Named after Saunt Hemn, Hemn Space is a description of a given system in as many dimensions as required to reason about it under a specific question. An object moving through conventional three-dimensional space can for example be described in a 12-dimensional Hemn Space, with 3 coordinates each to describe the position, rotation and movement of either. Theors set up Hemn Spaces so that calculations will be as simple and clear as possible, using Orbital elements instead of Saunt Lesper's Coordinates for example, when reasoning about Satellites.
Hemn Space is the theorical Basis for the discussion on Narratives in the Polycosm, essentially a set of coordinates in the Hemn Space describing the Polycosm which are internally consistent, e.g. the momentum of a particle at a given point leads to another coordinate in the same Hemn Space, an instant "later" that represents the state of the universe internally consistent with said momentum.