Legitimacy of Particle-Wave Duality

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In summary, the conversation discusses the concept of particle-wave duality in the context of teaching Quantum Mechanics. Some commenters question the validity and usefulness of this concept, while others argue that it is still a useful tool in teaching and understanding physics. The conversation also touches on the limitations of this concept and how it has been replaced by modern quantum theory. Overall, there is debate about the relevance and accuracy of particle-wave duality in the field of physics.
  • #1
Zacarias Nason
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I'm asking this question not because of my own misgivings but someone else on this forum some time ago made a comment in a different context which, when talking about teaching Quantum Mechanics, was something like, "Do they still teach things like the particle-wave duality, too?" as a criticism.

I simply don't know enough about this other than a rudimentary understanding and vague relation to the De Broglie wavelength and the Photoelectric effect, and haven't run into it as a standalone topic in QM. I'd like others' thoughts on this, because as far as I am aware with my pretty limited knowledge, particle-wave duality isn't some ridiculous, fundamentally flawed concept as the poster made it out to be.

Even if it was, I still think it was a little absurd that the above was said when we still teach things like the plum pudding model as a temporary stepping stone to an electron cloud model, or we still teach the octet rule in Chemistry despite it only being valid for very limited cases; particle-wave duality could, carefully applied, be a pedagogical tool, regardless of if it is exactly true.

What is (or is not) wrong with particle-wave duality?
 
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  • #2
In my view nothing. But it seems to irritate threoreticians :smile: . I'm happy with the idea that a physics subject can be dealt with employing a certain paradigm, but that you most likely will have a deeper layer where things are (quite) a bit different and corrections for extreme situations may follow.
 
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  • #3
Zacarias Nason said:
I'm asking this question not because of my own misgivings but someone else on this forum some time ago made a comment in a different context which, when talking about teaching Quantum Mechanics, was something like, "Do they still teach things like the particle-wave duality, too?" as a criticism.

You are right about the questions being raised about "correctness" of the older theories working in development path of physics-evolution of perspectives.there are other examples-say Bohr's atomic model etc.

At each level the working of the 'model' as wave or at some other time as particle was substantiated by experimental observation but later developments in quantum theory did not need a description as wave or particle.
Its like working with a model and it gives you results -showing the correctness of the "model" - but one must not substitute his "model" for the actual thing.
A glaring model description is force of gravity -which we treated as force existing between masses- but now we see the effect of gravity as a curvature of "space time' in the GTR.
unless one goes tothe description of particles and their creation/interaction in terms of Quantum Field theory-the model mechanism will prevail.
 
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  • #4
We had a thread about relativistic mass, a pretty advanced subject in my view, where I got the impression the theoreticians really wanted it rooted out.

Nugatory said:
we have a FAQ on why relativistic mass is seldom used - look for a link to it in the sticky thread at the top of this forum

[edit] found it:

arupel said:
I am not sure exactly what E = mc^2 means.
And I have high esteem for Oro, but here we differ. (See #4, #8,#11 -- he has good points)
 
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  • #5
You could consider "wave-particle duality" in light of the Heisenberg Uncertainty Principle. If you do that, you will see that "wave" and "particle" are essentially the extreme points you occupy on what is actually a continuous spectrum. If you know position accurately, it acts as a particle. If you know momentum accurately, it acts as a wave. But you can also get behavior which is (very loosely speaking) half-wave and half-particle too.

So there is nothing particularly special about the duality in this light, as it maps to another quantum principle. But it is often convenient in terms of a mental model.
 
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  • #6
I won't speak for the other mentors and science advisors, but I tend to judge imperfect models such as wave-particle duality by the amount of grief that they cause me: The more time I have to waste spend trying to unconfuse people who have been confused by a model (usually by not understanding its limitations), the more critical of it I am. The popular presentation of "wave-particle duality" is a major offender.
 
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  • #7
BvU said:
In my view nothing. But it seems to irritate threoreticians :smile: . I'm happy with the idea that a physics subject can be dealt with employing a certain paradigm, but that you most likely will have a deeper layer where things are (quite) a bit different and corrections for extreme situations may follow.
Well, what's wrong with it is that it is an long out-dated concept. It was substituted by modern quantum theory in 1925.
 
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  • #8
DrChinese said:
You could consider "wave-particle duality" in light of the Heisenberg Uncertainty Principle. If you do that, you will see that "wave" and "particle" are essentially the extreme points you occupy on what is actually a continuous spectrum. If you know position accurately, it acts as a particle. If you know momentum accurately, it acts as a wave. But you can also get behavior which is (very loosely speaking) half-wave and half-particle too.
This is a really, really cool concept. I've never seen it like that.
 

1. What is the concept of particle-wave duality?

Particle-wave duality is the idea that all particles, such as subatomic particles like electrons, can exhibit both particle-like and wave-like behavior. This means that these particles can act as discrete units of matter with a defined position and momentum, but can also behave like a wave with properties such as diffraction and interference.

2. How was the idea of particle-wave duality first discovered?

The concept of particle-wave duality was first introduced by the French physicist Louis de Broglie in 1924. He proposed that if light can behave as both a wave and a particle, then perhaps matter particles could also have wave-like properties. This idea was later confirmed through experiments, such as the double-slit experiment, which showed the wave-like behavior of electrons.

3. What evidence supports the legitimacy of particle-wave duality?

There have been numerous experiments that support the idea of particle-wave duality. These include the double-slit experiment, the diffraction of electrons through a crystal, and the observation of interference patterns in electron waves. Additionally, the principles of quantum mechanics, which successfully explain the behavior of particles, are based on the concept of duality.

4. Can all particles exhibit particle-wave duality?

Yes, all particles can exhibit particle-wave duality. However, the effects of duality are more noticeable in smaller particles, such as subatomic particles, because their wavelengths are comparable to their size. Larger particles, such as macroscopic objects, have wavelengths that are too small to exhibit significant wave-like behavior.

5. What are the implications of particle-wave duality?

The concept of particle-wave duality has significant implications for our understanding of the fundamental nature of matter. It challenges our traditional understanding of particles as discrete, solid objects and suggests a more complex and dynamic nature. This concept is also crucial in modern technologies, such as quantum computing and electron microscopy, which rely on the wave-like behavior of particles.

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