Noosphere

The Noosphere is, by the time of the ninth millennium, an ancient term coined as the new state of the biosphere. It was described as the planetary sphere of reason.
In its current usage it differs in the greater regards to the ancient usage, however it is still basically the same. The noosphere is the, very real, sphere around a planet which is formed by the collective reason of the race, or races, which live upon it, and is integral to said inhabitants' access to both the World of Souls and the Express. As such, it is essential for the usage of Magic. Such a clear advantage is likely the main reason why so many colonies tend to be on planets, as opposed to being orbiting stations. It is also believed that a noosphere blends a planet and its inhabitants together in ways to make them compatible, leaving introduced species at home and unperturbed by the different ecology. It is not an easy to observe phenomenon, and it does not take place unless a noosphere has developed around that planet. As for why noospheres appear around only some celestial bodies, particular planets, but not others and not on artificial habitats is unclear.
Noospheres, although having some sort of racial differentiation, behave in concert with one another regardless of racial formation. Such is how the Express is thought to have formed, or rather is formed after each cycle. Even after each cleansing of the galaxy, a shadow of a planet's noosphere remains, and so provide threads, however weak and diminished, for ships to be guided on. Although noospheres are a derivative phenomenon of sapient species, they can be effected to the point of near closure while their inhabitants still live, as well as other odd occurrences. The two most prominent examples of this are the Shattering, where the perforation of Earth's noosphere froze the Express within Human space, leading to drastically slower travel in that part of the galaxy, and the Breakdown, wherein the Blueprint of Man was used to change the noosphere of Johorne, thus cutting it off from Humanity at large with the solar system shrouded from the rest of the galaxy as a side effect.