There are many worlds in the infinite cosmos. To call them worlds, however, is a shortcoming. They are all distinct pockets of separate reality. They are governed by different laws, contain different types of existence, and they all float in the expanse.

The expanse is, as one might aptly guess, a limitless expanse of void. To perceive it in its raw form is to invite madness. All those that see a semblance of it, much like marks of possibility, see it differently; though the nature of it remains more or less consistent.

The expanse, technically, contains no matter and simultaneously all matter. The spaces between each reality are empty, and yet the expanse contains those empty spaces and the pockets of tangible reality as well.

One cannot simply traverse the expanse, as attempting to enter the empty space of the expanse would create a new small pocket of reality and prevent you from entering it properly. It can, however, be viewed.

Each pocket of reality is more or less tangible in the expanse, and two or more pockets can collide. When this happens, they either drift apart again or stick together. When the latter happens, one pocket is hypothetically capable of absorbing the other.