The Geocentric Pendulum & the Kinetic Nadir: A Unified Framework for Gravity‑Coupled, Event‑Driven Spatial Interaction

This paper unifies two previously proposed theoretical frameworks — the Geocentric Pendulumthesis and the Kinetic Nadir — into a single, coherent architecture for a new class ofgravity-coupled, event-driven spatial interfaces. The first half establishes the neurophysiologicalfoundation: the human nervous system incorporates a rigid internal model of Earth’s gravitationalfield, and interfaces that neglect this absolute reference frame operate in measurable contradictionwith the operator’s physiology. Evidence from vestibular psychophysics, locomotion biomechanics,tactile coding of anisotropy, and impedance control is synthesized to argue that a pendular interfacewith real inertial feedback offers ecological fidelity potentially superior to symmetric digitalperipherals in continuous three-dimensional tasks. The second half introduces the Kinetic Nadirprimitive — the instant of peak tangential velocity in an oscillatory or rhythmic movement — as theoperational mechanism that translates the Geocentric Pendulum thesis into a tractable interfaceprotocol. Rather than tracking continuous positional trajectories, the system samples exclusively atkinetic peaks, producing natural data compression, inherent noise reduction, and alignment with theintermittent structure of human motor control. A parametric excitation model with an explicitgoverning equation shows how grip pressure and micro-slip act as manipulable input channels,while Continuous Wavelet Transform (CWT) decomposition theoretically isolates foursimultaneous sensorimotor layers — body locomotion, arm, wrist, and fingers — forming asensorimotor polyrhythm. An informal viability check using a blunt, sheathed 5-inch kitchenknife with protective eyewear as the only available means is described; the technicalspecifications for a proper Pendular Inertial Proxy (PIP) are provided as the safe, standardizedalternative for future demonstrations. A validation roadmap is proposed, and speculativeextrapolations to fluid media, aerospace vehicles, and multi-body systems are anchored in knownphysical systems. No controlled experiments with participants have been conducted; allperformance claims remain working hypotheses awaiting empirical verification.