In a weekend in the spring of 2025, a clandestine mathematical conclave convened. Thirty of the world’s most renowned mathematicians traveled to Berkeley, Calif., with some coming from as far away as ...

A.I. search tools, chatbots and social media are associated with lower cognitive performance, studies say. What to do? Credit...Derek Abella Supported by By Brian X. Chen Brian X. Chen is The Times’s ...