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 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 through the wormhole from the gate that made the connection to the gate it is connected to, but radio signals and other electronic data can be sent back through it.

Stargates are 22 feet in diameter and made of the heavy mineral naquadah. They are usually found standing vertically, though they still function normally in other orientations. A Stargate has an inner rotating ring (with at least one exception being the Pegasus galaxy's stargates, where the inner ring does not physically rotate) 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. This gives a total of 208,728,361,158,759 (39⁹ or ~208 trillion) possible combinations, though many of these combinations are invalid within the constraints described below. When coordinates are dialed, the inner symbol-bearing ring rotates until the the dialed symbol is adjacent to the chevron, registering that symbol as a dialled 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 dialled. 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.

Spoiler warning: Plot or ending details follow.

In normal operation, seven chevrons are activated to link to gates within the Milky Way galaxy. Six establish the coordinates of the destination and the seventh is always set to a symbol representing the Stargate's current location. This gives 3,518,743,761 possible 'local' destinations (39⁶), assuming that all combinations represent potentially valid addresses (which may not be the case, depending on the details of how symbols are translated into a destination location). 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 dialling them will fail to establish a wormhole; there are sufficiently few valid coordinate sets that randomly dialling the Stargate is largely futile.

It was later discovered that more distant Stargate "networks" could be accessed by dialling 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 miniscule distance 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 the destination's backup Stargate instead. 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 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. Also, one Ancient was able to build a one-shot Stargate using materials and tools readily available on Earth. ("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.")

Pegasus Stargates

In the spinoff series Stargate Atlantis, an expedition dials an 8-symbol address to travel to the Ancient 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. The address ring does not rotate; instead, the symbols light up sequentially to indicate which one is currently selected. This may mean that manual dialling 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" dialling 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.