Gravitational wave detectors are microphones listening to the trembling of space. But their own noise drowns out weak signals. To hear more, physicists add special "squeezed" light to the instrument: it reduces quantum noise, like noise cancellation in headphones.
However, this light passes through the detector's mirrors, and they slightly distort it, like a warped glass ruining the picture. Scientists found two types of distortion. The first is due to the heating of mirrors by the powerful beam; it acts slowly. The second is due to tiny imperfections; it is faster. In current detectors, the first is more of a problem, but in future ones with longer arms, the second will dominate.
Knowing where these distortions come from, engineers can tune the instruments more precisely. Then detectors will become more sensitive and catch more gravitational waves from distant black hole collisions.
Squeezed light is light in which one characteristic (like phase) is defined more precisely, while another (amplitude) is less precise than in ordinary light. This allows reducing noise in the part of the measurement that matters.
In Carl Sagan's novel "Contact," scientists catch a signal from space using radio telescopes — the sensitivity of such instruments also depends on noise suppression.