She left the AI race over her health. Two days later, OpenAI had her back.

On Tuesday, Lilian Weng said she was stepping down from Thinking Machines Lab because the job was making her ill. On Wednesday, she was back at OpenAI. Weng co-founded Thinking Machines Lab with Mira Murati, OpenAI’s former chief technology officer. She is rejoining OpenAI to work on recursive self-improvement, or using AI models to build better AI models, The Information reported. Recursive self-improvement, using AI to build better AI, is one of the most consequential and contested problems in the field. Her recursive self-improvement brief puts her at the very edge of the technology.