Particle Reversal was a method of moving objects. The Third Doctor tried to use a particle reversal to see inside a Time Lord message pod, but the device he created failed and exploded. If he had succeeded it would have pulled the entire universe inside the pod. (TV: The Mutants) The Fourth Doctor used a modified technique to capture Lady Huntingdon. He used Iris Wildthyme's TARDIS' time rotor to program a particle reversal, pulling only Lady Huntingdon inside the message pod. (PROSE: Old Flames)