Matt tackles some of the big misconceptions about light, which stem from how light and polarization are presented.
What’s good about the picture is that it conveys the idea of what it means for a polarizer to select a polarization. What’s bad about it is that the “picket fence” metaphor doesn’t really have anything to do with the actual physics of light polarization. Instead it furthers the exact misconception we talked about in my earlier post – that the crests and troughs of the wave have a physical up-and-down extent in space. They do not. The ups and downs represent the strength and direction of the electric field at that point, that’s all.
I remember a professor bringing this up in college. It’s easy for me to understand why the wrong picture is accepted — it seems plausible, and there’s not much reason to question it at the level it’s presented.