Is the fine-structure constant exact?

The recorded CODATA 2022 example includes a nonzero standard uncertainty. Preserve that uncertainty rather than labelling the value exact.

Does Koskamo independently measure these constants?

No. It reproduces the named NIST CODATA source and checks the import against that source. It does not independently verify the underlying measurements.

Will the request always return this document version?

No. A new lookup searches current published content. The recorded example links a specific historical document version; retain the version actually returned by your own request.

Constants with context.

Retrieve the fine-structure constant from CODATA 2022, with its uncertainty and a versioned citation.

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Choose the right quantity

Scope the query to codata-constants and check the returned document title. The fine-structure constant and its inverse are different quantities; similarity ranking can return both. Use the matching record, not simply any number in the response.

Preserve units and uncertainty

The recorded example is dimensionless and includes a standard uncertainty and a relative uncertainty. Keep those labels with the value. Do not turn a missing unit into an assumed unit, round away the uncertainty, or describe a measured value as exact.

NIST CODATA source

Identify the release

This dataset reproduces CODATA 2022 recommended values. Its Koskamo document version records the published text, not a new CODATA release or measurement. Check the original source when freshness matters.

How source imports are checked

Try the lookup

Run this in a POSIX shell with curl. Public reads need no account or API key.

Lookup command

curl --fail-with-body 'https://koskamo.com/api/v1/retrieve' -H 'Content-Type: application/json' --data-raw '{"query":"fine-structure constant","dataset":"codata-constants","top_k":3}'

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Read the returned evidence

Selected fields from the first passage returned on 2026-10-04. This is a recorded example; current versions and ranking may change. A response can contain other matches, so check the title and text before using a passage.

Recorded passage

{
  "text": "fine-structure constant = 7.297 352 5643 × 10⁻³ (CODATA 2022 recommended value, NIST)\n\n- Value: `7.2973525643e-3`\n- Standard uncertainty: `1.1e-12` (relative 1.5 × 10⁻¹⁰)\n- Unit: none (dimensionless)\n- Also known as: Sommerfeld constant; alpha",
  "datasetSlug": "codata-constants",
  "datasetVersion": 468,
  "documentId": "36a45e39-7fb0-42ec-8431-e1920ac9dea6",
  "documentTitle": "fine-structure constant",
  "documentVersion": 2,
  "sourceUrl": "https://physics.nist.gov/cuu/Constants/Table/allascii.txt#codata-2022"
}

Keep the citation with the answer

Keep documentId and documentVersion together with the dataset slug, document title, and original source URL. The dataset version describes the collection; it is not the document version. Preserve this evidence through summarization and show it with the final answer.

Versioned citation

fine-structure constant, document v2, codata-constants. https://koskamo.com/data/datasets/codata-constants/documents/36a45e39-7fb0-42ec-8431-e1920ac9dea6?version=2 Source: https://physics.nist.gov/cuu/Constants/Table/allascii.txt#codata-2022

Read the cited version Read the original source

An empty passages array means there is no returned evidence to cite. An HTTP error is a failed lookup, not an empty result. On 429, respect Retry-After; on other failures, report the failure instead of inventing a source.

Frequently asked questions

Is the fine-structure constant exact?: The recorded CODATA 2022 example includes a nonzero standard uncertainty. Preserve that uncertainty rather than labelling the value exact.
Does Koskamo independently measure these constants?: No. It reproduces the named NIST CODATA source and checks the import against that source. It does not independently verify the underlying measurements.
Will the request always return this document version?: No. A new lookup searches current published content. The recorded example links a specific historical document version; retain the version actually returned by your own request.