The Sun and the Moon cause the mirrors to sway, and magnets are required to restore the mirrors to their baseline location. There are also seismometers to detect local motions of the Earth with attendant hydraulic systems to compensate for those displacements. All of this constitutes forms of noise, to be distinguished from a bona fide signal. We listen to the raw sounds of the instrument. It whirs with the tidal pull of the celestial bodies, the grumbling of a still-settling Earth, the remnants of heat in the elements, the quantum vibrations and the pressure of the laser.
