Break out of the frame | Updated June 2, 2005 | Get the frame back



General info

Eighth chevron

To use an eighth chevron (which seems to be a galaxy code), a stargate needs 10 times as much power as it does normally (SG-1: The Fifth Race)

A DHD needs to have an extra control crystal to be able to lock an eighth chevron. (Home)

In the Pegasus galaxy, only the Atlantis control system had the extra crystal, possibly as a security measure to keep the Ancients' old homeworld (Earth) safe. (Home)

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Safety protocols

The stargate system has safety protocols and protections built into it, to prevent connections that will do dangerous things, like dumping unstable isotopes into a primary. (SG-1: Red Sky)

Another safety protocol is designed to keep energy signatures from mixing together one way the gate does this is to erase the energy buffer (the memory of energy signatures stored in its crystals) every time a new wormhole engages. (SG-1: 48 Hours)

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Pegasus galaxy specifics

Some of the stargates in the Pegasus galaxy are located in orbit around planets, reachable only by spaceship. (Rising pt 2, others)

The Atlantis gate is the only one that can dial back to Earth. (Rising pt 1)

It's the only one whose DHD had the additional control crystal that allows the eighth chevron to lock, allowing inter-galactic travel. (Home)

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Dial Home Device (Ancient term unknown).

The standard device connected to a stargate, covered in two concentric circles of symbols, with a central crystal. Pushing the right symbols in the right sequence, then the central crystal, activates the stargate.

Without a DHD, travel is impossible unless a substitute is found (like the SGC's dialing computer), or unless the gate is hooked up to an external power source and the inside track is moved manually.

A DHD needs to have an extra control crystal to be able to lock an eighth chevron. (Home)

In the Pegasus galaxy, only the Atlantis control system had the extra crystal, possibly as a security measure to keep the Ancients' old homeworld (Earth) safe. (Home)

top | DHD


Physical structure


Made of naquadah, which has a decay rate (half life) of 150 years (used for dating) (SG-1: A Hundred Days).

Weight: 64,000 pounds in the Milky Way galaxy. (SG-1: Redemption, part 2) Unknown if the weight changed in the Pegasus galaxy.

The stargate consists of two rings.

The outer ring is stable, and holds nine chevrons (ordinarily, only seven are visible above the surface of whatever the stargate is being held upright in, but all nine exist). These chevrons light up one by one as the gate is dialled, as each is assigned a particular symbol from the inner ring. The final (top) chevron is for the point of origin, to complete the address.

The inner ring is covered in 36 symbols, and the ring itself moves, so that symbols can be aligned with chevrons as need be.

The gate element is a superconductor that absorbs energy in many forms. (SG-1: Torment of Tantalus)

It converts and stores energy in reservoirs, making it possible to unlock and spin the mechanism manually when enough power is stored. (SG-1: Torment of Tantalus)

Stargates can draw power directly from a source at the far end of the wormhole, making it impossible to disconnect the gate from the point of origin (SG-1: A Matter of Time, SG-1: Watergate).

Drawing power from the other end of the wormhole seems to negate the 38-minute window.

If a stargate's energy-absorption capacity is exceeded, the naquadah the gate is made of could become charged and explode, in a tremendous blast: 2,000-3,000 megatons, with environmental effects that could wipe out all life on a planet. (SG-1: Redemption, part 1)

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Pegasus galaxy gates

The stargates in the Pegasus galaxy are a bit different than those in the Milky Way -- clearly a newer model. (Rising pt 1, multiple other eps)

The gate itself has a different hue -- more purply rather than solid grey -- and the chevrons are teal rather than orange. (Rising pt 1, multiple other eps)

The inner ring is stable and blank, rather than movable and covered in symbols. When a symbol is chose on the DHD or other dialing device, that symbol appears as a lighted shape on the inner ring, and the light itself circles around until it hits the appropriate chevron. The chevron lights up, locking the symbol into place for the duration. (Rising pt 1, multiple other eps)

This allows for much faster dialing than is possible with the older model. (Rising pt 1, multiple other eps)

Pegasus galaxy stargates have 36 symbols. (The Brotherhood)

top | Physical structure



Wormhole basics

To keep a wormhole open, you have to send something through, even if it's just a radio wave. (SG-1: Redemption, part 1)

Ordinarily, a wormhole will close within a short period if nothing enters it. (SG-1: Redemption, part 1)

The wormhole won't send anything through that isn't complete -- it holds the initial bits in dematerialized form, waiting for the entire unit (whatever it may be) to enter before rematerializing the entire thing at the other end. (Thirty-Eight Minutes)

This is actually implied all the way through SG1, but SGA is the first time it's explicitly stated. But this is why people can stick an arm (or whatever) into an outgoing wormhole and pull it back out again safely, rather than having the arm get cut off as it materializes on the other side.

If the gate shuts down while an object has only partially passed the event horizon, the object is sliced apart and the part inside the wormhole vanishes.

A wormhole can be maintained for 38 minutes. (SG-1: There But for the Grace of God, SG-1: Serpent's Song)

If the stargate is being powered by an alternate source, a wormhole can remain open longer (SG-1: A Matter of Time, SG-1: Watergate)

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Wormhole physics:

First-season (SG-1: Solitudes) theoretical explanation of the stargate wormhole: The gate is a giant superconductor that creates an artificial wormhole that transfers an energized matter stream in one direction along an extra-dimensional conduit.

A power overload can cause a malfunction, redirecting the energy to a second stargate on the same world.

This happened in Solitudes, when enemy fire against the stgargate on another planet caused the wormhole to jump to Earth's heretofore unknown second gate.

A stargate cannot activate when buried, but it can engage under water. (SG-1: Watergate)

The wormhole only allows matter to travel one way, but radio signals can be transmitted both ways. (SG-1: Watergate)

The gate has the ability to use density, molecular structure, and the force being exerted on the event horizon to determine whether something is trying to pass through. (SG-1: Watergate)

The alpha gate supersedes the beta gate as long as the DHD is connected. If it is connected only when in use, it will prevent crossover to the beta gate. (SG-1: Watergate)

The stargate on the receiving end of a wormhole temporarily stores the energy signature of each object passing through the wormhole before reforming the object, to be sure that it has all the necessary information. Reintegration of the object clears the signature, as does a new wormhole engaging (incoming or outgoing). (SG-1: 48 Hours)

Cutting off power to an outgoing wormhole prematurely can trap objects within the stargate system as energy, if the stargate on the receiving end doesn't have enough time to recreate the object. (SG-1: 48 Hours)

The signature is stored not in the energy itself, but is imprinted on the crystals in the receiving stargate, to be held in " memory" until the object is reformed. (SG-1: 48 Hours)

If an object is trapped, it is lost completely the next time a wormhole engages, clearing/erasing the " buffer" . The only way to reintegrate it is to remove the DHD's master control crystal before attaching the DHD. (SG-1: 48 Hours)

Removal of the master control crystal could result in massive uncontrolled energy flows -- and if stray current goes into the wrong conduit, the entire stargate could explode. (SG-1: 48 Hours)

The minimum amount of time needed to confirm a lock (fully establish a connection) is 3.5 microseconds. (Home)

nb: McKay said this within the hallucination he was having of a trip home to Earth, but there's no particular reason to believe it's not true.

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Most addresses consist of six points and a point of origin, but it's possible to use seven points and a point of origin (SG-1: The Fifth Race). There's room on the stargate for nine chevrons, but no more than eight have ever been used.

The unique symbol on a gate is its point of origin.

The Ancients designed the gate addresses to be pronouncable -- each symbol is a syllable in the Ancients's language, so that each address consisted of six (or seven) syllables plus the point of origin. (SG-1: Lost City, part 2)

Stargates can be used on a ship, but only if that ship is in orbit around a planet with a known address or point of origin, so the DHD can be properly dialed. A ship in transit can't use a stargate. (SG-1: Within the Serpent's Grasp)

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Dialing devices

The primary dialing device is the DHD. (multiple eps)

Can be dialed without a DHD or other dialing device -- all it needs is enough power hooked up to the ring, and to be moved manually. Two truck engines is sufficient. (SG-1: 1969)

A directed lightning strike will also work, although it risks overloading the gate mechanism. (SG-1: Torment of Tantalus)

The stargate can emit up to 400 feedback signals during the dialing process (tied in to the system's safety protocols?) (SG-1: 48 Hours)

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Stellar drift

DHDs compensate for stellar drift without the operator needing to worry about it. (SG-1: 2001)

Without a DHD or some other way to compensate for stellar drift, Sam believes that a gate can only be dialed to other gates within a 300-light-year radius. (SG-1: 2001)

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