talk:photon#Reference for application of relativistic mass to photon

Under the heading 'annihilation' it would be useful to explain when four or six (or 2n) photons would be produced. The received wisdom seems to invariably prefer 'two', but in 3-dimensional space, six - mutually at rightangles - seems an obvious choice. If there were four they'd need to be in the same plane, but we'd then need to address the question of what their polarization and the angle of that plane should be; (if we were really struggling we'd no doubt dismiss that as 'random'). Also, traditionally photons don't interact in the absence of an electric charge but I understand that exceptionally they can, usually if one is a very high energy ɤ and the other of much lower energy. Assuming that this is the case, it might be helpful to confirm that. It might also be useful to explain when axions can be produced (if such esoteric items exist!). Paul Renshaw (talk) 15:16, 2 November 2023 (UTC)

:If you want to ask questions about a topic, not the article, then the reference desk is a better place. All numbers except 1 are possible in an annihilation reaction. The outcome is random, 2 photons is by far the most common case. Four photons don't have to be in the same plane. There is no reason why 6 should be common, or what would be special about right angles in this context. Photon-photon interactions get more likely with higher photon energies, that applies to both photons (technically: with a higher center of mass energy). --mfb (talk) 19:33, 2 November 2023 (UTC)

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)