Today we had a special treat: a visit from Josh Sakon, a biochemistry professor at the U of A, a guy that works with Fourier transform on a daily basis.  

We first played with lasers and saw that shooting a laser through small holes yields small dots. Surprise surprise. Next, we shot the lasers through tiny little holes, and got... large dots! What is going on? This was our first encounter with diffraction.

Josh brought a model that shows how diffraction happens in one simple case, and demonstrates Bragg's Law. We then build our own "models", using pegs and strings, to understand how interference explains these phenomena. The picture of interfering waves was shown beautifully on the model Josh brought.

All these things explain why tiny holes yield big spots, a phenomenon called reciprocity. That was a lot of stuff, and we will review these things when we meet next time.

See here for details about the summer camp we discussed.