We define light with the Greek letter Lambda λ.
Light is the matter of a specific wave height in a room ϒ. Light is always present. Outer space, inner space on Earth, whatever.
The “color” of the light is specified later.
λ = (++#) Φ (+ #)
λ = (++#) Φ (β)
A pair of Fanny and Beta is named DELTA Δ.