http://en.wikipedia.org/wiki/Polarizing_filter
I just read over this and am a little confused. Polarization is the orientation of the electric and magnetic component of a photon relative to a surface, right? So...why would things like parts of the sky polarize light, and how? It seems strange that some things align all of the light and others do not.
As for the polarizing filters...what is their degree of freedom? Do they let all light in besides a certain range, or filter all light out besides a certain range? How many degrees wide is this range? Looking through a single filter, you seem to receive most of the light as depicted in the wikipedia photographs; yet, in my high school physics class, the teacher demonstrated 2 polarizing filters 90 degrees out of alignment completely blocking the light. Do polarizing filters actually alter the polarization of the incoming light, blocking out only the portion that is too much out of alignment to be altered? So, when you align the light along an axis using one filter, and put a filter 90 degrees out of alignment with it, are you essentially forcing the initial light into being at the beyond alteration threshold for the second filter?
Also, can you buy a polarizing filter that retains the same polarization regardless of how it is rotated?
Thx.