Why is an electron's changing behaviour upon observation fascinating?

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In summary, the fascination with the double slit experiment in quantum physics stems from the observation of electrons changing their behavior upon measurement, acting like particles instead of waves. This subverts the expectation that the act of observation would only involve an interaction with another particle. However, the experiment can also be conducted with photons, showing that the angle of polarizers can affect the interference pattern without any interaction with the photons. This phenomenon is known as interaction-free measurement and is a key concept in understanding the complexities of quantum physics.
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EvilSapphire
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Due to limit on length, I couldn't properly describe what I wanted to ask on the title. I'm trying to understand the century old fascination physicists have on the double slit experiment. From what I understand, the fascination stems from the act of electrons changing the interference pattern upon observation (acting like particles instead of waves). I can't quite understand however how the expectation would be any different, since an observation would entail some kind of photon interacting with the electron, and since they are of comparable dimensions, it follows very logically such an interaction would change the electron's behaviour in some way. How does this subvert any kind of expectation of the outcome of the experiment? I've decided to learn more about this fascinating subject that is quantum physics which is supposed to explore the structure of reality, however I find myself confused on this most fundamental building block before I go any further. Would love to hear what I'm failing to realize here.
 
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What level do you intend to study QM?

You could try this: to start with:

 
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EvilSapphire said:
I'm trying to understand the century old fascination physicists have on the double slit experiment. From what I understand, the fascination stems from the act of electrons changing the interference pattern upon observation (acting like particles instead of waves). I can't quite understand however how the expectation would be any different, since an observation would entail some kind of photon interacting with the electron, and since they are of comparable dimensions, it follows very logically such an interaction would change the electron's behaviour in some way. How does this subvert any kind of expectation of the outcome of the experiment?

:welcome:

It's true that a cursory examination might lead you to that conclusion. However, there need not be any interaction with another particle to cause the interference pattern to disappear. Further, that would not be the predicted result of such interactions anyway. A better experiment to understand this phenomena is below, with photons instead of electrons.

The general rule is: if you could obtain which slit information - regardless of whether you actually obtain it - there will be no interference.

a. Send a stream of photons through a double slit. There WILL be interference.
b. Place 2 polarizers over the slits, 1 over each slit. Orient them parallel to each other. There WILL be interference as before. However, the intensity will be 1/2 of previous.
c. Now orient one of the polarizers so it is 90 degrees offset from the other - they will now be orthogonal (crossed). There will be NO interference, just the 2 traditional bars when you have an observation. There reason is that the photons have been "marked" to show which slit they went through - even though we do nothing to learn that information.

The only variable that distinguishes b. from c. is the relative angle between the polarizers. If a photon goes through only 1 slit, how is that angle relevant? By your reasoning, the results of b. and c. should be identical (presumably showing interference).

https://sciencedemonstrations.fas.h...-demonstrations/files/single_photon_paper.pdf
 
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1. Why is the concept of an electron's changing behavior upon observation considered fascinating?

The concept of an electron's changing behavior upon observation is considered fascinating because it challenges our understanding of the fundamental building blocks of the universe. It goes against our classical understanding of physics, where objects are expected to behave in a predictable manner. The fact that observing an electron can change its behavior suggests that there is a deeper level of reality that we have yet to fully comprehend.

2. What is the significance of the double-slit experiment in understanding an electron's changing behavior?

The double-slit experiment is significant because it was one of the first experiments that demonstrated the wave-particle duality of electrons. It showed that electrons can behave as both particles and waves, and that their behavior is influenced by the act of observation. This experiment laid the foundation for further research into the strange behavior of electrons and other quantum particles.

3. How does the observer effect play a role in an electron's changing behavior?

The observer effect refers to the idea that the act of observing a system can alter its behavior. In the case of electrons, the act of observing them can change their position or momentum, which is known as the Heisenberg uncertainty principle. This effect is a fundamental aspect of quantum mechanics and is a key factor in understanding an electron's changing behavior upon observation.

4. Can we control an electron's behavior through observation?

While we cannot control an electron's behavior through observation, we can influence it. This is known as the quantum Zeno effect, where frequent observations can prevent an electron from changing its behavior. However, this effect is only temporary, and the electron will eventually resume its natural behavior. Therefore, we cannot fully control an electron's behavior through observation.

5. How does understanding an electron's changing behavior impact our daily lives?

Understanding an electron's changing behavior has led to the development of many technologies that we use in our daily lives, such as transistors, lasers, and computer memory. These technologies rely on the principles of quantum mechanics and would not be possible without our understanding of the strange behavior of electrons. Additionally, the study of quantum mechanics has led to advancements in fields such as medicine, cryptography, and energy production, which have a significant impact on our daily lives.

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