From Google to galaxy clusters

AI has numerous uses, from managing social media to detecting warps in space-time

AI algorithms used by Facebook and Google have been employed by astronomers to study a phenomenon that Albert Einstein proposed in his theory of general relativity over 100 years ago. In October 2017, a team of astronomers from the universities of Groningen, Naples and Bonn developed a method of detecting gravitational lenses using the same AI as the social network and search engine giants.

Gravitational lensing is an effect caused by an enormous mass warping space-time: massive objects such as galaxy clusters can be used as a sort of cosmic magnifying glass to observe more distant objects.

The AI algorithm the astronomers used is called a convolutional neural network and works on the same formulae employed by Google in 2017 to win a game of Go against the world’s best human player. Facebook uses the same algorithms to compile data on the images that appear in its users’ timelines.

The astronomers trained their AI using millions of images of gravitational lenses. Normally, human astronomers would examine all the images to look for potential candidates, but the AI was able to find 761 examples of gravitational lensing independently in a patch of sky 22 square degrees across – just over 0.5 per cent of the total area. The astronomers then narrowed down to 56 candidates awaiting confirmation through telescopic observation.

Some of the fabricated images of gravitational lenses that the Groningen, Naples and Bonn astronomers used to train their neural network to recognise the phenomenon Three of the gravitational lenses discovered by the convolutional neural network