A little "magic" trick with polarized film DO try this at home! I took three pieces of polarized film (which I salvaged from a pair of 3-D glasses). First I put two pieces together (A and B), one rotated at 90 degrees to the other. This effectively blocks out almost all the light. Then, I took a third piece (C), rotated it at 45 degrees, and inserted it BETWEEN the the two pieces, and I could see through all three of them! Here's the weird part - if I insert the third piece (C) IN FRONT OF or BEHIND A and B, no light can get through! Weird or what? The third piece un-polarizes the light. Notice even the camera "sees" the distant building and focuses on it instead of the film. In the first shot, the camera cannot "see" through the film, so it focuses on the film itself. The next step was to use these three pieces of polarized film in what's called a "Quantum Eraser" experiment. I've performed this experiment with excellent results. I'll be posting the results (with pictures) soon.