To move any appreciable distance within the Imperium, voyagers must resort to warp travel. This method of faster than light travel is rare, expensive and dangerous, as it requires the use of the unpredictable realm known as the warp, or immaterium. Vessels equipped with a functional warp drive are able to translate themselves into this other dimension of being by generating an envelope of Geller fields. These quixotic waves “bend” the ship through the veil of realspace into the immaterium. Once within this strange place, the ship is able to ride the currents and eddies that flow within the warp, frequently dropping back into realspace to check its positioning.
The immaterium is a bizarre and contradictory place, entirely unnatural to mankind. Looking upon the warp unprotected causes madness and corruption, and thus is greatly feared by almost everyone. Dimensions, colours, forces, and emotions operate entirely differently within the warp’s embrace, and this can drive even the most thick-headed crewman insane. Psykers of course, find such travel even more disturbing as their mystical senses are able to comprehend much more of the immaterium and the foul creatures that dwell within it.
Those that travel through the warp emerge to discover another of its disconcerting effects. Time does not operate normally within this other realm and so travelers can emerge to discover that centuries have passed since they started their journey, that they have merely been absent for a few seconds, or have even arrived before they left. Even skilled Navigators cannot predict how much time will be lost, gained or repeated over the course of a journey.
The warp is occasionally prone to great turbulence or storms of activity. These strike at random and last for an unpredictable amount of time. Whilst these storms rage, any vessels within are tossed about on roiling currents, sometimes being spat out at random locations. Other ships simply become trapped, unable to translate back into realspace, cursed to an eternity upon the waves of the warp. These storms disrupt communication across the Imperium and can sometimes herald a great disaster within realspace.