Editing Openai/6897769e-4ee4-800f-aba5-69cca34f701c (section)

=== - Spin is the way a local boundary (the electron shell, or the spherical wavefront) stores and transforms orientation information when the EM tangential field is absorbed and re-emitted. - Photon spin = rotation of the tangent E-vector on the spherical wavefront (standard polarization/helicity). Wikipedia<ref>{{cite web|title=Wikipedia|url=https://en.wikipedia.org/wiki/Photon_polarization|publisher=en.wikipedia.org|access-date=2025-12-16}}</ref> - Electron spin-½ = an antiperiodic topological phase living on the shell (spinor bundle / double-cover geometry), so a 360° rotation flips the phase → requires 720°. Rochester School of Arts & Sciences<ref>{{cite web|title=Rochester School of Arts & Sciences|url=https://www.sas.rochester.edu/pas/assets/pdf/undergraduate/su-2s_double_covering_of_so-3.pdf|publisher=Rochester School of Arts & Sciences|access-date=2025-12-16}}</ref> - Effective spin-2 / gravity = the coherent, symmetric second-order response of many photon absorption-re-emission events at boundaries (and modern “double-copy” amplitude results give formal support that “two gauge quanta can square into a graviton-like degree”). Physical Review Links<ref>{{cite web|title=Physical Review Links|url=https://link.aps.org/doi/10.1103/PhysRevLett.105.061602|publisher=Physical Review Links|access-date=2025-12-16}}</ref>arXiv<ref>{{cite web|title=arXiv|url=https://arxiv.org/html/2403.08637v1|publisher=arxiv.org|access-date=2025-12-16}}</ref> ===