James H. Edgar

A tuning fork cut from a perfect metal rings at a single frequency. Its sound is as pure as a mathematical formula. But clamp it in a vise or dip it in a viscous liquid, and the tone smears, picks up noise, and loses its sharpness. The nucleus of scandium-45 behaves much the same way when placed in a crystal lattice.

Tiny defects in a boron nitride crystal act as ultra-sensitive magnetic sensors. But their signal resembles a radio with a mistuned antenna: instead of a clear note, you get a broad, noisy range.