This defines the “The The [[Magic_System]]” so the CLI doesn’t make it look too “sparkly.”
The Hum: The background radiation of the universe. In the UK, it is “tamed” by the Ley-lines. It smells like ozone and static electricity.
The Friction: The physical price of casting. If you force a spell through a cheap focus (like a Ninth Knot wand), the air around you gets “hot” and “heavy.”
Aetheric Sludge: The byproduct of over-industrialized magic. It gathers in sewers and damp corners of the Tannery. It looks like iridescent oil and can cause “Logic-Bleed” (where you forget how to use a doorknob for ten minutes).