The Icosahedral Cascade: A Survey of A₅ and 2I Across Mathematics and Physics

A survey documenting the appearance of the alternating group A₅ (order 60), the binary icosahedral group 2I (order 120), and the associated E₈ structures as essential elements in eleven independent domains of mathematics and physics: Galois theory, the ADE classification, sphere packing, cosmic topology, neutrino flavor symmetry, nuclear skyrmions, quasicrystals, Painlevé transcendents, virology, base-60 arithmetic, and 2D conformal field theory. No unifying theory is proposed; the pattern is documented and the question is left open. Ver. 2.2 ---Ξυα Mσςς[email protected]