We will follow Chapter 13 in Boas. After introducing some most important equations: heat equation, wave equation, Schroedinger equation, Laplace equation, we will do an exercise on separation of variable.

Questions to ponder:

1. Where does these equation comes from?
2. Why Laplacian is everywhere?
3. Can you write down an equation that describe the heat propagation on a surface?
4. Or maybe wave propagation on a 'curved spacetime' (Minkowski metric tensor), say a Schwrazschild blackhole?