[Borodog]

[ QUOTE ]
What I think I know about it comes from a couple of forty year old books. And what I remember reading is so spooky that it gives one pause about whether some supernatural entity could have something to do with it. But every time I mention it the scientists pooh pooh me. Which makes me think that I am thinking things about the experiment, and related exoeriments that aren't true.

So without going into detail, are the following things true?

1. If we watch individual photons as they are going through the slit(s) they make patterns on the screen like they are particles. If we don't watch them, the patterns are those of a wave.

2. If we aren't watching, but we have a movie camera pointed at the slits, the pattern is of particles.

3. If the movie camera has no film the pattern will be waves.

4. IF THE CAMERA HAS FILM AND WE DON'T LOOK AT THE SCREEN UNTIL AFTER WE LOOK AT THE PICTURES, AND ON THE WAY TO THE DRUGSTORE WE FALL AND RUIN THE FILM, WE WILL SEE WAVES ON THE SCREEN. In other words the photons "know" that we will not be able to see them go through the slits, even though our inability to do that is because of an event in the future!

Am I wrong?

[/ QUOTE ]

This is essentially correct, barring the fact that you can't just use a "movie camera". After all, you can see the interference pattern while *looking* at the beam hitting the slits. You have to actually be able to *detect* which slit an individual photon passes through, which requires interacting with it, and localizing it, which is what destroys the interference pattern. But my understanding is that if you do as you say, that is, not observe the screen and wipe out the data of which slit each photon went through, and then observe the screen, you will observe an interference pattern.

Edit: Er, what gump said.