Bulk

For a more scientific viewpoint, see brane cosmology on Wikipedia.

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In Solar Storms, the bulk represents the hyperspacial space-time that the component universes of the Multiverse rest in. Here, multiple universes float within an even deeper void than that of space itself, called the aether, which, at least for the purposes of those universes it holds, acts as a 'preferred frame'. No normal matter can exist within the aether, instead, in order to function, an object moving through it pretty much has to become its own miniature universe. Regalia are all capable of doing this, but less advanced ships must usually rely on the network that they have constructed, often termed hyperspace. Access to a black hole and sufficiently advanced technology can enable forging new hyperspace paths, although this is a dangerous endeavor.

Because factors like distance, mass, and velocity are largely a function of the nature of matter within a universe, this allows for extremely rapid transit between two points inside the Multiverse, though for extreme distances, 'rapid' is still relative, as the aether itself has a top speed, and follows its own form of relativity in much the same way the Universe has a top speed.

The term 'superbulk' sometimes refers to the interactions of individual multiverses within this scheme, but is actually technically a part of the same bulk. It can be visualized by imagining that each individual universe is a thread of seemingly infinite length, bundled and twined together with trillions of others, forming a rope - a 'multiverse'. This rope frays and splits in many areas, binding it to other such ropes, forming the great cosmic web of the Megaverse - the Dark Rein, in the standard case. It is thus possible to imagine that a single universe can be close to, or even a member of, several multiverses, though this does not seem to be the case for the Milky Way's host 'verse.

Even with the immense amount of data gleaned from the renlai and primii over hundreds of cycles, the interaction between reins is not fully understood. A few even claim that the rules of logic and math are not 'universal', just as physical laws do not appear to be.