Inertia Does No Work: An Energy-Constraint Interpretation from Energy-Efficiency Theory

In classical mechanics, inertia is taken as a primitive axiom; in general relativity, inertial motion is geometrized as geodesic motion. Both frameworks describe inertial motion but do not explain why an object maintains its state of motion without continuous energy input. This paper offers an interpretation within Energy-Efficiency Theory (EET). Starting from the three axioms, we interpret inertia as the inherent stability of constrained-state energy to maintain its existing state of motion. Maintaining a state involves no cross-system energy transfer and therefore requires no work; changing a state requires breaking constraints and thus external energy input. We derive the condition for perfect inertia in terms of the experimental time scale: when the inertial decay time τ∼λ0−1eEb/kBTτ∼λ0−1eEb/kBT greatly exceeds the observation time tobstobs, no measurable dissipation occurs. When this condition is violated, inertial leakage occurs. We define the concepts of inertial inheritance and its complement inertial interruption, which underlie the EET analysis of identity and continuity in the companion papers. The framework unifies classical inertia with macroscopic quantum phenomena such as superconductivity and superfluidity, where zero-resistance flow is a direct manifestation of inertial inheritance. This paper is the ontological companion to The Energy-Constraint Interpretation of Inertia, which provides quantitative predictions and experimental protocols.