Cosmology

The entire multiverse can be thought of as a great waterfall of aether cascading from the origin to the void. Everything that exists is formed from the vortices, turbulence, and eddies of this current. Any area within this multiverse but outside an individual universe is known as aetherspace. Individual universes are called conduits can contain multiple subconduits, dimensions, realms, planes, or whatever you want to call them. These dimensions can exhibit a number of different physical properties, as described here.

The Astral Dimension

Existing throughout the multiverse is the astral dimension. Journeys between universes are accomplished by traveling through the astral dimension.

The Mental Dimension

Lying "adjacent" (in a higher-dimensional sense) to the astral dimension is the mental dimension, a space of pure thought.

Conduits

The origin's energy crystallizes into boundaries that divert the time-stream's flow, forming individual universes, or conduits. The conduit walls separate the universe from the outside multiverse.

Aether

Outside of individual universes, aether flows from the origin to the void, forming the boundaries of conduits in its course. Aether is somewhat like a medium for time, and its flow is what gives rise to many properties of the multiverse. It's possible to travel to the Aether as a projected space known as the aetheric dimension.

The Origin and The Void

The origin and void aren't so much places someone can go as forces that control the form of the multiverse.

The Origin

The origin is a great infinite energy potential that produces aether. Travel to the origin isn't really possible: approaching essentially "burns up" whatever piece of reality draws near. That's if something can even get close enough to experience that effect. Approaching the origin takes exponentially more energy as the distance is closed.

The Void

The void is the complete opposite: energy is drawn out of anything that approaches, leaving it frozen and lifeless. Additionally, spacetime quantizes near the void, so layers of aberrant realms precede the void, dilating space and time to appear infinite unless bypassed. Even if someone could bypass these spacetime strata, the void exists in the far future, at the end of the multiverse. The structure of certain conduits allows black holes to form within them. These singularities pull in matter, and deposit it in the void, where entropy will act upon it until the multiverse ceases to be.

The Divine Realm

Above the time stream, in the mental dimension, deities exist within the divine realm. Lesser deities might only interact with a single conduit, but greater deities may have influence over several.

Superspatial Proximity

Superspatial proximity is when multiple things are in the same 3-dimensional location, but exist across different dimensions. Thinking of universes and dimensions like an office building, someone in superspatial proximity to you would be occupying one of the offices that differs in location only vertically, not laterally. Similarly, things can exist in superspatial proximity across dimensions if they are in the "same" 3-dimensional location.