"How does observing photons turn it from a wave into a particle as in the double slit experiment What makes observing change its behavior" - by Marc John Fermee - Quora Question Review

This document contains a review of the answer by Marc John Fermee on the question in Quora: "How does observing photons turn it from a wave into a particle as in the double slit experiment What makes observing change its behavior"
To order to read all the answers select: https://www.quora.com/How-does-observing-photons-turn-it-from-a-wave-into-a-particle-as-in-the-double-slit-experiment-What-makes-observing-change-its-behavior

Contents

Reflection

1. Answer Review

You get into all sorts of trouble if you think like that. A photon is neither a wave nor a particle. Its a quantum of energy in the electromagnetic field.
In short: A photon is a quantum of energy. That is what the Sun emits and that is what you receive when you observe the Sun.
The observation that you are talking about is the measurement system. For a single photon, on absorption, the energy can only be transferred to the measurement system in its entirety. If the measurement system is very spatially small, then all the energy will be transferred to a very small spatial region. This is particle-like. However, notice that it depends on the measurement system being spatially small. In fact, the system could just be a single atom. Does that mean the photon is the size of the atom? Not at all.
If you want to observe interference patterns you need monochromatic light, that means light of the same frquency.
A photon is a quantum of energy in an electromagnetic field mode. In the case of the two slit experiment, the spatial extent of the field mode is actually given by the interference pattern.
That sentence does not explain 'anything'. The question: "what is an interference pattern" is replaced by the question: "what is an electromagnetic field".
So that tells us the spatial extent of the photon (well its transverse profile).
No it does not.
However, our screen relies on absorption of the photon, and our absorbers are extremely small, and only one can absorb the photon. So what do you do? Well you need a theory that describes the observed phenomenon. This is where the Born rule and collapse hypothesis comes in.
Now the question: "what is an interference pattern" is replaced by the question: "what is Born rule" and the "collapse hypothesis".
The Born rule states that the interference pattern is just the probability distribution for observing the photon. The collapse hypothesis corresponds to the local detection of the quantum. What we can say is that the photon was absorbed at that point.
Now the question: "what is an interference pattern" is replaced by the question: "what is a probability distribution".
That question should be answered in detail.
However, the physicality of the collapse is not established by this description of events. That's purely an inference.
Hum....
The fact that at the single photon level, the interference pattern must be viewed as a probability distribution is concerning for some people who are uncomfortable with a fundamental theory being statistical in nature.
My concern is more that you should start to explain using simple language.
This is the indeterminism inherent in quantum theory.
But has a wave actually changed into a particle? We cannot really say that.
Who are the we?
All quantum mechanics does is describe the observed phenomenon using a framework that can be used to predict other phenomena.
In physics in general it is difficult to predict other phenomena.

Page 3

3.

Reflection 1 - Question Review

The question: "How does observing photons turn it from a wave into a particle as in the double slit experiment What makes observing change its behavior" is tricky. The most important issue is that a photon has energy. When a particle hits a surface the photon can be reflected or be absorbed. Absorbed means that the energy of the photon is collected by the surface. This is physical identical as if the photon is observed. The most important point is what physical happens in space before that event.
This question can only be answered by performing many, carefull designed, experiments.
The first experiment performed, starts with a photon source of monochromatic light (all with the same frequency) which is pointed towards a first screen which contain one slit and there after there is a (tiny) photon detector, all in one line. The most important point is that only when the light is turned on the photon detector counts photons.
The second experiment is almost identical as the first. The photon source is exactly the same. The photon detector is not changed. However the slit is closed and a second (closely beside the first) slit is created (or opened). The most important point is that only when the light is turned on the photon detector should count photons. However that is not a must However when there are photons detected i.e. counted, you know that the photons detected can come from two directions: i.e. through slit #1 or slit #2. That is a very important conclusion This depents about which slit is open.
The third experiment is identical. The difference is that both slits are open. In that case the photons detected at the one photon detector, are comming from both slits. In this case you have to place more photons detectors behind the two slits. The result will be that not all the photon detectors show the same count; an interference pattern will result.

The most important point is that this interference pattern is not happening as a result of observing the photons i.e. the photon detectors. The interference pattern already physical exists in the space behind the two slits and before the photon detectors.

If you want to give a comment you can use the following form Comment form
Created: 1 June 2023

Go Back to Quora Question Review
Back to my home page Index