The Roil

CONCEPT
The Universe is finite. It is cosmically vast, to be sure, but it does have an edge, an endpoint beyond which reality as we know it ceases to exist. Beyond that edge is the Roil, a truly infinite expanse of raw, energetic potential. What we think of as the Big Bang is actually more like a Tiny Hollowing within the Roil; our unfathomably huge Universe is merely a microscopic bubble formed within the Roil.
 
Bubbles like these exist everywhere within Roil, an effervescence of creation, where fragments of that cosmic potential briefly solidify into a set form of reality before crumbling back into non-existence. In the Roil, these Reality Bubbles last for a comparative instant; within them, eons upon eons pass for as the Universe within forms, evolves, and eventually dies.
 
The Roil exists in countless dimensions. While it is technically possible to travel to it via reaching the edge of the universe, this is impractical for numerous reasons. However, any one can reach the Roil from any physical point within a Universe via dimensional travel. Indeed, with the proper protections, it is possible to use the Roil as a medium by which to access other Universes entirely, as well as different points within a single Universe.
 
This is the secret of hyperspace travel, time travel, pocket dimensions, alternate timelines, and other such deviations from the standard reality.
 
The Roil is also the secret behind the reality breaking powers of superhumans, magic, and breaker technology. The Roil being a realm of pure potential, it is capable of rewriting existence as we know it. By channeling the energies of the Roil, one can perform impossible feats. Civilizations that manage to achieve reliable access to the Roil have the capacity to effect God-like change in the Universe.