Reading Journal 6 - Behavior

In this section of Six Easy Pieces, Feynman proves the uncertainty principle and the reason sub-atomic particles act as both waves and particles. Feynman first uses a theoretical experiment of bullets (particles) being shot randomly at a wall with two wholes in it. Behind the wall there is a detector that recognizes when bullets make it through. In the experiment there is a chance that the bullet will go through the top hole, P1, and a probability that the bullet will go through the bottom hole, P2. These two probabilities are graphed. Now when a bullet is allowed to go through either hole 1 or hole 2, there is a P12, which is graphed. It is determined that P12 = P1 + P2 due to interference both through probability and the graph. The experiment is then done exactly the same except for with waves. For waves P12 ≠ P1 + P2 because when waves interfere they cancel each other out. Now when this same apparatus is used with an electron gun, it is found that the electrons with the ability to move through both holes independently have an average probability that acts like the particle experiment, but the rate of electrons found is inconsistent. However, when an apparatus is designed that allows us to know which hole an electron goes through there is interference and P12 ≠ P1 + P2, like waves. There is no apparatus that allows us to know which hole and electron goes through without interference because of this electrons, a sub-atomic particle, are considered to act as both waves and particles. When the experiment is done with other sub-atomic particles, results are similar. Because electrons and all sub-atomic particles are unpredictable in both speed and location, we are always uncertain of where these sub-atomic particles will be.