A Unified Description of Inertial and Reactive Motion

Abstract The description of motion in physics is traditionally divided into two distinct regimes: inertial motion, treated as a passive persistence of velocity, and reactive motion, understood as active acceleration through momentum exchange with expelled mass. While operationally successful, this dual description leaves unresolved questions regarding the physical origin of inertia and the deeper relationship between inertia and propulsion. In this work, we propose a unified interpretation of inertial and reactive motion based on a temporal field framework, in which time is treated as a physically responsive quantity characterized by a locally measurable temporal rate τ. The central dynamical relation, F = − m c² ∇ ln τ expresses force as a response to spatial gradients of the temporal rate. Within this formulation, inertial motion corresponds to a steady-state interaction with a homogeneous temporal field, while accelerated motion arises from temporal inhomogeneities. Reactive propulsion is reinterpreted as a specific, highly dissipative mechanism for generating localized temporal gradients through irreversible energy redistribution. Classical momentum conservation and the rocket equation are shown to emerge naturally as effective descriptions of this process, demonstrating full consistency with established mechanics. The framework reproduces Newtonian dynamics and the weak-field limit of General Relativity, without introducing new forces or modifying existing field equations. The temporal rate τ\tauτ is defined operationally as a ratio of clock frequencies, making the framework empirically grounded and non-tautological. Clear criteria for experimental falsification are formulated, emphasizing precision time and frequency metrology as the primary testing arena. Rather than proposing an alternative mechanics, the temporal field framework offers a unifying physical interpretation that preserves the empirical content of classical and relativistic theories while clarifying the conceptual continuity between inertial persistence and reactive propulsion