Chapter 2 – Wave functions and uncertainty

Wavefunctions and interference

Probability distributions for where a particle is can be determined from its wave function. This discussion will loosely consider wave functions and probability distributions as equivalent. It is not strictly correct but is sufficient for this introduction.

The concept of probability distributions applies to the electrons moving through the double slit experiment. Just as we could assign probabilities to where our traveling friend is, we can also assign them to electrons. The blue arcs in this diagram show where the electron could be after times 1, 2, 3 and 4.

It gets interesting looking at the probabilities of the electrons that make it through one of the slits. Just like our friend who has different possible routes, the electron has different possible paths so the probability distributions split at times 5, 6 and 7:

By the time the electron reaches the screen, the overlapping probability distributions give the regions of higher probabilities that cause the interference pattern.