Over 850 public figures, including AI leaders, have urged a slowdown in the development of superintelligence due to concerns about losing control over AI systems. Notable signatories include Geoffrey Hinton, Yoshua Bengio, Steve Wozniak, and Richard Branson. The letter highlights risks such as economic obsolescence, loss of freedoms, and potential human extinction, calling for a prohibition on superintelligence development until safety is ensured.