The Onion · Essay 2 of 6
The Reflector
A source without a hinge is just noise leaving a hole. The core supplies expansion. The shell has to do something lawful with it, or the box either sprays or seals shut.
That lawful something is the reflector.
The Onion keeps a local state in three roles at once:
s₊ is expansion — the increment the core keeps injecting. s₀ is the mediator — a value that stays on and does not vote for push or pull. s₋ is contraction — the shaped counterpart of what has already been reflected. They are not three machines taped together. They are one object seen three ways.
Binary finishes too early. On or off is a closed sentence. A third value that can remain present without choosing a side is what lets the geometry stay open long enough to grow depth. Balanced ternary had that richness in hardware as early as the Setun computer: minus one, zero, plus one, with zero as a real state rather than an absence. The Onion borrows the logic, not the ferrite cores.
At the shell the reflector acts as
which means
Only expansion flips. The mediator is invariant. Contraction is not independently toggled; it is what expansion becomes after the flip has done its work and the inward fold has begun. Apply R twice and you are back where you started:
R is an involution. The process is still one-way. The core keeps feeding the component R inverts. There is no legal Onion step that un-generates λ. That is why time, in this geometry, is not a painted axis. It is the composition of a positive bias with a selective flip.
If R flipped all three coordinates, the hinge would vanish and reconstruction would have no residual to stand on. If R flipped nothing, expansion would hit the shell and stall or leak. If the mediator could turn off, every vertex would have to store a full independent triad and the ray would stop being derivable. The asymmetry is the whole trick. Three in one, and only one of the three is allowed to reverse.
From inside the cube you see three faces at a time — a now-slice. The other three faces are not missing. They are implied by the hinge plus R. That is the same split a block universe makes between a lived present and a structured bulk, written here as an operator instead of a metaphor. The hidden faces hold already-reflected depth. The visible faces are what the shell is willing to show.
The mediator is the least glamorous piece and the one the rest cannot spare. Along a ray it is constant. It is the on-only layer: the coordinate you do not re-measure because it is defined to be present. Later notes called it grey, then pink, only so it would not vanish against white paper. The color is not the physics. Invariance is the physics.
So the motion is simple to say and hard to undo. The core tilts. Expansion runs out. R turns that component at the skin. What cannot honestly resolve does not travel back out as a lie. It folds inward. Essay 3 is that fold. Essay 4 is how a discrete cube stores the same rule without writing every cell. This essay only has to hold the hinge.
A closed box with a source still needs a law at the wall. The reflector is that law: one flip, one untouched hinge, one shaped return. Direction falls out of the geometry. Nothing extra is assumed.
The Onion is still reflecting its own core.