Solved cryptogram
A neutron is slightly heavier than a proton, and that tiny gap is why free neutrons decay.
Physics Facts, sourced to NIST.
What it means
The difference is about a tenth of a percent, and the whole character of matter depends on it. Because a neutron outweighs a proton plus an electron, a neutron sitting on its own can turn into those two and release energy, which it does with a half life of roughly fifteen minutes. Bound inside a nucleus it is usually stable, since the decay would cost energy rather than release it.
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This is not the kind of claim that goes out of date, which is why it was set as a puzzle rather than a fact with a shelf life.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: 72 letters over 19 different ones, graded medium.
- SourceNIST
- CollectionPhysics Facts
- Difficultymedium
- Length72 letters, 19 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.
- NISTmedium, 72 letters
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- Royal Society of Chemistrymedium, 68 letters
- NISTmedium, 75 letters