Alternate reality drive

The Alternate reality drive was a drive that was developed by Rodney McKay in a parallel universe.

Overview
"Think of it like a tap pouring water into a bucket. When the bucket is full, the drive engages." — Rodney McKay

The drive was designed to transport matter through the Inter-universal bridge to access parallel universes. It is powered by Subspace capacitors, which provides near Zero Point Module levels of power. The device has to be encased in a protective area of the ship, as it gives off radiation that could be lethal for prolonged exposure. Despite its function of transporting ships to parallel universes, the ship would remain in the exact same position (for example, in geo-stationary orbit above M35-117) after every jump. The drive had a different, yet similar function for that of the Quantum Mirror. If C-4 was to be used to destroy the machine, it would more than likely tear a hole in the fabric of space/time, which would be big enough to destroy a solar system.

24th Century
The technology was encountered when an alternate Daedalus appeared over M35-117 when its drive forced it to the normal universe in 2384. Sheppard's team became trapped on the alternate universe's Daedalus when the drive malfunctioned because of it's flawed design. The team became lost while jumping through alternate universes. McKay was able to modify the drive to reverse and go back to all the universes they previously visited. They were able to get home and abandon the ship before it jumped again. McKay theorized that the ship only had about half a dozen more jumps before the drive burned out. The normal universe's McKay stated that he would be able to build his own version of the drive easily without any of the encountered flaws, but Sheppard advised him not to.

25th Century
By the 25th Century Rodney McKay was able to to build his own version of the drive easily without any of the encountered flaws.