This document presents the core geometric intuition behind Memory Engines and the Reciprocator. For the precise mathematical specification and implementation details, see reciprocator.md and the code in model.py (see https://github.com/geometer-jones/reciprocator-lm.git).
Imagine an apple falling from a tree. Gravity pulls it faster and faster. Every prior instant of the gravitational field is perfectly preserved in its present velocity; nothing is lost. Yet the apple feels nothing. It does not notice,