PFUSRC-088 The Topological Mass of Light and Shadow: A Phenomenological Supplement to the Ontology of Mass Origins

PFUSRC-066 defines mass as steady inertial stock formed through topological latching of four-dimensional flow-variable fields constrained by curvature anchors. Mainstream physics relies on a binary “mass-bearing / massless” framework that generates pseudo-questions when evaluating light and shadow: it debates rest mass for perpetually moving photons and attempts to assign mass to shadow, a non-entity topological truncation effect. This paper serves as a phenomenological footnote to mass origin ontology, replacing binary mass judgment with the core criterion of topological latching state to reinterpret light and shadow. Four core conclusions are established. First, photon masslessness does not equate to zero intrinsic mass; photons are unlatching instantaneous projective slices of four-dimensional flow variables carrying only transient topological projective residue without stable inertial mass. Second, measurable equivalent mass observed in light-freezing EIT experiments arises from temporary latching of light’s projective residue onto atomic medium carriers. Third, shadow constitutes negative topological truncation residue rather than absolute nothingness. It carries geometric boundary information marking projection interruption but holds no latching mass. Fourth, light’s positive projective residue and shadow’s negative truncation residue combine to conserve complete topological projective information of regional Topological One, forming symmetric light-shadow topological duality. Thought experiments including flowing water analogy, covered-bowl weighing and radiation pressure measurement verify the proposed topological mechanisms. The universal microscopic critical residual ΔA ≈ 0.0364 unifies macroscopic optical observations and microscopic topological perturbation rules, resolving interpretive gaps in mainstream optics for extreme mass boundary phenomena.