3D is all the rage these days, apparently. I've already made my position clear when it comes to what I'm now going to dub faux-3D, because it isn't real, you see. I will repeat it here for posterity. It is bad. And I'm not the only one that thinks so. There are some reports that say that 3D might even be hazardous to your health. Some of my friends, over here at 2d-glasses.com have already taken the initiative and blocked one style of 3D forevermore. Read more for how they did it.
There are a few different principles that faux-3D imagery uses to trick your brain into believing that the images are popping out of the screen in an oh-so-shocking manner. The one that these glasses block use a strange property of photons called polarization. The physics is cool, though that's honestly a given whenever you're discussing anything to do with photons. Tricksy buggers. This is also the most common one that you're going to run into as it's the technology that's already deployed in cinemas nationwide. RealD is one company responsible for many of these systems.
A polarizing filter takes the light wave, which normally vibrates all which ways (denoted by the circular model), and channels the photons so that they are vibrating in a certian linear direction. The 3D glasses are set up so that the left eye would get the photons vibrating horizontally and the right eye would get the ones vibrating vertically. The 3D movies are projected similarly, with separate images projected through polarized filters like so.
Thanks to Wikipedia for the supremely helpful images.
This phenomenon can be played with if you tilt your head side to side while viewing this kind of 3D image. The illusion breaks down and it's quite cool looking. Now, these 2D glasses play off of this same principle except both of the polarizing filters are aligned in the same direction. They completely block one of the projected images. Until now, if you are one of the people who dislikes 3D, either because of headaches and eye-strain issues, or just because you think it's lame, you would just have to skip out on the film your friends were going out to see. Now you can go to see Captain America 3D and act all pretentious and oh-so-much cooler than everyone else because you can block the 3D part without sitting in another room.