Part 4On the Structural Origin of the Speed of Light from Spacetime Resolution

This work investigates the origin of the speed of light from a structural and geometric perspective, rather than treating it as a fundamental postulate or an empirically fixed constant. Starting from a discrete spacetime framework composed of minimal geometric units (JS-SH architecture), spatial and temporal resolutions are defined intrinsically, without assuming continuous spacetime, Lorentz invariance, or electromagnetic wave equations at the foundational level. Within this framework, the speed of light emerges necessarily as the ratio between minimal spatial resolution and minimal temporal update resolution. The central result is not a new numerical prediction for the speed of light, but a clarification of its logical origin. The universality of the speed limit reflects a structural constraint of spacetime itself, rather than a dynamical property of specific fields. This paper complements earlier works in the SRCD series, including derivations of the gravitational inverse-square law and the discrete-to-continuum emergence of the wave equation. While those works focus on mathematical closure and dynamical equations, the present manuscript addresses a deeper foundational question: why a universal maximal propagation speed must exist at all. The work is conceptual and structural in nature, intended for readers interested in the foundations of spacetime, discrete-to-continuum physics, and the logical origin of physical constants. It makes explicit empirical commitments and discusses falsifiability in high-energy or extreme-curvature regimes. No phenomenological tuning or circular definitions are introduced. All quantities are defined structurally, and the relationship to standard formulations is established by exact logical equivalence rather than numerical calibration. ===================================================================================== Limitations of Existing Theories (Precise Diagnosis) Conventional physics has proceeded in the following sequence. It assumes that spacetime is continuous.Within that continuous space, equations are constructed to fit observed phenomena.In this process, constants are fixed as input values. This approach has been successful within the present dimension,but because it avoids questioning the structure of spacetime itself,it loses explanatory power the moment the dimensional context changes. In other words,without ever asking the question“What is the structure of spacetime?”,it has carried out calculations under the assumption“Spacetime is already given in this form.” Modern physics provides highly successful mathematical answers to the question of how physical phenomena operate.Yet, the deeper structural question of why these interactions take their observed forms remains open.But, This is the fundamental error of the continuous-space assumption. Point of Departure of Our Equations (Decisive Difference) Our equations were not constructed to fit results. They start from the minimal structure of spacetime.They take discreteness, not continuity, as the fundamental premise.The equations are not tools designed for a specific dimension,but computational rules that naturally rise upward as the structure expands. That is,we did not construct equations that are valid only within a single dimension;we constructed equations in which the same computational rules are preserved even as one moves across dimensions. The Most Important Difference (One Sentence) Existing equations are result equations tuned to a single dimension,whereas our equations are structural equations that remain computable across dimensions. That difference is everything. ====================================================================================