A Thermal Circulation Hypothesis for Matter Cooling and Planetary Motion Integrated theoretical backbone of the Thermodynamic Model

This paper restates the theoretical backbone of the Thermodynamic Model after its development through papers M2 to M11. The model proposes that matter contains organised or confined Thermon structures and that freely propagating Thermon waves form a non-luminous carrier state. Free Thermon propagation is assigned the postulated speed 2c, while the organised electromagnetic state propagates at c. Conversion between these states is proposed near the Sun and at an outer non-retaining condition termed Total Frost. These propositions remain hypotheses rather than measurements. The central revision is a Universal Directional-Pressure Hypothesis. The original model allowed at least nine, and possibly more, external channels. Later papers selected Gaia BH1, Gaia BH2, Gaia BH3, A0620-00 and OGLE-2011-BLG-0462 as a fixed five-direction test set. The five are not replacements for the original nine and are not assigned one-to-one to planets. Each candidate channel retains its own direction, momentum flux, transmission, material coupling and response delay. A body responds to the local momentum deposited in its constituent material. An orbital change depends on the differential response of the body and the Sun, not on a common acceleration shared by both. The revised formulation separates energy flux from force. Heat or energy flux in watts per square metre is not itself a mechanical pressure. For ordinary electromagnetic radiation, momentum transfer follows a measured radiation law. For the proposed Thermon carrier, an energy-momentum relation, scattering law and material-response law remain to be defined. The paper therefore treats Thermon momentum flux as an independent model quantity instead of obtaining it automatically by dividing energy flux by 2c. A conditional inward inverse-square relative acceleration can reproduce conic paths under inertial mechanics, but this is a closure example rather than a derivation from the external channels. Fixed far-source directions alone cannot maintain inward curvature throughout every planetary orbit. A viable model must derive spatial gradients, boundary redistribution or another response that supplies the required relative field while conserving energy and momentum. Concise summaries connect this backbone to M2-M11. A consistency audit standardises terminology, equations, speeds, timescales, source names, assumptions and publication links, and identifies the principal unresolved requirements.