How Mirror Misalignment Tangles Light in Gravitational-Wave Detectors
Light in a gravitational-wave detector races through multi-kilometer tunnels, bouncing off mirrors. A perfectly uniform beam resembles a smooth sheet held by its corners. But if one mirror tilts by the width of an atom, the sheet develops wrinkles: 'parasitic' patterns, more complex light spots, awaken in the beam.
Previously, such wrinkles were dismissed as noise.