Reality itself can be thought of as our particular flow of energy in our own temporal continuity. That is, our reality can be defined as our path through time and all the energy (and thus matter) which flows along times arrow from the past into the future. This continuity contains all of the conventional energy and matter native to our timeline. In line with the Laws of Thermodynamics and Laws of Conservation of Energy and Matter, our continuity (i.e. our timeline).
The Multiverse
There are infinite realities encapsulating every potential divergence, choice, or outcome of any given event. Each potential outcome occurs within its own continuity or timeline. Each timeline continuity can be thought of as its own reality where a unique set of circumstances (composed of choices and event outcomes) which set it apart from neighboring realities. Within the multiverse realities are "grouped" by similarity, those realities "closest" to our own have the most similar outcomes. By closest of grouping, it is not literal, but rather their Divergence Factor (the relative magnitude of differences between realities) can be conceptually thought of as being "closer" to a given reality.
In scientific terms, each reality is connected by a variety of factors to each other reality. Most notably connected via layers of subspace, the depth into subspace from one reality to another grows proportionally to the Divergence Factor from one reality to another. The higher the Divergence Factor the more energy / power is required to breech the subspace barrier from one reality to another. These subspace barriers are breeched naturally when anomalies in two separate realities align and cause a Splice or what in antiquity was called an Umbral Passage. Other names for this kind of anomaly exist, but there are areas of instability which can connect two otherwise distant realities momentarily and allow passage.
The Cuil - Warping Reality
A measure of alterations to the current reality within its own continuum, though not a measure of Divergence Factor. At Cuil 0, reality is normal and unchanged. The Cuil measures warping or alteration of the prime material plane in layers of abstraction. In a very real sense, the Cuil Factor measures how far the natural laws of a given reality diverge from the normal for that reality. This is not to be confused with a measure of Oswalds or other measures of Aether, though they are related. Aether itself can alter the nature of reality and thus can be used to cause warping an alteration which would register on the Cuil scale. As the Cuil Factor increases the very physical laws which govern existence change with it, which can cause wondrous and disastrous effects.
Conventional drive systems which rely on the warping of space-time also could be measured with a Cuil Factor. Scientifically the application of subspace fields to a given area of space-time alter the physical laws which govern that region. A warp field can be used to change the gravitational constant of a given region or cause even more exotic effects. These are not _true_ reality manipulations but accomplish similar effects. A true manipulation alters the physical laws by drawing energy from Cuil Realms deeper within our own continuity's subspace domain.
Beryllium Bronze is a unique alloy which can channel, focus, and manipulate Cuil Energy which in turn manipulates reality.