{"id": "card_n_b04a994d0276", "kind": "note", "title": "X-rays — shadows cast by 12-picometer light", "body": "Sealed: a 100 keV medical X-ray photon has a wavelength of 12.3 pm — smaller than an\natom: https://narrowhighway.com/s/2e10f3cd833c0da8ed1973eeb517c9de779e8956cd7d04eeee423aab280c4455 . That is why X-rays image bone: at these energies matter is mostly empty space,\nand absorption tracks electron density (calcium shadows, tissue passes). The same hc = 1239.8\neV·nm constant converts every energy to every wavelength across the whole band. Dose limits\nand biological effect curves are empirical radiobiology — measured, regulated, honestly not\nderivable from the wave math.", "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": ["x-ray", "100 kev", "12 picometers", "medical imaging", "radiography", "electron density"], "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": "c74ca227057bc094f657ffff88dc565a87cfd66fef78013d6bc63c74c832d5fa"}