Solved cryptogram
Empty space has a measurable resistance to magnetism, and its value sets the speed of light.
Physics Facts, sourced to NIST.
What it means
A vacuum is not nothing. It has an electric property and a magnetic one, and together they determine how fast an electromagnetic wave can move through it. When Maxwell combined the two in the eighteen sixties the answer came out at the speed of light, which is how physics learned that light is an electromagnetic wave. The connection was one of the great surprises of the century.
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This is not the kind of claim that goes out of date, which is why it was set as a puzzle rather than a fact with a shelf life.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: 75 letters over 20 different ones, graded medium.
- SourceNIST
- CollectionPhysics Facts
- Difficultymedium
- Length75 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.