Worldgate complexes

Worldgate complexes occur in two basic forms -- natural and artificial. The second type is often associated with or based on an incidence of the first.

Worldgates tend to occur naturally, over time, in places of unusually high population concentration. The minds of living beings have an effect on the structure of the physical universe around them; the constant pressure and desire of their minds for things they want and don't have tends to "fray" universal and sub-universal structure in the area. The more beings that are packed together in one space, the more tightly they are packed, and the longer the packing is sustained, the more likely that the local structure of spacetime will fray sufficiently to tear open -- either temporarily or permanently -- and allow access to other realities. Odd disappearances of objects, or (more usually) of people, is normally the first evidence that gating is starting to happen in a given area.

The population pressure required to spawn or maintain a worldgate is normally expressed by a combination of interacting variables known as the demobaric formula or gating pressure formula, the most important part of which is the threshold constant. Each planet has its own version of the formula and the constant: the relationship between them changes over time as the population of any given planet shifts. For example:

One of the earliest spontaneously-occurring worldgate complexes is at Chur in southeastern Switzerland. Chur grew extremely quickly after its founding in the early Bronze Age, positioned as it was at the crossing of two major trade routes associated with Alpine passes. It was, however, a very small city, so that the inflowing population were very tightly packed inside its walls. When the city's population reached a significant percentage of the Earth's population, it achieved the threshold constant