A public record of known limits

The verified boundaries
of what is possible.

Limits Registry makes the frontier between achievement and impossibility legible — with sources, proofs, and the people behind every claim.

⌘ K

01Explore the registry

Curated registry

Limits worth knowing

Curated registryUpdated today

LR-001004OPEN limit

The 2022 CODATA recommended value of alpha particle mass in u, retained with its published standard uncertainty.

Recommended reference value4.001 506 179 129

A published value under the current specification, not two opposing bounds.

1 total

= 4.001 506 179 129

EXACT VALUECODATA 2022 recommended value; requires Registry editorial review before publication.Registry database · 2026

SOURCE CONFIRMED

20222022 CODATA recommended valuealpha particle mass in u: 4.001 506 179 129 u