When Merlin's Ancient treasure materialized in the Glastonbury cavern, SG-1 discovered among the riches a piece of Ancient technology resembling a keyboard with three levels of keys inscribed with Ancient symbols. It had been brought back to the SGC where Dr. Lee attempted for six months to activate it without success, and it was about to be sent to Area 51 for further study. Carter succeeded in interfacing her laptop with the device and noticed that the electromagnetic output continually fluctuated between high and low frequencies. However, when she tried to stabilize it, the device emitted a brilliant flash of light causing Carter and Mitchell to be shifted out of phase. Initializing the device had caused only a localized effect to Carter and Mitchell without affecting other inanimate objects in the lab.

The device does not give off any typical energy signatures emitted by Ancient transporter technology. It does, however, emit traces of lepton radiation, which indicates a similarity to the technology of the crystal skull of P7X-377, although Daniel's previous experience with the crystal skull did not allow him to see or interact with Carter or Mitchell while they were out of phase. The technology is also similar to the cloaking device of the Sodan. An individual who is out of phase would be able to see, hear, and communicate with another shielded by the Sodan cloak, however the two devices do not share the same phase and the two individuals would physically pass through each other. The device demolecularizes matter and transports it into another dimension, but an individual who has shifted out of phase maintains a link to the device through subspace so that he remains out of phase, as controlled by the device, even if he leaves the immediate area or travels offworld.

According to M-theory, which unites the five superstring theories, there are 11 spatial dimensions that exist in parallel with our own physical reality, and Carter concluded that she and Mitchell had been phase-shifted to an alternate dimension by the device. Carter and Mitchell appeared to be invisible to those in the SGC, but the invisibility effect was not reciprocal. They were able to see, hear, and experience everything happening around them in the SGC but were only able to physically interact with each other and with the device itself. Although the device was designed to be interactive from both dimensions, it projected a holographic interface display of Ancient writing which changed pages when it was touched, but which was only visible in the alternate phase as a security safeguard.

Using texts recovered from Glastonbury, Daniel's research turned up several oblique references to Arthurian legend, including the word "Anawyn," which could have been a variation on "Annwn," the Celtic Underworld where King Arthur journeyed in search of 13 sacred objects, one of which was a cloak said to render the wearer invisible. The cloak, called "The Mantle of Arthur," had been kept at Bardsey Island by Myrddin (Merlin). Daniel theorized that The Mantle of Arthur was not a cloak, but rather referred to the device, which medieval historians would not have understood and would have attributed to Arthur, their king, although it is much more likely that the device had been the work of Merlin.

When Dr. Lee isolated the algorithm that Carter had used to synchronize the energy emissions coming from the device, he counteracted Carter's algorithm from his own computer to allow the emissions to return to their normal frequencies, expecting it to reverse the process, but instead the device activated again and Daniel was sent out of phase. From the alternate dimension, Daniel was able to read and translate the information from the device's holographic display. He had only begun the translation, however, when Dr. Lee attempted again to reverse the effect and accidentally drained a significant portion of the device's power supply. With only 15 minutes before critical failure that could strand Daniel, Carter, and Mitchell, Daniel used the master screen and a key combination to reverse the device. In a flash of light, all three returned to their normal phase, including Mitchell who had traveled offworld but who had remained linked to the device through a subspace connection.

Although Daniel had only begun to retrieve information from the device before it permanently ran out of power, he was able to determine that it contained a log that described its true purpose. Merlin had been developing an invention so important that he had relinquished his ascension and had retaken human form to complete it. He believed that the Ori represented a significant threat to the Ancients and to this galaxy, but knowing that the Ancients would prevent him from taking action, he went to great lengths to hide his research. His phase-shift device had been created for the sole purpose of keeping his research secret from the Others as he completed his invention - a weapon capable of destroying ascended beings. The log indicated that he had completed the weapon on Earth, but had then relocated it to another planet. The given gate address, 20-2-35-8-26-15, eventually led SG-1 to Camelot on PX1-767.

Following the initial incident with Merlin's device, Carter made additional modifications hoping to take advantage of its potential to hide military targets. Because its original power source, a small crystal inserted in a compartment in the back of the device, was depleted, Carter substituted three naquadah generators and used her laptop to control the technology. The modified device affected not just animate objects within close range but instead could shift all matter within a preset range into an alternate dimension. In order to bring everything back completely, however, the device must maintain a connection with every single molecule that it sends out of phase, which requires a tremendous amount of energy, and Carter implemented a failsafe that would automatically bring everything back into its original dimension in the event of a power disruption.

At the insistence of the IOA, Carter's modification of Merlin's device was tested on P9C-882, where an entire village was taken out of phase to hide it from the Prior. The initial attempt succeeded, but a slight power fluctuation triggered the failsafe and caused the displacement field to collapse. Carter was attempting to rig an Ancient capacitor between the device and the generators to feed the power more evenly when she was shot by an Ori warrior who damaged two of the naquadah generators. The remaining generator was only powerful enough to take a single room out of phase, but when the power crystal from an Ori staff weapon was later connected, the displacement field expanded to include the whole village, allowing it to be taken out of phase long enough to prevent its destruction by the Ori warship.

Carter continued to experiment and to rewrite safety protocols on the device so that increasingly larger fields could be transported to another dimension. When a laboratory mishap drew her into an alternate universe, Carter was able to use her research to take the entire planet out of phase and to save an alternate Earth from an Ori attack. Her plan required 700 gigawatts of power, roughly 80% of the power generating capacity of the United States, which was drawn directly from the US power grid in the alternate universe. Similarly, when the Odyssey was pursued and attacked by Ori warships, Carter had hoped to mimic Merlin's phase-shift technology to take the Odyssey out of phase and prevent the ship's destruction. However, without Merlin's device, the plan could not be implemented quickly enough, and the ship was spared using time dilation and time reversal instead.

Cross Reference: Alternate Dimension, Alternate Reality - Universal Bridge, Camelot, Crystal Skull, Glastonbury, Holographic Projection, Invisibility, Bill Lee, Merlin, Merlin's Treasure, Merlin's Weapon, Naquadah Generator, P9C-882, PX1-767, Sodan Cloak

Episode Reference: Arthur's Mantle, Line in the Sand, The Road Not Taken