As they entered theater, each took a pair of glasses and put them on.

"See, how they work," the first said, "is the right lens is polarized vertically and--"

"Wait, what do you mean by 'polarized'?" said the second.

"A vertically polarized lets no horizontally polarized light in, and a horizontally polarized lens lets no vertically polarized light in," said the third. "If two perpendicularly polarized lenses are put together, no light is let through."

"So as I was saying, the right lens is polarized vertically, and the left horizontally, or vice versa, such that each eye sees a different picture."

The second had an idea. "So that means if I..." He closed his right eye, and smiled. "Yes, I can only see your right eye."

The fourth and final person (you, of course), sensed something wrong. First, you verified the second's observation. Then, you said...

Though not this comment's only purpose, hints are below.

This was based on a true story, when I noticed that when looking with one eye through polarized 3D movie glasses, I saw the opposite eye that I expected when looking at other people.  These were standard 3D movie glasses, all identical, nothing defective, and I was most certainly not wearing them upside-down.

I eventually figured out why (though I had an advantage, because I could further inspect the glasses).  No advanced optics are taking place here, only what is explained in the problem.

Posted by Tristan on 2006-09-15 00:31:46