{"id": "card_metro_base_units", "kind": "reference", "title": "Base units - defined by constants", "body": "Seven SI units built from seven fixed constants: the metre from c (sealed), the kilogram from the Planck constant, the second from caesium. Anchored to nature.", "source": {"label": "Narrow Highway — metro", "url": "", "authority_tier": "engine_derived"}, "shelf": "codex", "box": "metro", "bands": ["metro", "pillar", "base_units", "one map"], "subject": "Base units - defined by constants", "connections": [{"to_card_id": "card_floor_metrology", "relationship": "part_of", "evidence": "a pillar (Base units - defined by constants)"}, {"to_card_id": "card_floor_the_instruments", "relationship": "connects_at", "evidence": "the 6-constant measure spine defines the units"}, {"to_card_id": "card_floor_quantum_mechanics", "relationship": "connects_at", "evidence": "the kilogram is fixed by the Planck constant"}], "author": "engine", "created_at": 0.0, "updated_at": 0.0, "visibility": "public", "lifecycle_stage": "public", "volatility": "permanent", "surface": "secular", "generated": false, "call": "codex.metro", "facets": {"subject": ["base_units", "one map", "pillar"]}, "presentation": {"glyph": "•", "kind_label": "metro", "by": "Narrow Highway — metro", "authority": "engine_derived", "posted": "", "standing": ""}, "neighbors": [{"id": "card_floor_metrology", "title": "Metrology — measurement and the SI", "relationship": "part of", "why": "a pillar (Base units - defined by constants)", "href": "/card/card_floor_metrology", "resolved": true}, {"id": "card_floor_the_instruments", "title": "The instruments — every verifier and validator, and where they join", "relationship": "connects at", "why": "the 6-constant measure spine defines the units", "href": "/card/card_floor_the_instruments", "resolved": true}, {"id": "card_floor_quantum_mechanics", "title": "Quantum mechanics — the quantum and its limits", "relationship": "connects at", "why": "the kilogram is fixed by the Planck constant", "href": "/card/card_floor_quantum_mechanics", "resolved": true}], "house": {"door": "FIND", "kind": "card", "trail": "connections", "seal": "/card/card_metro_base_units", "next_step": {"do": "follow a connection: what this card rests on, and what rests on it", "door": "FIND", "tool": "card_connections", "params": {"id": "card_metro_base_units"}}, "ends": "a verdict or a card · the trail · a seal · one next step"}}