The prediction phase of the Theory of Imbalance of Energy (TIE v2.1) established a closedset of structural constraints implied by finite interaction propagation, without reference to physical mechanisms or ontology. These constraints include delayed corrective influence, limits oncoordination, and the emergence of persistent bounded domains. The present paper initiatesthe explanatory phase (TIE v2.2) by addressing the minimal explanatory requirement left openby the prediction layer: what must physically exist for interaction, delay, and persistence tooccur at all.This work demonstrates that the v2.1 constraints cannot be realized by purely abstractrelations, geometric descriptions, or action-at-a-distance formulations. Finite propagation anddelayed correction require a physical substrate capable of local response, temporary imbalancestorage, and finite-speed transmission of disturbance. The paper derives the minimal propertiessuch a substrate must possess while deliberately avoiding premature identification with knownphysical constructs. No claims are made here regarding gravity, particles, quantum behavior, orcosmology; these are deferred to subsequent papers where they arise as unavoidable consequencesof the substrate established in this work.