The Void
From MYSTlore
The Void is the nearly empty space-like area that lies between Star Fissures.
[edit] Nature of The Void
Very few people have gotten the chance to study the void closely. Of those few, Gehn wrote this passage in his Lab Journal on Riven:
"I am discontinuing regular observations of the stars beneath the Fissure. Although I've been able to track the dark cloud-like formations that migrate through the starfield and have proven that their paths are cyclical, without proper instrumentation it is pointless to continue. My general theory concerning the nature of the Fissure has remained unaltered since it first appeared. It seems that the fabric of this Age has been breached in a way that permits matter to be hospitably exchanged between two discreet but overlapping spaces - much like a Link, but the apparent physical contradictions surrounding this juncture defy logical reason: the great column of wind that was formed when the Fissure first appeared suggests a vacuum as one might expect in space, yet my early experimentations revealed the presence of a breathable atmosphere. That Atrus and Catherine threw themselves into the void is further evidence that it might be safe to travel, but without knowing its true nature I cannot take the risk myself. It is also difficult to say what would happen if I were to reopen it after so long - but it is likely that the results would be catastrophic, given the changes that have occurred in this Age since that time."
From what Gehn has observed, and the experiences of the Stranger, it is apparent that the Void is filled with breathable air. It is also apparent that it is not part of an age itself. It has been proposed that the clouds of darkness are in fact entire ages in themselves. For example, the Stranger fell away from one of these clouds, which appeared to have the fissure connected, and fell directly towards another dark cloud. Therefore, it makes sense to assume that these clouds were in fact the ages Riven and Earth. Gehn could obviously observe more than one of these clouds, which points that the Void is the infinite area that contains all Ages. It can also be proposed that the white spots that have been mistaken as stars, are actually part's of the Void that are simply not obscured by the dark clouds.
[edit] Connections of Ages
It is unclear still, why certain ages, such as Riven and D'ni are connected with fissures. It is also unclear how the passage of objects (and people) between ages, takes place. In one age, such as Riven, there is an open Star Fissure, which objects can fall through, entering the void. But, as it is never directly shown in the games, it is unclear how objects enter the second age without a Star Fissure. From what is implied, and the position of objects after their travel, it seems that they fall from the second age's sky, as if the Void were that age's own space.