The stargate is an advanced piece of technological hardware developed by an alien culture, linking planets together across the vastness of space and providing instantaneous travel. The Earth stargate was first discovered in 1928 in Giza by Professor Paul Langford, noted archeologist. For the next several decades scientists worked to unlock its secrets, finally succeeding in 1994 when they established a wormhole to another world. Afterwards the stargate was decommissioned and the project shut down, until 1997 when the first Goa’uld incursion emerged from the gate. The SGC was established to deal with a new, credible threat. A second stargate with a dial home device (DHD) was later discovered in Antarctica that same year. This second gate was supposedly placed in storage and sent to Area 51 for safe-keeping but in actuality dissident forces within the government used it to conduct covert operations. Eventually, it was shut down for good.

The original gate was thought destroyed in late 1999 following a disaster in orbit (the gate endured unprotected reentry into Earth’s atmosphere). In reality the Russian government found and salvaged the gate, and used it to begin their own stargate program in 2000. Meanwhile the SGC then removed the Antarctic stargate from storage for use as their primary gate.

The next year the SGC borrowed the Russian’s DHD in order to save the life of a trapped SG team member. A backlash destroyed the DHD, leaving the Earth with no functional DHDs.

In 2002 the forces of Anubis mounted an attack against Earth and its stargate. In order to save the planet the gate was sent into space and exploded some 3 million miles from Earth. After tense negotiations, the Russians agreed to returned their stargate – the original gate discovered in Giza in 1928 – to the SGC to continue the program.

To this day no one fully knows who created the stargates or the stargate network (see below). Originally, the SGC believed that the Goa’uld were responsible but it soon became apparent that the Goa’uld had little more than a basic understanding of the gates’ function. Subsequent evidence now suggests that the stargates were in fact created by a race known as the Ancients – possible descendants of humans. One of the four great races that seeded the galaxy with life, the Ancients created the gate network to allow instant travel across the stars without clumsy spacecraft or long flights. A stargate allows a traveler to reach any intended destination in a matter of moments by merely walking through its wormhole.

The gates themselves are created from refined naquadah ore, similar to quartz. Naquadah is a stable mineral with a half-life of 150 years, capable of many applications and uses, including weapons of mass destruction and the generation of clean energy. In its refined state the naquadah of a stargate only reacts with neutrinos – an electrically neutral particle – converting and storing the energy as a large superconductor. Neutrinos are not affected by the electromagnetic forces which act on electrons and are thus able to pass through great distances and matter without being affected. This energy is stored in a crystalline lattice structure within the stargate.

The stargate itself is a perfectly circular device, some 10 meters in diameter comprised to two sets of rings and nine “chevrons” placed equidistant along the outer circumference. The second ring – the inner ring – is placed inside the larger outer ring, and moves independent of its greater “housing.” The chevrons are used to denote and “lock” onto a symbol or glyph on the inner ring’s surface. These glyphs are used in a particular order to denote a specific gate address and to “dial” the stargate (see “Glyphs” and “Dialing” later in this section).

Each stargate weighs 64,000 pounds, and each is identical in appearance with the exception of one glyph on the inner circle, representing that stargate’s point-of-origin. Most stargates are also found in the presence of a “Dial Home Device,” or DHD. Also comprised of naquadah and control crystals, the DHD is the “brains” that make a stargate function. It gives commands to the stargate and completes the dialing procedure. Without a working DHD a stargate must be manually manipulated and dialed. A DHD also contains a small naquadah power source that sends a charge through the stargate powerful enough to generate a wormhole.

As alluded to earlier, a stargate is dialed by using a sequence of glyphs coded into a correct sequence to yield a valid gate address. All gate addresses (save a handful of notable exceptions) utilize six glyphs and a unique point-of-origin. The final step requires the activation of the master crystal in the center of the DHD to send the charge that forms the wormhole. If a gate address is valid, the stargate generates a stable wormhole between the two points. Otherwise, an error results and no wormhole is formed.

A stargate cannot dial an address that is already in use (i.e. one that has a functional wormhole currently activated). Such a world simply fails to dial, in essence receiving a “busy signal.” Furthermore, a gate currently engaged cannot begin a dialing sequence. Thus one can dial a stargate and intentionally keep it open in order to prevent the other side from dialing out to any other address. The Goa’uld commonly employ this tactic when planning an attack on a planet with a stargate, preventing anyone from escaping.

In some rare cases a DHD may be non-functional, destroyed, or not even present. In such instances a stargate can still be dialed and activated, although doing so is very dangerous. First, a charge must be delivered into the stargate, powering the energy crystals inside. The easiest method involves using an electrical current, either from a man-made or natural source such as lightning. However, if a stargate’s energy-absorption capacity is exceeded the naquadah could become saturated and explode in a tremendous blast – 2,000-3,000 megatons – enough to wipe out all life on a planet. After the gate has been charged the address can be manually dialed by hand, engaging each of the seven chevrons in order.

The Earth stargate – save for a handful of specific instances – has not been in operation at the SGC with a functional DHD. Instead a complex computer program acts as the “dialing computer,” inputting and receiving commands to the stargate. This stopgap measure contains its own risks, as the Earth’s dialing computer can never be as accurate or responsive as a DHD. As such, the dialing computer takes longer to dial a wormhole and of the possible 400 feedback impulses that the stargate provides, the SGC is only able to recognize about half. This allows the stargate to be used when the gate’s own built-in safety protocols would normally not allow travel. During a time when two stargates were in operation on Earth, the presence of a DHD allowed one gate to “trump” the other, preventing its use.

The Earth dialing computer took over 15 years to develop and even then its discovery was fortuitous luck. From the inception of Project Giza through 1997, the Earth stargate could only dial one planet – Abydos. The dialing computer could not account for stellar drift over the course of several thousand years, and Abydos only worked because it was the planet closest to Earth. As such it was only a matter of time until the Earth stargate would be unable to dial any other world. Furthermore, the device was so primitive that initial gate travel was something of a hap-hazardous “bumpy ride;” there were strong temperature variances as matter was reintegrated as well as strong disorientation for travelers.

Eventually both of these problems were corrected and while the Earth’s dialing computer still is no substitute for a functional DHD, it now accounts for stellar drift and provides a much more pleasant traveling experience.