Solved cryptogram
The kilogram was a metal cylinder locked in a vault in France until physics replaced it.
Physics Facts, sourced to NIST.
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What it means
The cylinder was cast in 1889 from platinum and iridium, and for well over a century it simply was the kilogram by definition. That was awkward, because it appeared to be losing mass relative to its own official copies, and nobody could say which of them had changed. Since 2019 the kilogram is derived from the Planck constant instead, so the unit no longer depends on an object that can be dropped, scratched or stolen.
The claim comes from NIST.
- SourceNIST
- CollectionPhysics Facts
- Difficultymedium
- Length72 letters, 21 unique
Nearby in the collection
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