Constraint in Fundamental Physics

This work argues that constraint, rather than dynamics alone, constitutes a missing organizing layer in fundamental physics. While modern theories successfully unify interactions and describe evolution within given state spaces, they largely take the admissibility of those spaces for granted. The deepest unresolved problems in physics—low-entropy initial conditions, horizon-bounded information, non-extensive entropy, and the limits of quantum correlations—are not failures of dynamics, but failures to account for how global constraints determine what states and correlations are physically permitted in the first place. The paper formalizes this perspective by treating constraint as pre-dynamical: acting prior to and independently of equations of motion. Physical laws are understood as operating within an evolving set of admissible states and correlations, shaped by global geometric, informational, and causal limits. Entropy is reinterpreted as a measure of admissible capacity, and gravitational phenomena are understood as constraint-generating rather than force-like in origin. From this framing, the work derives a central structural consequence: physical coherence cannot be distributed uniformly or scale-freely. As constraints relax, admissibility opens unevenly, forcing coherence to emerge in discrete stages and migrate across progressively narrower substrates. This provides a unified explanation for area-law entanglement, Page-like information transitions, the breakdown of scale-free expectations, and the increasing fragility of complex systems. No new physical constants, particles, or modified dynamics are introduced. General relativity, quantum mechanics, and thermodynamics remain intact but are reinterpreted as theories operating within constraint-defined admissibility regimes. The paper positions constraint as a foundational concept that complements, rather than replaces, existing frameworks. This work is intended as a foundational contribution, establishing constraint as a candidate primitive for a more complete theory of fundamental physics. Subsequent work will explore concrete applications of this framework to quantum decoherence, gravitational information, and complex adaptive systems.