Diffraction and Ghost Electrons (Science)

When you usually think of a particle you may think of a solid object; a definite thing which you could measure the whereabouts of if you wanted if you knew enough information about the particle.

Unfortunately this classical physics view of the world is no longer thought of as “correct”. (I say unfortunately as it makes things more awkward; however I like a challenge so I would say it was more interesting)

To give you an extremely brief idea about what I’m saying I will postulate an example:

Say we take a beam of electrons and put it through a single slit diffraction experiment like so:

We get a diffraction pattern like this

We get this pattern because of electron wave-particle duality but that’s not important for the moment.

Lets make the experiment a little more complex lets say there are 2 slits after the single slit diffraction experiment (so a double slit diffraction experiment) A and B. Now when we fire the electron beam the electron can either go through A or B to hit the screen.

Now as we should we get an interference pattern similar to a wave when we conduct the experiment.

Here’s where it gets weird.

Imagine that there’s a detector at A and B. These detectors ascertain whether or not the electron passes through it or not.

When this is done in experiment the final interference pattern changes; we only get single slit diffraction interference pattern.

Why? We must assume that by measuring where the electron is we have made it so that it has to travel through 1 path; and the rest of the time it actually travels through A and B as 2 “Ghost” electrons. It travels every available path to the screen until it is detected and then all the ghost electrons “collapse” into one “real” electron.

Believe it or not; one single electron fired in the experiment will actually diffract with itself.

Happy Easter :D

Andrew