Psionics is a highly specialized field of advanced science which deals with those abilities of the mind which enable an Adept to affect the physical universe without physical manipulation of any kind, creating effects which appear to have no material cause. Psionics is thus referred to as a 'non-causitive' science.

In Space Opera, Psionics cannot affect the physical universe directly on a large scale, The amount of energy available to even the most psionically active mind is limited. Since the Law of Conservation of Energy applies, psionic talents would seem to be limited to such talents as telepathy, and clairvoyance, with highly restricted forms of telekenesis and teleportation perhaps available to the most powerful minds.

However, the ForeRunners had developed a very high level Science of Mind, and one of the outgrowths of that science was the PsychoKenetic Crystal. The PK Crystal or StarStone was discovered in the last days of the ForeRunner civilizations, immediately before the Final War which tore the vast interstellar empires apart and brought destruction to scores of thousands of planets. While the exact operation of the PK Crystal is not presently understood, it is believed to be able to tap the energy fields of a parallel, high-energy universe, perhaps those of tachyon HyperSpace itself. This means that enormous amounts of energy tan become available to the psionic Adept, and some rather spectacular applications of mental power tan be contemplated when a PK Crystal is employed to focus psionic talents and to boost their natural energy levels.