How did a little-known Chinese start-up cause the markets and U.S. tech giants to quake? Here’s what to know. By Cade Metz Reporting from San Francisco Tech stocks tumbled. Giant companies like Meta ...

Dario Amodei, the C.E.O. of the artificial-intelligence company Anthropic, has been predicting that an A.I. “smarter than a Nobel Prize winner” in such fields as biology, math, engineering, and ...