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 he left open the question of whether these distant cousins of the round sphere can have positive curvature. Prof. Yang-Hui He presents work he has done 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 the geometry of the construction and becoming more complex.

Prof. Yang-Hui He is a Fellow at the London Institute. He studied physics at Princeton and did his PhD at MIT. He works on the interface between geometry, number theory and string theory, and is a pioneer in AI-driven mathematical discovery.

Positive exotics
Positive exotics
Positive exotics
Positive exotics
Positive exotics
Positive exotics
Positive exotics
Positive exotics
Positive exotics
Positive exotics
Positive exotics
Positive exotics
Positive exotics
Positive exotics
Positive exotics
Positive exotics