Scientists at the world's largest gravitational wave observatory have just squeezed light beyond a key quantum limit.
The LIGO detector spots these cosmic ripples from the way they distort space-time as they pass through it. Made up of two intersecting L-shaped detectors — each with two 2.48-mile-long arms and two identical laser beams inside — the experiment is designed such that if a gravitational wave passes through Earth, the laser light in one arm of the detector will get compressed while the other expands, creating a tiny change in relative path lengths of the beams arriving at the detector.
High frequency noise comes from tiny particles randomly popping in and out of existence. Low frequency noise comes from the rumble of reflecting light particles that cause the mirrors to wobble. Both sources limit the number and types of gravitational waves LIGO can detect.