Entangled states before observation.

[Dadface]

Many posters have explained it to you. What I am having difficulty with is you for some reason do not seem to want to accept it.

Its easy - errors and loose language abound in the professional literature and don't always get piked up by referees. That's all there is to it.

Why do you continue to want to pursue it?

Thanks
Bill

I wan't to pursue it because I'm interested in it. Yes posters have explained things and the explanations all seem credible. I have been thankful for the advice given here and haven't, wittingly, rejected any of it. However, the fact remains that there are many others who still refer to concepts such as duality and if the authors referees and journals are all getting it wrong why is it not being more widely challenged. Or if it is being challenged, apart from on this forum, where can I look it up?

The main thing I would like at the moment is for some of the pro duality (camp 2) members to protect their position. I'm getting arguments from one side only and It seems that I'm expected to accept that without question. It's like trying to find the sum of a random series of numbers when half of them are missing.

Please try the following because it might make you better understand my position on this matter:
Do a Google search for Nature.com and when you get to their site search "wave particle duality imaged for the first time". When I tried this earlier 71 hits came up. Look at the titles of the papers on page one. When I did so earlier two titles of particular interest came up:
1. The Duality Principle in the Prescence of Post Selection
2. Wave Particle Duality of Single Surface Plasmon Polaritons
I'm assuming these are published papers and they even referred to duality in their titles. I haven't yet looked at the other pages.

 

[Feeble Wonk]

I'll weigh in here in hopes that you won't feel alone. I am not a physicist either, and likely share many of the same curiosities that you are afflicted by. What I've learned on PF is that the physicists, for the most part, are very rigid in their approach to these matters. The mathematical formalism is all that they are concerned with, and understandably so. Most of them do this for a living, and they want to avoid being caught up in esoteric arguments that are not applicable (and not necessary) to their work. They tend to take the "shut up and calculate" approach.
You are seeing many articles regarding the "wave-particle duality" concept, and you're confused as to why they dispute the validity of the concept. I think what they are saying is that the "words" are misleading because they suggest an ontology that is not supported by modern quantum theory. But, the papers you are citing are likely legitimate works of science, and I suspect that the PF contributors here would be able to explain those findings in mathematical terms that they would be very comfortable with.
Us non-physicists tend to imagine Nature as something tangible... something real that is "out there". So, it's natural for us to be curious about "what" the photons are and how they behave between observations. I suffer from the same tendency. I believe that what they are saying is that neither the image of a wave nor the image of a particle is an accurate representation of what quantum theory says. The only thing the theory describes are predictions about the outcomes of measurements/observations at the time they are made. From their perspective, the theory offers no description of what Nature IS between observations.
That does little to allay our curiosity of course. You will find some authorities here that are more open to this type of speculation, but they are the exception to the rule.

 

[Dadface]

Thank you but I'm not confused as to why the respondents here dispute the validity of the concept of duality etc I'm confused as to why there seem to be so many other physicists who seem to accept the concept of duality. I have been getting some great feed back from the disputers here but nothing from the acceptors. I wonder if there are any acceptors in this forum.

I'm a disputer myself in that with the papers I'm familiar with I see no relevance to the references that have been made about duality and so on. In fact the way I see it the results can be explained perfectly well in terms of classical physics, But I'm talking about a small body of work here and there is a lot more out there to look at.

I want to keep an open mind and try to find out why the acceptors promote the concepts that they do. I wonder why there are so many of them and why the journals accept their work. I take on board the explanations given here but I can't help feeling uneasy about it because there seems to be a huge number of acceptors. Can they all be wrong? If they are all wrong that makes me uneasy because it seems they are not being challenged about it. Why is there not a big debate going on and an insistance from publishers and others that the authors tidy up their work and take more care with the language they use?

But, there still remains a niggling doubt which is that there may be one or even a million acceptors who can justify their acceptance. If so i would like to hear about it. Who knows ,they may have something enlightening to tell.

By the way I have a degree in applied physics but in my career have used only a small part of it. As far as theory goes i consider myself to be an intersted amateur.

 

[zonde]

Thank you but I'm not confused as to why the respondents here dispute the validity of the concept of duality etc I'm confused as to why there seem to be so many other physicists who seem to accept the concept of duality. I have been getting some great feed back from the disputers here but nothing from the acceptors. I wonder if there are any acceptors in this forum.

We can talk about wave-particle duality in two different ways. One is old idea that can be traced back to Bohr about complementarity and the idea that particle and wave nature can not be observed at the same time (sort of implying that sometimes "particles" are particles but sometimes waves but never both at the same time).
In this sense wave-particle duality is not valid but is sometimes used in descriptions of experiments as strawman IMO.

The other sense is that neither concept of "particle" nor "wave" alone fits quantum phenomena.
In this second sense wave-particle duality is valid concept.

So it would be good to provide some context when you say this concept is used. Or at least specify in what sense you want to discuss this concept.

 

[vanhees71]

Well, if you want to be maximally confused, you have to read Bohr or Heisenberg. If you want maximal clarity then read Dirac or Pauli ;-)). The latter have written an early brillant textbook (Dirac, Principles of Quantum Mechanics) and an as brillant review (Pauli, Die allgmeinen Prinzipien der Wellenmechanik; later translated to Enlish as General principles of quantum mechanics). Both are fully valid today about 80 years later.

 

[Dadface]

We can talk about wave-particle duality in two different ways. One is old idea that can be traced back to Bohr about complementarity and the idea that particle and wave nature can not be observed at the same time (sort of implying that sometimes "particles" are particles but sometimes waves but never both at the same time).
In this sense wave-particle duality is not valid but is sometimes used in descriptions of experiments as strawman IMO.

The other sense is that neither concept of "particle" nor "wave" alone fits quantum phenomena.
In this second sense wave-particle duality is valid concept.

So it would be good to provide some context when you say this concept is used. Or at least specify in what sense you want to discuss this concept.

Thank you Zonde. You are right, it would probably have helped to have been more specific and to have put the question into context. Basically at the present time I'm interested in quantum weirdness and I'm trying to find out what it is about certain phenomena for example entanglement that is considered to be weird. In many cases I don't see the phenomena as being weird at all. Well perhaps they are weird but no weirder than phenomena that falls under the banner of classical physics.
Although my opening question was about entanglement the discussion sort of slipped sideways and into duality. That was weird.

 

[Dadface]

Well, if you want to be maximally confused, you have to read Bohr or Heisenberg. If you want maximal clarity then read Dirac or Pauli ;-)). The latter have written an early brillant textbook (Dirac, Principles of Quantum Mechanics) and an as brillant review (Pauli, Die allgmeinen Prinzipien der Wellenmechanik; later translated to Enlish as General principles of quantum mechanics). Both are fully valid today about 80 years later.

Thank you vanhees. I'm often in a state of maximal confusion and I don't think Bohr or Heisenberg will make things worse. The Pauli book in particular looks promising but it costs a lot of beer money. I will shop around.
Thank you for your advice.