standard DHD in powering the Stargate. The Puddle Jumpers have inbuilt DHDs making travel back through these gates possible, and it appears that Wraith Darts have a similar capability, as they were able to open a wormhole remotely during their first encounter with the Atlantis team.

The Atlantis Stargate also features a protective force field similar to the Iris installed on Earth's Stargate by the SGC, to prevent enemy travellers rematerializing. This technology appears to be unique to Atlantis so far.

Prior use of Stargate concept

The concept of the Stargate did not originate with the movie. Several science fiction authors, notably Andre Norton and C. J. Cherryh had previously used the concept of devices creating portals spanning interstellar distances. Norton's Witch World was colonized by humans and other races using such portals. In Cherryh's Morgaine series, the Gates' potential for facilitating time travel makes them a danger to causality and therefore to the future of civilization. The title character is engaged on a centuries-long quest that takes her from world to world via the gates, setting each gate to self-destruct just after she has used it to move on to the next.

See also

• List of known Stargatesfr:Porte des étoiles

es:Stargate (aparato) it:Stargate (dispositivo)