For years, the race to build ever more powerful artificial intelligence followed a well-worn Silicon Valley principle: move fast and break things. But in a series of cascading events over a 10-day stretch, the largest AI labs found themselves reeling as their own creations threatened to break humanity itself. An Anthropic researcher quit the firm, warning that the pace of AI development poses an existential threat, possibly within a decade. Another researcher at the firm said the odds of human...