Notes on the subject of Aether,
the Fifth Element, and itsProperties
The legendary Fifth Element that sits as arbiter at the center of the cardinal forces, the spark that begot all of existence, the primordial chaos that exists before and beyond space and time, the essence of the arcane, the breath of God in Heaven... There are no shortage of names for the concept of the fundamental energy. To wield it freely and fully is to undermine reality itself, and it is the true goal of the Alchemist.
Put simply Aether is mass and energy liberated of form, a pure kind of existence that has had no limits imprinted upon it. It fills the void between material planes, also known as the Atherium, in limitless quantities, acting as both the glue that keeps realities together and the fuel for the expansion of space and time within them. Mana, the building block of magic that is known by so many other names, is the reduced form of Aether that seeps into reality through the cracks and pools in places of power, a pale imitation of the real thing.
In its natural state Aether simply cannot exist in the material plane, when exposed to a lower reality it quickly dissipates into the world around it, either as Mana or as a violent transmission of newly born force and mass. Which of the two possibilities becomes manifest is largely dependent on the nature of its release.
Stable Aether that doesn't simply unmake itself, violently or otherwise, is possible in only extremely controlled circumstances where magics are at play to contain it. In such circumstances it makes excellent fuel for all methods arcane, accelerating the casting time, efficiency, and power of spells wrought from it exponentially- for those incredible magi that are capable of dealing with its volatile and unwieldy nature. The Doctor's own body is one such controlled containment field, and this is the primary source of his great prowess as a mage.
By contrast, when unleashed without any stabilizing force it can be disastrous, as it violently un-creates all in its path, or arguably worse creates violently. As the fundamental particle that both matter and energy are derived from contact with Aether that is not finely controlled leads to a volatile mixture of both. The usual result is simply a swift death, but those who live through exposure are greeted with a fate far worse. Those unfortunate souls are twisted into terrible amalgamations of living and un-living tissue and driven beyond the brink of madness by pain felt across multiple timelines- including the ones where the exposure simply killed them.