The famed Poincaré Conjecture - the only Millennium Problem cracked thus far. More links & stuff in full description below ↓↓↓ Ricci Flow (used to solve the problem): https://www.youtube.com/watch?v=hwOCqA9Xw6A Riemann Hypothesis: https://www.youtube.com/watch?v=d6c6uIyieoo Extra interview footage with Jim Isenberg: https://www.youtube.com/watch?v=7eJleW0JcKg Grigori Perelman's paper: http://bit.ly/perelmanpaper Discussed here by Katie Steckles and James Isenberg. Support us on Patreon: http://www.patreon.com/numberphile NUMBERPHILE Website: http://www.numberphile.com/ Numberphile on Facebook: http://www.facebook.com/numberphile Numberphile tweets: https://twitter.com/numberphile Subscribe: http://bit.ly/Numberphile_Sub Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile Videos by Brady Haran Brady's videos subreddit: http://www.reddit.com/r/BradyHaran/ Brady's latest videos across all channels: http://www.bradyharanblog.com/ Sign up for (occasional) emails: http://eepurl.com/YdjL9 Numberphile T-Shirts: null Other merchandise: https://store.dftba.com/collections/numberphile