Week 230 of John Baez’s *This Week’s Finds in Mathematical Physics* is out. He has returned to one of his favorite subjects (and really, one of everyone’s favorite subjects), Dynkin diagrams. We covered some of the same topics here and here.

*This Week’s Finds in Mathematical Physics* is out. He has returned to one of his favorite subjects (and really, one of everyone’s favorite subjects), Dynkin diagrams. We covered some of the same topics here and here.