The Dimension cannon or the Dimension jump was a device that could travel to different dimensions by ripping a hole in the universe and hopping through the Void, at the cost of breaking the walls of the universe. It was created in Pete's World by Torchwood. (DW: Doomsday)
History
First Version (Battle of Canary Wharf)
After the Cybus Cybermen left Pete's World to travel to the Doctor's universe, Torchwood created a device that could hop to another universe. This first version resembled a yellow disc, this device would hang by someone's neck like a necklace and could teleport at the same position on the chosen world where they teleported from the other world. The use of the dimension cannon opened the breach further and further and raised the temperature on Pete's World. After the Tenth Doctor sucked the Cybermen and the Daleks in the Void, the breach closed itself because of the amount of Void stuff present. (DW: Doomsday)
Second Version (War in the Medusa Cascade)
In Pete's World, Rose, Mickey Smith and Jackie Tyler used a new dimension cannon that once again broke the walls of the universe to enter our universe.
This new version unlike the original, was handheld and could travel to different parts of the space, but needed to recharge for 30 minutes after each use. The dimension cannon could also measure time lines.
Mickey and Jackie also used it to help save Sarah-Jane Smith from a pair of Daleks following their invasion of Earth.
The device did not function at all until the events of the 2009 Dalek Invasion of Earth , when the walls of reality started to break down following the use of Davros' reality bomb. Following the invasion and Davros being prevented from using the reality bomb in the Doctor's universe the walls of the universe eventually started closing themselves, a process that the DoctorDonna called a dimensional retroclosure, this closure suggests that the cannon would once again not function. (DW: The Stolen Earth / Journey's End)