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Can someone explain what W.E. Lamb means in his paper, Anti-Photon, when he speaks of photons as being a terrible and poor way to describe the light? The abstract reads,

It should be apparent from the title of this article that the author does not like the use of the word "photon", which dates from 1926. In his view, there is no such thing as a photon. Only a comedy of errors and historical accidents led to its popularity among physicists and optical scientists. I admit that the word is short and convenient. Its use is also habit forming. Similarly, one might find it convenient to speak of the "aether" or "vacuum" to stand for empty space, even if no such thing existed. There are very good substitute words for "photon", (e.g., "radiation" or "light"), and for "photonics" (e.g., "optics" or "quantum optics"). Similar objections are possible to use of the word "phonon", which dates from 1932. Objects like electrons, neutrinos of finite rest mass, or helium atoms can, under suitable conditions, be considered to be particles, since their theories then have viable non-relativistic and non-quantum limits. This paper outlines the main features of the quantum theory of radiation and indicates how they can be used to treat problems in quantum optics.

Citation: Lamb, "Anti-Photon", Appl. Phys. B 60, 77-84 (1995); pdf link

I understand his assertion that light does not consist of a "particle" in the modern sense of the word, but my question is why does he feel this is a bad description? The paper goes on to explain basic ideas of QED, but I do not see from his paper points that support his argument.

If I seem to be missing the point he makes could someone please point it out to me? Also, he makes the assertion: " Read the Fermi article, or forever go on thinking that photons exist", could someone link me to the specific paper: (16. E. Fermi, L. Marshall: Phys. Rev. 72, 1139 (1947)) that he is talking about? (Or at least point out to me where I could find it?)

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    $\begingroup$ I think this is a reasonable question (+1), but it might be helpful to give a key quote or two from the paper in the question text here so one can get some sense of what the question is before clicking the link. $\endgroup$
    – Rococo
    Sep 26, 2016 at 0:04
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    $\begingroup$ In this paper he discusses the radiation field and find these normal modes (like harmonic osillators) with discrete energies. However, he states that these normal model are "not localized in any meaningfull manner, and they do not behave at all like particles". Counts in photo detectors can just be explained by quantum description of fields. I sense he attaches the conditions that something is called a particle if it's localized in space for given short time which is not the case. $\endgroup$
    – Jan Bos
    Sep 26, 2016 at 0:27
  • $\begingroup$ @JanBos Thanks, I guess I wasnt able to pick up on that. $\endgroup$
    – Haru Fujimura
    Sep 26, 2016 at 12:22
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    $\begingroup$ @march Could not agree more. Besides describing his objections to calling these EM field quanta particles he gives one of the best short histories of physics I've seen. Clearly written by a master in the field. $\endgroup$
    – Jan Bos
    Sep 27, 2016 at 2:58

2 Answers 2

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This paper is about the way we communicate about the quantum nature of light, both in research literature and in education. Ultimately, our fundamental physical theories are formulated in terms of fairly rigorous mathematics; when studying the quantum nature of light, this will be the mathematics of QED. Some concepts like operator and Lagrangian are central to the theory, and map directly to the mathematical description. Other concepts like laser beam and atom do not map precisely to the mathematical description, but are practically useful for:

  1. Applying the theory to phenomena seen in the lab.
  2. Linking the theory to other theories to compare predictions
  3. Educational purposes

In this article, Lamb argues that the concept of a photon is neither fundamental to the mathematical description, nor a useful practical abstraction. These are some of the arguments he uses:

  • Popular science texts often misuse the term 'photon'

In a 1969 Scientific American collection "Lasers and Light", G. Feinberg [20] stated that "What the laser does is to produce vast numbers of particles of exactly the same energy and wavelength. With no other stable particle but the photon is such a feat possible. The laser beam's remarkable macroscopic properties arise that its constituent particles are precisely identical. Whether the laser could have been invented without quantum mechanics is an interesting question"

  • Some textbooks on laser physics barely mention the photon

M. Sargent, M.O. Scully and W.E. Lamb [25] (first edition 1974; third edition, 1976; "Laser Theory", very few photons)

  • Many physical phenomena are better described in terms of modes and quantum harmonic oscillators (sections 4,5,6 in the paper)

Note: I am just summarizing the arguments expressed from the paper; personally I don't find either of them very convincing

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  • $\begingroup$ His arguments are actually very convincing. To explain the photoelectric effect there is no need to introduce the photon as a particle. Actually for the photoelectric effect in a gas the particle explanation does not even work. For the double slit experiments the photon as a particle just creates confusion. QFT (Fermi's golden rule) can explain it nicely as how photo detectors interact with the field. Basically the photon as a particle is pretty much debunked. $\endgroup$
    – Jan Bos
    Oct 2, 2016 at 4:22
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    $\begingroup$ @JanBos but besides having zero mass and charge, it doesn't differ much from e.g. alpha-particle. So is $^4\mathrm{He}^{++}$ also debunked as a particle? $\endgroup$
    – Ruslan
    Oct 3, 2016 at 10:11
  • $\begingroup$ @Ruslan If you look them on very small scales and high energies they can only be described by quantized waves (e.g. you need the gluon fields etc to describe their nucleons). However, in contrast to the photon on macroscopic scales you could talk about them as localized bodies that move around at finite speeds and the particle notion makes more sense. $\endgroup$
    – Jan Bos
    Oct 4, 2016 at 1:11
  • $\begingroup$ @JanBos I dont find it too convicing. His reasoning is we need to find the normal modes first. So what if I put a lense/mirror (emphasis on put) in the 'trajectory' of a photon, it doesnt even make sense in his description of how to deal with the field. Also I believe without the word photon nobody would have come up with QC (wether this is a good or bad thing) $\endgroup$
    – lalala
    Jul 9, 2018 at 18:50
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Note an alpha particle (and an electron) can be accelerated, they can exist with or without motion. A photon is the smallest quantum of light that will interact with matter ; a photon is electro magnetic radiation with energy of one Plank constant times frequency. A photon cannot be accelerated, it does not exist without motion, it does not have all the properties of a particle.

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