Angular momentum is a necessary consequence of physics in 3 dimensions. The mathematical structure of angular momentum in quantum mechanics led to spherical harmonics, but also some more mysterious solutions, which play an important role in analyzing the behavior of the physical quantity of "spin". (This lecture is part of a series for a course based on Griffiths' Introduction to Quantum Mechanics. The Full playlist is at http://www.youtube.com/playlist?list=PL65jGfVh1ilueHVVsuCxNXoxrLI3OZAPI.)
