{"id": "card_n_08a41f6b5ab9", "kind": "note", "title": "Gamma rays — the spectrum meets the nucleus", "body": "At the top of the dial the photons come from nuclear transitions and antimatter.\nSealed: the electron's rest energy m_e·c² computes to 510.99 keV (m_e measured by CODATA;\nc, h, e exact by definition): https://narrowhighway.com/s/2e10f3cd833c0da8ed1973eeb517c9de779e8956cd7d04eeee423aab280c4455 — so when an electron meets a positron, two 511 keV\nphotons fly apart back-to-back, and a PET scanner draws the body by catching those pairs.\nCobalt-60's 1.17/1.33 MeV lines, cosmic gamma bursts — the wavelengths are shorter than\nnuclei. Here the spectrum walk hands off to the nuclear fleet: decay chains and half-lives\nverify in-domain (NUCLEAR_VERIFY), and the boundary stays honest — which isotope emits what\nis measured nature, never derivation.", "source": {"label": "Concordance assay — 2026-07-09", "url": "https://narrowhighway.com/s/2e10f3cd833c0da8ed1973eeb517c9de779e8956cd7d04eeee423aab280c4455", "ref": "spectrum_walk_high", "authority_tier": "engine_derived"}, "shelf": "science", "box": "radio_spectrum", "bands": ["gamma rays", "511 kev", "annihilation", "pet scan", "electron rest mass", "cobalt-60", "nuclear"], "connections": [], "author": "engine", "created_at": "2026-07-10T01:12:51.215332+00:00", "updated_at": "2026-07-10T01:12:51.215332+00:00", "visibility": "public", "lifecycle_stage": "public", "volatility": "permanent", "surface": "secular", "metrics": {"paperclips_count": 0, "helpful_count": 0, "not_helpful_count": 0, "cite_count": 0, "walks_through_count": 0, "flagged_count": 0}, "source_hash": "f4a8afcf6c0a1c947729cb78bb823c9956978448ae0ea8d61cda0fdd8bbd0be5"}