The Slipstream is a zone of force created by the Galactic Ley Line. As forces in the Metaverse interact with the Otherverse, space is folded, creating small Pocket Worlds and dimensional anomalies. Within the region of the slipstream, which is often several parsecs wide centering on the main zone of force, it becomes possible for a starship using a special Transluminal Drive to slide partially out of this universe, and enter into its own pocket continuum which can exceed the universal constant of C. Many races use the Slipstream as a method of travelling quickly from world to world, and so come to depend on the Galactic Ley Lines for commerce, diplomacy, warfare, and exploration. While the forces which create the Galactic Ley Line can not be generated or manipulated, but it can be used much like currents in the ocean, speeding travel while reducing the energy cost of transluminal velocities.
Slipstream technology can be mastered by nearly any culture capable of post-atomic industrial technology, and requires little more energy output than a simple atomic reactor. Travelling along the slipstream is more of an art than science, however, and skilled pilots often develop an intuitive feel for the flow. The Slipstream twists and distorts as the many universes interact with each other, and while it is possible for any relatively decent astrometric computer to calculate the path of a ley line, fine details of the slipstream require a second by second oversight and decision making capability that few computers are capable of.
A slipstream provides a “path of least resistance”, altering the fundamental laws of the universe in a way that contradicts general relativity, but the amount by which the laws of physics change depend on a number of variables. Slipstream channels are described as being “Deep” or “Shallow”, defining how much transluminal velocity it is possible to achieve, and “Broad” or “Narrow”, defining how much leeway is given for piloting. Galactic leylines have multiple channels covering several parsecs of space, which twist together like individual cords braided into a strand. Leylines also have a direction of flow. It is invariably easier to travel in the direction of the flow than against it, and moving against the current requires the pilot to engage in maneuvers not unlike a sailship tacking against the wind. While the flow of a leyline is generally spiralling clockwise inward toward the core of the galaxy, retrograde currents which “backflow” are not uncommon.