Zygma beam

Zygma beams were a type of power source created by zygma energy for the time cabinet and other devices for time travel. Magnus Greel helped develop the idea while he was the Minister of Justice in the 51st century. It behaved like an elastic and was stretched to its fullest between the 51st century and the 1800s when the time cabinet was initially used. (TV: The Talons of Weng-Chiang) A zygma beam that came into contact with the Doctor's TARDIS began to carve up its dimensions, causing several small time loops and expulsion of Nyssa and Turlough to the beam's destination. (AUDIO: The Butcher of Brisbane)

The zygma beam's arrival in the 1800s released chronon radiation which followed Earth's telluric currents in the magnetosphere to create the Dragon Paths. The Fourth Doctor compared it to a paddle ball, the paddle being the 51st century, the ball being the time cabinet and the string being the beam. (PROSE: The Shadow of Weng-Chiang) The effect of the zygma beam snapping was equated with dropping a few nuclear warheads in a thousand different times at once. (PROSE: Emotional Chemistry)