{"id": "card_n_0fd6d5654d74", "kind": "note", "title": "Binding energy — the mass that glue costs", "body": "Weigh a nucleus and it comes up LIGHT: the missing mass is the binding energy,\nE = mc². Sealed: the deuteron (one proton + one neutron) is short 2.224 MeV — the first\nrung of the strong force — and helium-4 binds at 7.074 MeV per nucleon (in-domain):\nhttps://narrowhighway.com/s/8a5e89ab13bc499f39240c64360d90c34a65a291c91c73fcac4fc976131b17c5 . The curve of binding per nucleon rises to IRON-56 and falls after — which is the\nsingle fact that shapes the universe's energy economy: fusing light nuclei releases energy,\nsplitting heavy ones releases energy, and iron is the ash of both fires. The curve's shape\nis measured (every mass in the CODATA/AME tables); its explanation is the strong force.", "source": {"label": "Concordance assay — 2026-07-09", "url": "https://narrowhighway.com/s/8a5e89ab13bc499f39240c64360d90c34a65a291c91c73fcac4fc976131b17c5", "ref": "nuclear_dig", "authority_tier": "engine_derived"}, "shelf": "science", "box": "nuclear", "bands": ["binding energy", "mass defect", "e=mc2", "deuteron", "helium-4", "iron-56", "iron peak", "strong force"], "connections": [], "author": "engine", "created_at": "2026-07-10T01:19:38.918200+00:00", "updated_at": "2026-07-10T01:19:38.918200+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": "8fe3f6be75385fcb09951bac936eef256b61aefa55551db968a48a7064a44284"}