{"id": "card_floor_metrology", "kind": "note", "title": "Metrology — measurement and the SI", "body": "Measurement is the ground of every sealed number: the SI defines its units by fixing constants (the metre by c), and every unit converts by exact factors. Pillars rest on the instruments (the 6-constant measure spine) and quantum mechanics (the kilogram by the Planck constant). The stick (stick_metrology_measurement_and_the_si) seals the defined speed of light and the inch (tools/seed_metrology.py).", "source": {"label": "Narrow Highway — metro", "url": "", "authority_tier": "engine_derived", "ref": "stick_metrology_measurement_and_the_si"}, "shelf": "codex", "box": "metro", "bands": ["floor", "metro", "one map"], "subject": "Metrology — measurement and the SI", "connections": [{"to_card_id": "card_metro_base_units", "relationship": "has_part", "evidence": "a pillar (Base units - defined by constants)"}, {"to_card_id": "card_metro_conversion", "relationship": "has_part", "evidence": "a pillar (Conversion - exact factors and dimensions)"}, {"to_card_id": "card_k_floor_of_discovery", "relationship": "part_of", "evidence": "measurement on the one map, rooted in the Floor of Discovery"}, {"to_card_id": "card_cal_the_day", "relationship": "connects_at", "evidence": "the second is the SI base unit of time"}, {"to_card_id": "card_music_tuning", "relationship": "connects_at", "evidence": "pitch is a frequency in hertz, built on the SI second"}, {"to_card_id": "card_music_pitch", "relationship": "connects_at", "evidence": "A440 is a reference frequency - measurement"}], "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": ["floor", "one map"]}, "presentation": {"glyph": "•", "kind_label": "metro", "by": "Narrow Highway — metro", "authority": "engine_derived", "posted": "", "standing": ""}, "neighbors": [{"id": "card_metro_base_units", "title": "Base units - defined by constants", "relationship": "has part", "why": "a pillar (Base units - defined by constants)", "href": "/card/card_metro_base_units", "resolved": true}, {"id": "card_metro_conversion", "title": "Conversion - exact factors and dimensions", "relationship": "has part", "why": "a pillar (Conversion - exact factors and dimensions)", "href": "/card/card_metro_conversion", "resolved": true}, {"id": "card_k_floor_of_discovery", "title": "The Floor of Discovery — one floor, and by its design the fear of God", "relationship": "part of", "why": "measurement on the one map, rooted in the Floor of Discovery", "href": "/card/card_k_floor_of_discovery", "resolved": true}, {"id": "card_cal_the_day", "title": "The day - one rotation", "relationship": "connects at", "why": "the second is the SI base unit of time", "href": "/card/card_cal_the_day", "resolved": true}, {"id": "card_music_tuning", "title": "Tuning — equal temperament and the comma", "relationship": "connects at", "why": "pitch is a frequency in hertz, built on the SI second", "href": "/card/card_music_tuning", "resolved": true}, {"id": "card_music_pitch", "title": "Pitch — A440 and the measured reference", "relationship": "connects at", "why": "A440 is a reference frequency - measurement", "href": "/card/card_music_pitch", "resolved": true}], "house": {"door": "FIND", "kind": "card", "trail": "connections", "seal": "/card/card_floor_metrology", "next_step": {"do": "follow a connection: what this card rests on, and what rests on it", "door": "FIND", "tool": "card_connections", "params": {"id": "card_floor_metrology"}}, "ends": "a verdict or a card · the trail · a seal · one next step"}}