Entertaining and informative science video explaining the quantum physics "double slit" experiment. It is a short clip from the extended directors cut of "What the *Bleep* Do We Know", which was a movie that tried to present science as religion (instead of the Intelligent Design approach of presenting religion as science).
For the most part this clip stays true to science. Near the end, when they are talking about a "mysterious observer" and the electron "knowing it is being watched", I can see where science has taken a back seat to crafting an interesting story. In reality, since we can't just set up a video camera to observe these incredibly small particles/waves, the act of observing is not as passive as they describe. Reminds me of that old physics joke:
Heisenberg was driving down the Autobahn whereupon he was pulled over by a policeman. The policeman asked, "Do you know how fast you were going back there?" Heisenberg replied, "No, but I know where I am."
For those of you who don't get it google Heisenberg Uncertainty Principle. Simply put:
A consequence of the HUP is that if an object's position x is defined precisely then the momentum of the object is completely unknowable, and vice versa.