The World's Largest Computer Chip

Deep learning, the artificial-intelligence technology that powers voice assistants, autonomous cars, and Go champions, relies on complicated "neural network" software arranged in layers. A deep-learning system can live on a single computer, but the biggest ones are spread over thousands of machines wired together into "clusters," which sometimes live at large data centers, like those operated by Google. In a big cluster, as many as forty-eight pizza-box-size servers slide into a rack as tall as a person; these racks stand in rows, filling buildings the size of warehouses. The neural networks in such systems can tackle daunting problems, but they also face clear challenges. A network spread across a cluster is like a brain that's been scattered around a room and wired together.