Exact SI definition and uncertain realization
Fixing a defining constant's numerical value makes that SI definition exact; it does not make an experiment or transferred standard exact.
Key knowledge
Fixing a defining constant's numerical value makes that SI definition exact; it does not make an experiment or transferred standard exact. A practical realization establishes a quantity value consistent with the definition and an associated uncertainty, and different methods can realize the same unit.
Conditions and scope
- Use the current SI definition and the particular realization's model, corrections and traceability.
- A mise en pratique describes recognized methods, not an exhaustive restriction on every possible realization; quoted historical performance values are not guaranteed current uncertainty.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
SI second: mise en pratique (2019): Section 1 and §3.1: meaning of realization, method nonexhaustiveness and finite experimental uncertainty.
2026-10-10 · Independent AI editorial review: Independent root AI editorial review of all29 authored Measurement claims/conditions, displayed equations and37 origin relations. The original26 claims were read against41 primary source sections; all5 requested corrections and the3 affected source bindings were subsequently rechecked. Three actual scalar-nonlinear/vector/dynamic applications were read, independently differentiated or integrated, and checked against the specific additional source material described below. This is reference-content review, not human specialist certification, instrument certification or experimental replication. Full-field sign-off waits for the combined final conceptual matrix. Receipt: measurement-independent-content-review.1.
Entry details
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- measurement-definition-realization
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- university-core.1
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