The Ontology of Particle: Localized Constrained-State Excitations, Persistence-as-Fixity and the Nodes of the Constraint Network

What is a particle? In classical physics, particles were tiny, indivisible bits of matter. In quantum field theory, particles became excitations of underlying fields. Yet the ontological status of the particle—what it is, not merely how it behaves—remains unresolved. Energy-Efficiency Theory (EET) provides a first-principles answer grounded in the dynamics of constraint networks. A particle is a \textbf{localized, stable excitation of constrained-state energy}—a persistent Type I constraint that manifests as a discrete node in the constraint network. It is not a separate substance from the field but the field's complementary mode: the field is the continuous, free-state distribution; the particle is the…