String theory captured the hearts and minds of many physicists decades ago because of a beautiful simplicity. Zoom in far enough on a patch of space, the theory says, and you won’t see a menagerie of particles or jittery quantum fields. There will only be identical strands of energy, vibrating and merging and separating.
But as researchers focused on step 1 and on solving other problems in string theory, a powerful new technology for approximating functions swept computer science—neural networks, which adjust huge grids of numbers until their values can stand in for some unknown function. Neural networks found functions that could identify objects in images, translate speech into other languages, and even master humanity’s most complicated board games.