# Tiesinga:2021 — CODATA 2018 recommended values

**Citation.** E. Tiesinga, P. J. Mohr, D. B. Newell and B. N. Taylor,
"CODATA Recommended Values of the Fundamental Physical Constants: 2018",
*Reviews of Modern Physics* **93**, 025010 (2021).

**Access.** Open. NIST's archived listing for this adjustment is at
<https://physics.nist.gov/cuu/Constants/ArchiveASCII/allascii_2018.txt>.

## What this reference supports in the treatise

The chapters that quote the 2018 adjustment rather than the 2022 one:
projectile motion, Cavendish, electromagnetism, Stern--Gerlach, precision
spectroscopy, Brownian motion and superconductivity.

`../data/Tiesinga_2021.csv` holds the 21 constants those chapters quote.

## Provenance

- **Fetched from NIST's archived ASCII listing** by
  `tools/bibcheck/build_pdg_codata18.py`, read with the fixed-width columns
  the file uses. The only edit is removing NIST's digit-separating spaces.

## Caveats

- **Superseded by CODATA 2022** (`Mohr:2025`). The two adjustments differ in
  the last digits; a precision claim that mixes them is wrong. Check a
  chapter's number against the adjustment it actually cites.
- The 2019 SI redefinition is already in force in this adjustment, so *c*,
  *h*, *e*, *k* and *N*_A are exact here too.