Atomic-clock realization of the second
A primary caesium frequency standard relates its oscillator to the defining unperturbed Cs-133 hyperfine transition by estimating and correcting design-dependent shifts, including atomic-motion Doppler and thermal blackbody effects.
Key knowledge
A primary caesium frequency standard relates its oscillator to the defining unperturbed Cs-133 hyperfine transition by estimating and correcting design-dependent shifts, including atomic-motion Doppler and thermal blackbody effects. The realized unit is local proper time with a finite uncertainty; transfer and comparison introduce additional effects.
Conditions and scope
- The existing defining frequency remains exact; a physical clock is perturbed and requires an uncertainty budget.
- A local proper-second realization and comparison to distant clocks/time scales require different relativistic corrections. This record does not claim a current best-clock performance or a redefinition.
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): Sections 3.1 and 3.1.1, pages 1–2: ideal unperturbed atom, local proper time, Doppler/blackbody corrections; numerical 2017 performance and later time-scale statistics excluded.
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-atomic-clock-realization
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- university-core.1
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- University core expansion