Survey of the Quantum World - 2

In the previous post, I had written about three experiments, namely spraying bullets (several at a time) through the double slit and recording the pattern on the wall, keeping a candle instead of the machine gun and recording the pattern and in the third experiment, shooting a bunch of electrons (in this case we may need a detector instead of the wall) and observing the effects on the detector. Not surprisingly, in the case of the first experiment (with the machine gun bullets), we get the following pattern in which the bullet marks are around the places opposite to the two slits. i.e., we get two distributions on the wall exactly around the places corresponding to the slits.

But, in the case of the second and the third experiment, we get a pattern which is not discrete as above but shades of dark and bright bands like the following figure shows.

One can imagine this kind of dark and bright stripes correspond to the different levels of water that reach the shore on the beach. This is a clear indication that the light and the electrons do not come in discrete packets like the machine gun bullets (otherwise we would be getting two distributions) but they have some sort of a continuous ("wave-like") behavior. Let us now leave the candle light for some time and just concentrate on the electrons. We know that electrons are particles. Numerous experiments show that electron behaves like particles. But then, how do we have dark and bright bands instead of two dark bands like the one we got for the bullets? How do we test the difference between bullets behavior and electrons behavior? That's very simple. Check the behavior bullet by bullet and electron by electron. Its like coding a difficult software. When you don't understand the logic, just break it into modules. Execute it line by line and see where you are going wrong. So, we do the first experiment again this time by just shooting one bullet at a time. Again no surprises here - same pattern with two distributions correspond to the slits. But what about electrons? What will happen if we shoot them one by one and see what pattern it creates when the time progresses? To our surprise, we don't have any surprise - we still get the same dark and white bands, same as what we got when we shoot a bunch of electrons. How can that be possible? This is the beginning of one of the beautiful areas of physics - the Quantum Physics which gives life and meaning to the Hilbert space theory, which otherwise would have lived only to satisfy the whims of the so called "pure mathematicians".

To be continued.