Jacob Tsimerman
Number theorist and Fields Medalist who left the University of Toronto to work on AI safety at OpenAI.
Jacob Tsimerman is a number theorist who won the Fields Medal, mathematics’ highest honour, and was a professor at the University of Toronto. In 2026 he joined OpenAI to work on AI safety, one of the clearest examples yet of labs hiring pure mathematicians rather than machine learning researchers.
His argument for the move is that AI is built empirically. People try things, measure the results, and keep what works, with very little proof about why any of it behaves as it does. That is workable engineering and thin ground for safety, and proving what a system cannot do is a mathematician’s speciality. He co-published a paper in 2025 on so-called omnicide events, scenarios in which AI contributes to human extinction, a framing plenty of researchers dispute. He has said panic is not the right response but that the risks deserve honest assessment.