We could spot a new type of black hole thanks to a mirror-wobbling AI

The Laser Interferometer Gravitational-Wave Observatory (LIGO) uses lasers and mirrors to look for black holes across the universe, and it turns out a Google DeepMind AI could make it even more sensitive

By Matthew Sparkes

4 September 2025

Black holes produce gravitational waves when they collide

VICTOR de SCHWANBERG/SCIENCE PHOTO LIBRARY

Efforts to understand the universe could get a boost from an AI developed by Google DeepMind. The algorithm, which can reduce unwanted noise by up to 100 times, could allow the Laser Interferometer Gravitational-Wave Observatory (LIGO) to spot a particular type of black hole that has so far eluded us.

LIGO is designed to detect the gravitational waves produced when objects such as black holes spiral into each other and collide. These waves cross the universe at the speed of light, but the fluctuations they cause in space-time are extremely small – 10,000 times smaller than the nucleus of an atom. Since its first observations 10 years ago, LIGO has recorded such signals produced by nearly 100 black hole collisions.

Read more

How a quantum innovation may quash the idea of the multiverse

Advertisement

To do so, the experiment consists of two observatories in the US, each with two arms 4 kilometres long that are set perpendicular to each other. Lasers are beamed down each arm, reflected by precise mirrors at the end and then compared using an interferometer. The length of the arms is changed by a tiny amount as gravitational waves wash over them, and this is carefully recorded to build a picture of the origin of these signals.

The problem is that such demanding accuracy is required that even distant ocean waves or clouds passing overhead can affect measurements. This noise can easily drown out signals, making some observations impossible. Dozens of major adjustments need to be made to filter out the worst of this noise, tweaking the orientation of mirrors and other equipment.

Rana Adhikari at the California Institute of Technology in Pasadena, who worked with DeepMind to develop the new AI technology, says that attempting to automate these adjustments can ironically create more noise. “That controls noise has been bedevilling us for decades and decades – everything in this field has been blocked,” says Adhikari. “How do you hold the mirrors so still without inducing noise? If you don’t control them, the mirrors swing all over the place, and if you control it too much, then it sort of buzzes around.”