Positive exotics
2 PM, 16 Oct 2026
Yang-Hui He explains how to find positively sectionally-curved metrics on all 28 smooth seven-spheres, answering a question from the 1950s.
In 1956, John Milnor discovered exotic seven-spheres but left open the question of whether these distant cousins of the round sphere can have positive curvature. Prof. Yang-Hui He presents work with Ziran Liu and Fields Medallist Shing-Tung Yau, assisted by GPT Astra, constructing positive metrics on all seven-spheres. The talk begins at undergraduate level before turning to more advanced details of the construction.
Prof. Yang-Hui He is a Fellow at the London Institute. He studied physics at Princeton, then did the mathematics tripos at Cambridge and a PhD at MIT. He works on the interface between geometry, number theory and string theory, and is a pioneer in AI-driven mathematical discovery.















