A Is wave-matter duality a proven theory?

[koantum]

Summary:: Wave-particle Duality

The observed diffraction patterns in slit experiments are held up as proof of wave-particle duality. But wave theory diffraction (borrowed from optics - Kirchoff's Laws, Fresenel & Fraunhofer diffraction) don't quite fit the experimental results. There is always some tinkering to get theory to match experimental results.

So is there a better explanation of the diffraction patterns observed in slit experiments?

I have heard of a new theory - the field theory of diffraction - that is supposed to offer a fuller explanation.

Can anyone help to explain this new theory.

“Things” like electrons are neither particles nor waves, and this not merely in the sense that they behave neither like traditional particles nor like traditional waves, but in the more radical sense that they lack intrinsic behavior. Classically conceived particles or waves behave the way they do whether or not we observe them. Electrons behave the way they do only if we observe them, and the way they behave depends on the experimental apparatus by means of which we observe them. In short, their behavior is contextual. See this post.

The contextuality of the properties or behaviors of quantum systems, which was stressed by Bohr, is one of the most overlooked features of the quantum theory in contemporary discussions of its meaning. Contextuality means that the properties/behaviors of quantum systems are defined by the experimental conditions under which they are observed, and that they only exist if they are observed. The click of a counter, for instance, does not simply indicate the presence of some object inside the region monitored by the counter. Instead, the counter defines a region, and the click constitutes the presence of something inside it. Without the click, nothing is there, and without the counter, there is no there.

 

[bhobba]

The click of a counter, for instance, does not simply indicate the presence of some object inside the region monitored by the counter. Instead, the counter defines a region, and the click constitutes the presence of something inside it. Without the click, nothing is there, and without the counter, there is no there.

One can look at it that way, but you do not have to. I will leave the post as is, but really it belongs in the interpretation section. What we can say for sure is between observations, what is going on is up for grabs. But speculating on it is something we humans do, rather than what QM says, which is what this subforum is all about.

Thanks
Bill

 

[physika]

I wouldn't dismiss wave-particle duality so quickly.

I agree.

 

[PeroK]

Contextuality means that the properties/behaviors of quantum systems are defined by the experimental conditions under which they are observed, and that they only exist if they are observed.

I just wanted to confirm that the pronoun "they" refers to the properties of quantum systems and not the systems themselves.

That said, there is no reason to tie the existence of something to your classical expectations of it. Classical particles have at all times a well-defined position, say. That does not mean that a quantum particle does not exist (nor that the property of "position" for a quantum particle dos not exist) unless you measure its position.

One could argue that saying that "if something does not behave classically then it doesn't exist" reveals an extraordinary classical bias!

One could perhaps make a stronger case that quantum particles exist; whereas, their classical counterparts do not!

 

[bhobba]

Does the following remark by John von Neumann in 1932 belong to interpretations?

“Indeed experience only makes statements of this type: an observer has made a certain (subjective) observation; and never any like this: a physical quantity has a certain value.”
(“Quantum Theory and Measurement“, edited by John Archibald Wheeler and Wojciech Hubert Zurek, Princeton, New Jersey 1983, page 622):

I do not think the line is hard and fast. I would put it in either. Although not philosophical in and of itself, I think mentors like myself would keep an eye on it to ensure it does not head deeply in that direction.

I would not get too hung up on this sort of stuff. Innocent 'missteps' happen all the time. Detail what you think, and if it is in the wrong place, it will be pointed out with no infringement. Infringements are not issued for innocent mistakes.

Thanks
Bill

 

[gentzen]

But it only acts like a wave in special circumstances such as a free particle. If you want to investigate fundamental things of this sort, such as why quantisation is so common (it does not exist for a free particle, for example), that is a profound question. The following lectures explain it - but it is far from trivial

I admit that those are nice lectures, but how far will I have to watch them before the question "why quantization is so common" will be explained? Actually, in the 3rd lecture at 21:30 Carl Bender talks about "some of his current research" and claims that the potential $x^2(ix)^\epsilon$ leads to discrete positive eigenvalues for all positive real $\epsilon$ despite the fact that it is for example upside down for $\epsilon=2$. He asks: "How could it be that a potential that looks like this has bound states whose energies are up here?" and then goes on: "The answer is: it does! I am not going to explain to you why that is true".

 

[Lord Jestocost]

I do not think the line is hard and fast. I would put it in either. Although not philosophical in and of itself, I think mentors like myself would keep an eye on it to ensure it does not head deeply in that direction.

I would not get too hung up on this sort of stuff. Innocent 'missteps' happen all the time. Detail what you think, and if it is in the wrong place, it will be pointed out with no infringement. Infringements are not issued for innocent mistakes.

Thanks
Bill

Sorry, and thanks for your hint! In case I understand you rightly, I completely agree with you: My comment should have only be released in the "Quantum Interpretations and Foundations" sub-forum. Thus, I have deleted it.

 

[bhobba]

I admit that those are nice lectures, but how far will I have to watch them before the question "why quantization is so common" will be explained? Actually, in the 3rd lecture at 21:30 Carl Bender talks about "some of his current research" and claims that the potential $x^2(ix)^\epsilon$ leads to discrete positive eigenvalues for all positive real $\epsilon$ despite the fact that it is for example upside down for $\epsilon=2$. He asks: "How could it be that a potential that looks like this has bound states whose energies are up here?" and then goes on: "The answer is: it does! I am not going to explain to you why that is true".

It has been a while since I watched them all, but it is there somewhere. It has to do with the wave function reaching around and interfering with itself. I should have mentioned it in my answer. The takeaway is it is not an easy issue - that is all I was trying to get across.

And yes, those lectures are good - worthwhile watching the whole lot.

Thanks
Bill

 

[bhobba]

Sorry, and thanks for your hint! In case I understand you rightly, I completely agree with you: My comment should have only be released in the "Quantum Interpretations and Foundations" sub-forum. Thus, I have deleted it.

There is no need to be sorry. You have done nothing wrong. If you had put it in the wrong place, I would have mentioned it. As I said, it can go in either. But it may lead to replies better in the interpretation subforum - that's all. Thanks for thinking about thread content. It is appreciated.

Thanks
Bill