Physics from Finite Validation: The Solitaire of Forces — Reading the Four Interactions Through Finite Validation

This fourth work of the series turns from recovering physics to reading it: it asks what makes a force a force, and sorts the four fundamental interactions by a proposed pair of criteria. The standard five-entry passport (carrier, range, source, relative strength, role) is simplified, through the lens of the self-validating world, to two: a fixation-label/conductor (one entity — charge is the capacity to emit and absorb its carrier) and a decay profile (how the interaction changes with separation). By this pair: gravity is recovered (the delay-gradient of Paper 1); electromagnetism has label and conductor, with the 1/r^2 profile a debt; the strong reads as a candidate interference of two profiles (a short repulsion and a long attraction), giving a trough with a numerical attractor r* ≈ 7.17 confirmed in-model — though that the two profiles are specifically gravity and electromagnetism is not realised (the long profile is a phenomenological proxy). The weak interaction's decay channel is reclassified, within this scheme, as template relaxation rather than a binding force — a reading of one face, not a theory of the weak sector (scattering, neutrinos, CP, electroweak structure are untouched); its lifetime hierarchy (a third-decimal barrier shift → fourfold median lifetime) is confirmed in-model. Relaxation is offered as identical to entropy at two levels of description, with an in-model H-test (a localised disturbance spreads irreversibly to equipartition, energy conserved). A master figure places the forces as Tier 0 of the cumulative ladder. A clearly-marked programme-level section reads binding above the physical tier; it carries no numerical content. The work's load-bearing debt is named throughout: the bridge that would turn the interference-probe into a mechanism. The record contains two files: the main article and the Numerical Companion (full protocols, seeds, per-result status labels). Code: https://github.com/ivan-denysov/finite-validation-forces