The Drift is the unknowable Otherspace accessed via the dimensional rifts created by the rift engines of starships. It is the principle means of faster-than-light travel (along with warp gates in the Aphelion universe.
The Drift cannot be comprehended by minds adapted to normal, stable space-time. Everything that is known about this has been related by the Navigators, or deduced from the experiences of travellers. It seems that the Drift is a distorted reality where the dimensions of space and time are replaced by probability, potential and association. Normal matter and energy cannot exist in this chaotic Otherspace and are apparently reduced quicly to raw “potentia”, the stuff of the Drift. There are powerful currents in the Drift, some of which link star systems and other concentrations of mass and energy. The “deepest” current in the Drift is believed to correspond to the passage of time, and it is difficult (some say impossible) to move against this flow.