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jedishrfu

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https://phys.org/news/2015-03-particle.html

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jedishrfu

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https://phys.org/news/2015-03-particle.html

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The original article:

https://www.nature.com/articles/ncomms7407

https://www.nature.com/articles/ncomms7407

- #3

tech99

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What's indeed shown by this experiment is that plasmon modes of the em. field are quantized. That's all. There's no particle picture for photons proven ever. Photons cannot even by localized, because they do not admit the definition of a proper position operator to begin with. This is true even for free photons, let alone for cavity photons or plasmon modes, as investigated here. The Nature article is pretty clear on what's measured (and it's open access!).

- #5

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What is the ##R_0## of belief in wave-particle duality? Can it be properly treated or vaccinated against?Planck once said that old-fashioned theories in physics die out by people believing in them passing away.

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Of course, I surveyed the existing (German) literature on "Quantum Mechanics for teachers students", and I was shocked that the books provided utterly wrong pictures about quantum theory. Particularly all start with photons, which is the most complicated real-world quantum you can discuss. Allready free photons cannot be adequately discussed without a quite thorough analysis of the Poincare group, and unfortunately there's no time to teach this in this three-semester theory course. Nevertheless, on a qualitative level, one can describe all the modern single-photon experiments correctly without "drawing" the wrong picture of photons as "pointlike particles". One of the textbooks (there's even an English translation: it's Pade, Quantum Mechanics for Pedestrians, Springer 2014, 2 vols) which in principle is a very nice book, discussing modern applications of quantum theory on a level, which is well suited for this target group of students, using discrete-observable examples like spin and polarization states particles or photons etc., discussing Bell inequalities, entanglement, and all that. Hoever, I cannot recommend this book without a bad consciousness, because it's all wrong in its qualitative explanations. Rather than being careful to explain photons in a way of what's really observed and what comes out from the proper analysis of the Poincare group (which of course you cannot give to this target group; it's usually not even fully treated in BSc/MS lectures on QED, because you'd need an entire semester for the mathematics of the Poincare group rather than discussing real physics problems). On this qualitative level you can however still explain it correctly by sticking to what's observed and then just telling the students what comes out of the proper treatment within modern QED.

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Perhaps it's part of "selling" the subject. Like the Scottish Tourist Board promoting the Loch Ness Monster!

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What I'm really angry about is that new textbooks are written, particularly with an emphasis in didacticts in the sense to simplify the theory such that physics-minor students can easily understand the essence, which are plain wrong in the picture they convey about QT. It's the more sad, because that's not even necessary to make the subject simple enough!

E.g. you can explain the Mach-Zehnder experiment with single photons without ever relying on a naive and plain wrong particle picture of photons. Even emphasizing the localizability of photons which is impossible from first principles mathematically in such books is a sin!

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@vanhees71, how would you classify Weinberg's books? They are good in qualitative explanations?

- #10

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- #11

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which books exactly?

TheseI know, Gravitation and Cosmology, 3 vols. Quantum Theory of Fields, Cosmology, and Lectures on Quantum Mechanics

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