It did not take much for the euphoria over artificial intelligence (AI) to turn into alarm. On January 27th stockmarkets in America and Europe convulsed. The share price of Nvidia, America’s AI-chip champion, fell by 17%, erasing $600bn of market value, the biggest one-day loss in the history of America’s stockmarket. Other businesses in the AI supply chain, from data-centre landlords to makers of networking gear, suffered a similar fate.