Sandy Croatto

At the DESY lab, the ALPS II experiment was launched to hunt for axions — hypothetical ghost particles that might make up dark matter. This invisible mass acts like a skeleton, preventing galaxies from flying apart due to their spin.

A thin film of silicon nitride is stretched over a frame like the skin of a drum. The slightest nudge from gas molecules makes it tremble. A laser beam delivered through a glass fiber picks up that trembling and turns it into a pressure reading. The whole setup fits in a pocket, not on an optical table.