Quantum Mechanics: Wave-Particle Duality Explained

In summary, the conversation discusses the concept of wave-particle duality in quantum mechanics and how it applies to matter and radiation. There is a mention of the Copenhagen interpretation and doubts about its validity. The conversation also touches on the de Broglie hypothesis and the role of symmetry in understanding dual nature. It is suggested that a better understanding of quantum mechanics can be gained through more advanced texts and a focus on symmetry.
  • #1
Naman Jain Kota
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Hi, i am doing an introductory course in quantum mechanics (that would be equal to first two chapters in griffith's quantum mechanics).
I have the doubt that what exactly do we consider in quantum mechanics. Let me say like the electron is a particle and when we will observe it will have a defined position, and otherwise it may have been in superposition of various positions according to its probability wave. I guess that's the copenhagen interpratation.

But is that the way we speak of dual nature of matter, like the way we are taught de broglie's hypothesis we say if waves have dual nature particle may also have dual nature with the argument of Symmetry. But in that case I guess and i feel that the way we have dual nature in electromagnetic radiation, we must have dual nature of electron same way.
The wave associated with matter is only a probability wave.
That wasnt the way i thought about dual nature, it was somewhat like electron is a well particle at sometime and a wave at some time like photons or other way i.e. like photons also have some probability associated in form of wave and things like collapsing etc.
And more general i guess we must have fundamental equation applying both for radiation and matter, even if photons are mass less.

Please point out conceptual mistakes! and i know interpretation of quantum mechanics is a big job not so at basic level. Does quantum field theory have provide some solution to this wave particle problem.
 
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  • #2
Wave particle duality does not exist.
The deBroglie stuff is of historical importance only.

The "wave" associated with a particle is a complex probability amplitude - the probability density function is this wave multiplied by it's complex conjugate. And no, that is not how you'd normally think about things: it's called "counter-intuitive" for a reason.
Please see: http://vega.org.uk/video/subseries/8
 
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  • #3
Naman Jain Kota said:
Hi, i am doing an introductory course in quantum mechanics (that would be equal to first two chapters in griffith's quantum mechanics).
I have the doubt that what exactly do we consider in quantum mechanics. Let me say like the electron is a particle and when we will observe it will have a defined position, and otherwise it may have been in superposition of various positions according to its probability wave. I guess that's the copenhagen interpratation.

But is that the way we speak of dual nature of matter, like the way we are taught de broglie's hypothesis we say if waves have dual nature particle may also have dual nature with the argument of Symmetry. But in that case I guess and i feel that the way we have dual nature in electromagnetic radiation, we must have dual nature of electron same way.
The wave associated with matter is only a probability wave.
That wasnt the way i thought about dual nature, it was somewhat like electron is a well particle at sometime and a wave at some time like photons or other way i.e. like photons also have some probability associated in form of wave and things like collapsing etc.
And more general i guess we must have fundamental equation applying both for radiation and matter, even if photons are mass less.

Please point out conceptual mistakes! and i know interpretation of quantum mechanics is a big job not so at basic level. Does quantum field theory have provide some solution to this wave particle problem.

If you were expecting Griffiths to explain the wave-particle duality, you will be disappointed. He mentions in the Afterword (Chapter 12, page 420, of the 2nd Edition) as a historical footnote.
 
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  • #4
Here is a much better view of exactly what QM is about:
http://www.scottaaronson.com/democritus/lec9.html

If your introductory course teacher wants to argue with an MIT professor - good luck.

Take my word fir it its a much better view than the semi-historical half truths promulgated in popularisation's and some introductory courses.

My view is the following is THE introductory textbook to get after a first course in general physics such as IB Physics HL or similar
https://www.amazon.com/dp/3319192000/?tag=pfamazon01-20

Symmetry is the real deal rock bottom essence in physics but unfortunately usually only taught later at graduate school. The above corrects that oversight that has been around far far too long.

Then you can read Ballentine - QM and Landau Mechanics with ease and have a very though grasp of physics well and truly ready for really hard stuff like by Peskin and Schroeder althoigh I would do the following first:
https://www.amazon.com/dp/019969933X/?tag=pfamazon01-20

Thanks
Bill
 
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  • #5
PeroK said:
If you were expecting Griffiths to explain the wave-particle duality, you will be disappointed. He mentions in the Afterword (Chapter 12, page 420, of the 2nd Edition) as a historical footnote.
Well, finally there's something good about Griffiths's QM book ;-)).
 

1. What is wave-particle duality in quantum mechanics?

Wave-particle duality is the concept that matter can exhibit both wave-like and particle-like behaviors. This means that at the quantum level, particles such as electrons and photons can behave like waves, with properties like wavelength and interference, and also like particles, with properties like position and momentum.

2. How does wave-particle duality challenge classical physics?

Classical physics describes the behavior of macroscopic objects, while quantum mechanics governs the behavior of particles at the subatomic level. In classical physics, an object can only have one measurable property at a time, but in quantum mechanics, particles can have multiple properties simultaneously, which is known as superposition. This challenges the classical idea of a definite, predictable reality.

3. What experiments demonstrate wave-particle duality?

The double-slit experiment is a classic demonstration of wave-particle duality. In this experiment, a beam of particles, such as electrons or photons, is directed at a barrier with two narrow slits. The particles behave like waves and create an interference pattern on a screen behind the barrier, even when sent through one at a time. Another experiment is the photoelectric effect, which demonstrates the particle-like behavior of light.

4. How does the observer affect the behavior of particles in wave-particle duality?

The observer effect refers to the idea that the act of measurement can affect the behavior of particles. In the double-slit experiment, when the particles are observed, they behave like particles and pass through only one of the slits, instead of creating an interference pattern. This suggests that the act of measurement collapses the wave-like behavior of the particles into a definite position.

5. How does understanding wave-particle duality impact technology?

Understanding wave-particle duality has led to advancements in technology, such as the development of transistors and lasers. It has also paved the way for quantum computing, which utilizes the principles of superposition and entanglement to process information at a much faster rate than classical computers. Additionally, concepts like quantum entanglement have potential applications in secure communication and teleportation.

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