Solved cryptogram
A second is no longer a slice of the day. It is a fixed count of vibrations in a cesium atom.
Physics Facts, sourced to NIST.
What it means
Tying time to the Earth turned out to be a bad idea, because the planet's spin is uneven and slowly slowing. A cesium atom is not. Electrons in cesium flip between two energy states at a rate that is the same everywhere in the universe, and the second is defined as a specific number of those flips. Clocks built this way drift by less than a second over the age of the solar system.
The claim comes from NIST, and the page it comes from was read on 2026-08-27 to confirm it still says this.
This is not the kind of claim that goes out of date, which is why it was set as a puzzle rather than a fact with a shelf life.
Solve it yourself
This fact is a cryptogram here: 71 letters over 20 different ones, graded medium.
- SourceNIST
- CollectionPhysics Facts
- Difficultymedium
- Length71 letters, 20 of them different
Nearby in the collection
The facts either side of this one.
About as hard as this one
Scored closest to it by the model behind our guide to solving cryptograms.