Lots of nice content here. I started with the QM section, and it felt like you jumped right in to the particle theory of light. I realized later that of course

Lots of nice content here. I started with the QM section, and it felt like you jumped right in to the particle theory of light. I realized later that of course you have an in depth discussion of the wave theory of light, but I think a bit more explicit connection to that discussion could be helpful. I particularly like coming back to Young’s double slit experiment, which I saw in your discussion of diffraction. To me, the most surprising illustration of the wave/particle duality of light is that single photons passing sequentially through the double slit still form a diffraction pattern. So these particles sort of ‘self-interfere’. One other thought regarding the standing wave demo — maybe you are already familiar with this, but setting up higher order harmonics is a pretty common technique among guitar players (and other stringer instruments), where you pluck a string while touching one of the standing wave nodes. If you’re not familiar with ‘portrait of Tracy’ by Jaco Pistorius, it’s a really cool and unique example of this technique https://m.youtube.com/watch?v=JXOnhzoC-i8 https://m.youtube.com/watch?v=JXOnhzoC-i8