O.K., DOOMER

Some people want to build ALI. faster. Others want to pull the plug. Who will decide the fate of humanity?

-  ANDREW MARANTZ

Katja Grace’s apartment, in West Berkeley, is in an old machinist’s factory, with pitched roofs and windows at odd angles. It has terra-cotta floors and no central heating, which can create the impression that you’ve stepped out of the California sunshine and into a duskier place, somewhere long ago or far away. Yet there are also some quietly futuristic touches. High-capacity air purifiers thrumming in the corners. Nonperishables stacked in the pantry. A sleek white machine that does lab-quality RNA tests. The sorts of objects that could portend a future of tech-enabled ease, or one of constant vigilance.

Grace, the lead researcher at a nonprofit called A.I. Impacts, describes her job as “thinking about whether A.I. will destroy the world.” She spends her time writing theoretical papers and blog posts on complicated decisions related to a burgeoning subfield known as A.I. safety. She is a nervous smiler, an oversharer, a bit of a mumbler; she’s in her thirties, but she looks almost like a teen-ager, with a middle part and a round, open face. The apartment is crammed with books, and when a friend of Grace’s came over, one afternoon in November, he spent a while gazing, bemused but nonjudgmental, at a few of the spines: “Jewish Divorce Ethics,” “The Jewish Way in Death and Mourning,” “The Death of Death.” Grace, as far as she knows, is neither Jewish nor dying. She let the ambiguity linger for a moment. Then she explained: her landlord had wanted the possessions of the previous occupant, his recently deceased ex-wife, to be left intact. “Sort of a relief, honestly,” Grace said. “One set of decisions I don’t have to make.”