Fields Medal
Mathematics' most prestigious prize, awarded every four years to researchers under 40.
There is no Nobel Prize for mathematics, and the Fields Medal is what the field uses instead. It is awarded every four years to between two and four mathematicians, with one unusual condition: recipients must be under 40. That makes it a prize for work done early rather than a lifetime award, and it means the list of medallists is a decent map of where mathematics was moving at the time.
It turns up in AI coverage for two reasons. Labs have started recruiting Fields Medalists directly, betting that people who can prove things rigorously are what AI safety research is missing. And mathematics has become the benchmark everyone watches, because it is one of the few areas where an answer can be checked as definitively right or wrong.