Link

The Link worked on planet P3X-289 as a guard against the toxic environment on the planet. Survivors from the planet acces what they call the Link for getting all the information they need and have so survived for 400 years, because of this dome's energy barrier that's also controlled by the Link. What the people didn't know was that the Link altered their minds so that they wouldn't know that their numberws for 300 years had decreased from over 100 000 people to this days 1 000. ([SG1: "Revisions")