What happened (quiz-caption claim tied to the Fields Medal)

A quiz caption asks readers to identify a woman shown in the image. The caption claims that the woman became the second woman to win the Fields Medal by proving an optimality result for sphere packing: she found the densest packing of identical spheres in 8-dimensional space and proved that no other arrangement can be denser.

Background and earlier position (sphere packing and the meaning of ‘densest’)

Sphere packing problems ask how to place non-overlapping identical spheres so that the resulting arrangement has the highest possible density. In higher-dimensional spaces, visualisation becomes difficult, so “best” is established mainly through a mathematical proof, not just by intuition or examples.

An optimal sphere packing claim typically combines two parts: (1) a construction that achieves a very high density, and (2) a proof that no other arrangement can exceed that density.

What changed now (the caption adds a specific technical optimality statement)