Long-range communication device

"There were these stones, and if you place them in one of several recesses around the outside of the device, it activates it, and allows you to connect with someone far, far away—across the galaxy, inter-galactically even..."

- Rodney McKay

The long-range communication device is a two-way communication device which creates a psychological and physiological link between the users on each end, swapping their minds into each other's bodies. It was originally created by the Alterans millions of years ago, before they left their home galaxy. A variant of the original was developed by the Tau'ri sometime around 2009.

Overview
The long-range communication device is used in conjunction with the long-range communication stones. When the stones are attached to the device, they create a link with the nearest active communication stone, allowing the user to take control of the person to whom the stone is linked and vice versa. As long as the link is active, the user controls the recipient's body as if it were their own.

The device, thus far, has no known limit to its range; it can function seamlessly over billions of light years. However, it appears to be unable to establish a two-way link over intergalactic distances without the aid of a second communication device on the other end. For example, when Daniel Jackson and Vala Mal Doran used one to connect to the Ori galaxy, the couple they connected to were not switched in return until a second device was briefly engaged; when it was disabled, the connection back to Earth was severed. Conversely, a communication device activated by Neeva Casol in the Pegasus galaxy was to create a two-way link between her and Jennifer Keller, despite Keller not having used a communication device in return, and likewise Everett Young was able to swap with a blueberry alien with the use of a single device.

Once a link is formed between two individuals, it cannot be severed until the stones are removed or power to one or both devices is cut off. The Alteran version of this device will maintain a one-way connection without a companion device, while the Tau'ri version will disable the connection on both ends if either side loses power.

The device establishes a physiological link as well as a mental one, linking the well-being of those using the device. Extreme sensations such as suffocation or burning will be shared, and if one body dies the other will die with it; if the body that died is revived after death, the other is too. Its shown that when one person on the link is killed, the other is as well, shown with the deaths of Ginn and Amanda Perry. However, the minds of the people killed can become trapped in the stones and under certain circumstances connect with someone using the stones and temporarily take over their bodies. The device does not share every sensation. For instance, if a person were to become intoxicated while the device is active, they would only be affecting the host body of their partner; if the device were to be deactivated or disrupted while that person is intoxicated, the user would find him/herself sober in the original body, leaving the other user to feel the effects of intoxication. This is also true of injuries such as broken bones, as when Ronald Greer broke his leg during the Lucian Alliance attack on earth, the person he had swapped with was unaware of the injury.

Daniel Jackson believed that the device was able to translate from Ancient to English based on his first experience with it, though later events show that the Ori followers whom they communicated with speak English. When Everett Young used the device and swapped with a blueberry alien, he could not comprehend their language, which uses clicks and screeches, nor could he communicate in his own tongue.

Original Alteran device
The original Alteran long-range communication device has a hemisphere-shaped base about two feet in diameter with a crystalline spire coming from the center. There are eighteen communication stone slots spaced equally around the base. When active, the spire turns blue. While the specifics of the device is unknown, what is known is that the device draws power from subspace. Once activated, the device is impossible to shut off; it has no "off switch" and any stones attached to it are locked in place. The only known method the Tau'ri have for disabling the link is to destroy the device. A Prior has been shown to be able to deactivate the device without the need for violence using his powers.

History
The first encounter the Tau'ri had with a device was through the communication stones found by Jack O'Neill and Joe Spencer. Their possession of the two stones created a weak psychic link between them, which activated in proximity of the stones. Later on, the communication device was discovered in Avalon. Realizing that the stones interfaced with the device, Daniel Jackson and Vala Mal Doran used it in hopes of meeting non-ascended Ancients living in another galaxy. Instead, they linked to Harrid and Sallis, heretics who had discovered a similar device outside Ver Eger. The device found in Avalon was destroyed when Cameron Mitchell and Teal'c threw it into the unstable vortex of an activating Stargate. The device in Ver Eger was taken to Celestis to be destroyed, but Seevis' contacts in Celestis smuggled it out to Ver Isca before that could happen. Vala, while stranded in the Ori home galaxy, used it to link to Daniel and warn Earth of the impending Ori invasion; however, the device was rendered useless when Tomin shot it with his staff weapon.

In 2008, the Atlantis expedition had an encounter with one of these devices. Neeva Casol activated one while stealing artifacts from a village, switching with Jennifer Keller, who was the last person to touch the related communication stone in Janus' lab. To restore them both to their proper bodies, Ronon Dex shot the device, disabling it.

Ori long-range communication
Though the Ori have not been shown to build a physical version of the long-range communication device, a Prior has shown to be able to duplicate the effect using their powers (likely in conjunction with their staff). A prior in the Milky Way demonstrated this with Gerak, bringing both himself and Gerak to Celestis, whereupon Gerak was converted to a Prior himself. It's not shown if their bodies were being controlled by someone else during the exchange.

Tau'ri device
The Tau'ri, despite not understanding the technology completely, have managed to construct their own version of the device. This variant is much smaller and box-shaped. The top of the device has a flat panel with five intersecting rings, where the stones can be placed. When a communication stone is placed in one of the five rings, the panel lights up and the link is established. There is also another, smaller varient that holds only a single stone.

The Tau'ri version of the device has the advantage of being easy to shut off, in contrast to the original which must be disabled or destroyed (if only due to their lack of understanding in how it operates). It comes with a removable power cell, allowing the user to break the connection at will. Alternatively, since the stones are placed on a flat panel and not attached in any way, they can simply by picked up to break the link. The person doing so tends to use gloves or other cover for their hands while doing so, presumably to keep the stone from imprinting on them.

Unlike the original, outside factors have been shown to disrupt the link to various degrees. Destiny's Faster-Than-Light engine creates a subspace disruption when engaged or disengaged, breaking the link for a few seconds. The blueberry alien mind probe will sever the link if used on one of the two users, preceded by a bout of severe pain in the subject. Intense weapons fire directed at Destiny's shields from several blueberry alien motherships has also severed the link. When a blueberry alien that had handled a stone was killed moments before an attempted connection, Everett Young, who had connected to the alien twice before, was unable to connect to anyone, including Earth. The connection to Earth was eventually restored. Other factors can affect the stones, such as Stargate travel over intergalactic distances. High levels of radiation on one end of the connection can also effect it, preventing it from being severed when the stones are removed or even when the base is turned off, but this can be bypassed so the connection can be broken.

Another effect of the device not shown with the Alteran version is the transfer of traces of memory from the host body, which can be experienced in the form of brief visions or dreams. This is likely a side effect of the host being exposed to Goa'uld brainwashing technology, as it does not occur under normal circumstances. This version has also been shown to be able to connect to a completely alien species, namely the blueberry aliens, provided they have an active stone.

The device is also able to clear the imprints on stones, rendering them inert until they are imprinted by another person. If the imprint is not cleared, the stone will remain active despite not being place on the panel. The blueberry aliens used their stone a second time to exploit this, connecting with Vanessa James. This presumably worked because Destiny's communication device was active at the time.

History
The Tau'ri had developed the variant of the communication device by 2009. At least one device was stationed at Icarus in anticipation of traveling through the Stargate to the nine-chevron address. When the base came under attack by an unknown force, an evacuation was immediately underway. However, rather than dial Earth, Dr. Nicholas Rush dialed the ninth-chevron address, effectively stranding roughly 80 Icarus personnel aboard the Ancient ship, Destiny. As the last person to evacuate the base, Col. Everett Young spent valuable seconds in securing a device. As a result, he was critically injured as the base exploded and he was flung through the Stargate and across the Gate room aboard Destiny. In the ensuing chaos, Rush discovered the device and discreetly made use of it. Afterwards, the device was used by the expedition to keep contact with Earth and make visits to families, as well as occasionally call in experts when Destiny's crew's own experience is insufficient. On one occasion, the device was used to bring a family member to Destiny. Maryann Wallace was brought abord in order to help her see her son Eli again and convince her not to give up on her fight against HIV. However, this was a one-time occasion that was only performed thanks to the influence of Camile Wray, but is an action that all of the crew wish they perform, so that their family members could see what they are doing.

During Colonel Young's attempt to make a report to Earth, he switched bodies with a blueberry alien aboard a mothership who had come into possession of a communication stone. After an attack by the aliens, Young used this to sneak aboard the mothership to try to rescue Chloe Armstrong, who had been kidnapped by them. He ended up freeing Nicolas Rush instead, and when Young used a mind probe given to him by Rush, the connection was severed. Rush killed the alien whose body he'd been inhabiting before Young could return. The blueberry aliens later used the stone in their possession to infiltrate Destiny and sabotage its FTL drive, allowing them to mount an attack which Destiny could not flee from. Fortunately, Jeremy Franklin managed to use the Destiny interface chair to bypass the damage and get Destiny to safety.

After switching with David Telford on a scheduled switch, Nicholas Rush had a dream made up of residual memory carried over from Telford. In this, he learnt that Telford was the spy for the Lucian Alliance. In order to prove this and to allow Colonel Young to interrogate Telford, Rush switched with Telford again during a scheduled transfer and posed as him on Earth. Tailed by Doctor Daniel Jackson, Rush made contact with the Alliance through a cell phone found in a safe-deposit box. However, this aroused the Alliance's suspicion as he did not use the code-word to identify himself, which revealed to the Alliance that someone else was inhabiting Telford's body. Rush was then captured and taken away on a cargo ship. He was then forced to reveal his real identity, and work on dialing the ninth chevron for the Lucian Alliance. On Destiny Young interrogated Telford about his actions. Young then used the stones several times to report to Earth. After Telford proved to be completely uncooperative - and to even lied to him - Young had Corporal Marsden switch bodies with General Jack O'Neill so that O'Neill could help in the interrogation. Even with O'Neill there, Telford refused to cooperate, so O'Neill was sent back. Young then vented the atmosphere in Telford's room, killing him. He then revived him. Doing so also effected Rush on the other end of the link, but he too was revived when Telford was. Telford's brainwashing was broken and he revealed all that he knew about what was going, on including the location of the planet Rush was on. This led to an attack by the George Hammond, which forced the Lucian Alliance to evacuate to Destiny. The travel through the Stargate to Destiny severed the connection between the Telford and Rush. Telford however remained free of the brainwashing, even in his own body. The Alliance later used the stones to bring in a team of doctors from Earth to treat the injured, by forcing Wray and three others to switch bodies with them. The doctors succesfully saved TJ and Telford, but were unable to save Kiva or TJ's baby. Telford and Camile Wray later used the device to report back to Earth on the aftermath of the invasion, where they were ordered to keep a small number of the invasion force onboard Destiny. Later, one of the Alliance members, Ginn, switched with Amanda Perry in order to report what she knew about a Lucian Alliance attack on Earth to Homeworld Command. They were both were killed when Simeon killed Perry in Ginn's body.

When Senator Michaels decided to examine Destiny to see if building a new Icarus Base was feasable, she brought with her Doctor Andrew Covel, the two switching with Camile Wray and Ronald Greer. On Destiny, the two took a tour of the ship and Michaels chatted with Chloe Armstrong while Covel examined the signal Rush found and the two determined that building another Icarus Base was not viable as they didn't believe the crew would survive long enough. On Earth, the Lucian Alliance attacked by crashing a Tel'tak into Homeworld Command. The ship was armed with a 50 to 70 megaton naquadria bomb. Wray and Greer attempted to reach it, rescuing along the way what turned out to be the Alliance pilot. In the process they accidentaly exposed Michaels' and Covel's bodies to a fatal dose of radiation in the process. The two learned of this when an FTL drop-out severed the connection for a few moments. The connection was unable to be severed due to the radiation and Covel's desperate sabatoge, but it was temporarily severed again by an FTL jump so Varro could tell Wray and Greer how to disarm the bomb. The two failed, but Rush fixed the problem with the stones and sent Michaels and Covel back with the nessacary information to complete the task. Due to problems with the Earth device, a connection was unable to be made for over six days. However, once the problem was fixed, David Telford connected to inform the crew that the disarming was succesful.

When trying to connect with Earth, during the six days that the stones were down, Chloe Armstrong fell asleep while connected to the stones, allowing the conciousnesses of Ginn and Amanda Perry, which had continued to exist in the communications stones as the connection was not properly severed, to take control over her body. Due to a glitch, Ginn experienced incidents where she seemed to relive her death by strangulation and grew weaker and weaker as time went on, allowing Chloe and Perry, who was weaker than both Ginn and Chloe to surface more and more often. Eventually the Destiny interface chair was used to transfer the two minds into Destiny's mainframe.

As part of their plan to dial Destiny from Langara, Richard Woolsey brought two communications devices of the smaller varient to Langara where he tricked a Langaran captain and Administrator Halpren into picking up the stones, allowing Scott and Young to switch with them and pose as them so they could take over the facility while on Destiny, Vanessa James gave the two a tour of the ship to try to garner sympathy from them. The ruse was eventually exposed when a Langaran soldier overheard a conversation revealing the truth and the plan failed.