Talk:Photon#Spin vs. helicity (yet again)

An article describing photons should mention that in addition to Spin Angular Momentum, photons also have Orbital Angular Momentum 50.38.13.172 (talk) 03:35, 19 November 2023 (UTC)

:To make the addition easier, could you provide a reference which discusses this (there might be subtleties)? Best kind of reference would be some established textbook. Jähmefyysikko (talk) 04:20, 19 November 2023 (UTC)

::My copy of Hecht 3rd makes no mention of orbital angular momentum for photons. Johnjbarton (talk) 15:39, 19 November 2023 (UTC)

:So-called orbital angular momentum is a property of extended wave fields or beams of light. Unlike helicity, there is no simple single-particle-like model to think about. Consequently the scientific issues fit poorly in an article about "photons". For example, it is incorrect to say "photons also have orbital angular momentum", its a property of a system.

:Here is an excellent reference: Chen, Jian, Chenhao Wan, and Qiwen Zhan. "Engineering photonic angular momentum with structured light: a review." Advanced Photonics 3.6 (2021): 064001-064001. https://www.spiedigitallibrary.org/journals/advanced-photonics/volume-3/issue-6/064001/Engineering-photonic-angular-momentum-with-structured-light-a-review/10.1117/1.AP.3.6.064001.pdf Johnjbarton (talk) 15:54, 19 November 2023 (UTC)

In my opinion including the full image of the article is inappropriate for an encyclopedia. Johnjbarton (talk) 23:09, 13 May 2025 (UTC)

:Also, there are some discarded ideas about photons. Constant314 (talk) 23:33, 13 May 2025 (UTC)

I noticed in the subsection "Relativistic energy and momentum" that the equation deriving a photon's momentum explicitly defines the variables and describes most the constants, but the Planck constant h is not explicitly labeled. At first I considered that the editors may have believed the inclusion of the description for the reduced Planck constant ħ was good enough, but then I considered how π was also an unreferenced constant used in the equation. A belief that the value of π is common knowledge seems like the justification for not labeling it, and I personally agree. I then considered that the same line of reasoning may extend to the Planck constant. I'm sure π is much more generally familiar than the Planck constant, but where does one draw the line on explicitly listing values of constants in relation to their recognition among readers? The reduced Planck constant is defined which would contradict any guidance to only define variables (and never constants), so I'm left wondering if this is an editorial oversight, or if I'm generally expected to be less dumb. Nom de vileplume (talk) 17:52, 20 June 2025 (UTC)

:I made a small change to address this issue. In general symbols should be explained but I suppose level of the treatment of the topic can result in different choices. Any reader of "energy and momentum" can be, I suppose, familiar with pi. But in the context of Photon, the Planck constant should be called out, rather more than we do here. The so-called derivation ("This derives from the following relativistic relation, with m = 0:") is bogus. The Planck constant is that fundamental constant of nature which derives from the photon. Johnjbarton (talk) 22:24, 20 June 2025 (UTC)

::I made more changes to this section, see if it helps. Johnjbarton (talk) 23:09, 20 June 2025 (UTC)