In Pseudo-physics 101, I demonstrated what happens when one tries to “explain” the random behavior of a large number of coins – or any other probabilistic outcome. By “explain” I mean finding a reason, a cause, or a “why.” The “explanation” in Pseudo-physics 101 led to the absurd notion that coins are intelligent!

Pseudo-physics 101 was actually motivated by the “explanation” of quantum mechanical phenomena- which are inherently probabilistic – offered by some people. No one bothers to “explain” the random behavior of coins, but microscopic particles, being studied in physics, are a different story. After all, it is in the very nature of physics to “explain” phenomena.

Photons, the particles of light, behave very strangely when you send them one by one toward a pair of slits carved out on a blocking screen. Many, including some professional physicists, try to “explain” this strange behavior by attributing consciousness to photons. The “consciousness” of photons has a very dangerous ripple effect.

It becomes a “science-based” ammunition for modern crackpot spiritualists to give credence to their nonsense and attract millions of

educatedfollowers.

That is why an accessible elucidation of the quantum theory of photons becomes so essential.

Quantum physics is the most successful theory invented by humankind. It is a mathematical theory whose equations yield a complex (as in “complex numbers”) mathematical function denoted by (pronounced “sigh”), which contains information about the behavior of a physical system. Quantum physics is based on two assumptions about :

- The square of (the absolute value of) is the probability of the behavior of the system. That is why is called the
*probability amplitude*. - If there are two paths for the system to develop, the total of the system is the sum of the s for each path. This is called the
*superposition principle*.

Superposition principle is an all-embracing law that applies not only to quantum phenomena, but also to ordinary situations. It is, for example, responsible for a boat to go northeast when the engine pushes it northward and the water flow carries it eastward.

These two assumptions lead to some strange observations described is the famous *double-slit experiment*. Take a screen that blocks light. Cut two (very very close) identical slits in it. Cover one slit and send photons (particles of light) one at a time toward the two slits. Collect the photons that pass through the slit on a photographic plate. Quantum theory cannot predict the exact location of each photon on the photographic plate, because it is a probabilistic theory. But, as is true in probability, when you send a large number of photons, the prediction of probability becomes more and more realizable, and the shape of the image determinable.

What is the shape of the image formed on the photographic plate after you send a large number of photons? Something like what you see on the right: a single blob. Now cover the first slit and send photons through the second one. The same image is formed on the plate.