Jiro Soda

A translator who can hear every rustle in the hall cannot translate a single word. Gravitational waves passing through ordinary space are much the same: they stay invisible to light, because conservation of energy and momentum forbids a photon from turning into a graviton. But put the light in a box with conducting walls, and the rules change.

A massive aluminum cylinder weighing a ton hangs in a vacuum. A gravitational wave, a ripple in spacetime, passes through it, and the bar begins to tremble almost imperceptibly. That trembling can be heard as sound: gravitational waves turn into a phonon — a quantum of sound vibrations.