Abstract
This article provides the first complete structural analysis of all known spectral, geometric, motivic, adelic, p‑adic, and tropical approaches to the Riemann Hypothesis (RH). Twenty‑five paradigms are evaluated against four structural requirements — S1 (linear encoding), S2 (discrete spectrum), S3 (phase preservation), and S4 (analytic compatibility). No paradigm satisfies all four simultaneously. Each fails by one of three universal mechanisms: Identity, Circularity, or Structural Obstruction. The failures follow a deterministic pattern: every triple of requirements is realizable, but the fourth is always violated. Three empirical laws hold uniformly across all paradigms: complex spectral theories force quadratic encoding; non‑archimedean structures encode only local data; and any condition enforcing ℜ ( 𝜌 𝑘 ) = 1 / 2 is equivalent to RH. The central tension is the phase–factor‑2 dichotomy: linear encoding destroys phase, while phase preservation forces quadratic encoding. The article formulates the Structural Conjecture: within known mathematics, no framework can satisfy all four requirements simultaneously. This does not imply impossibility of proving RH; it implies that all known spectral–geometric routes are structurally blocked. A successful approach requires a new hybrid mathematical structure combining linearity, phase, compactness, and analytic continuation — a structure not yet present in current mathematics.



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