The Observatory Spires
Located and anchoring the six axis points of the Hollow stand these immense Demiurge structures. Each Observatory consists of 3 Observatory Spires housing a single Observer at their core.
While the Reality Engine at the center of the Hollow stretches Chaos into a workable form, it is the Observers which transmute the world. The destruction of a single Spire, or rather its Observer, wouldn’t be existentially threatening to the Hollow as a whole, but would become detrimental to the surrounding Region.
Access to Central Observer Chambers is very restricted. This isn’t so much for the protection of the Observer itself, but rather for the intruder. Aether within Central Dogma is incredibly dense, and susceptible to unintended influence which could cause fatal feedback.
The thoughts on the Observers can be read most clearly from these chambers, but their language can barely be considered a language at all. It is more akin to a force.
Aether Pressure measures the relative stability of Reality within the Hollow. That being said, Stability is very relative; lesser density is just as dangerous as the greater. Pressure will drop relative to the distance from its source: the Observers.
More specifically, Aether Pressure dictates the level of influence the Observers have over Reality, and as their influence grows, so does the level of influence a conscious being has over the Aether.