Talk:Spin quantum number

Electron spin analogy
A spinning zero diameter electron has zero angular momentum, because no part of the electron’s mass extends beyond a radius of zero. The angular momentum L of a particle about a given origin is defined as:


 * $$\mathbf{L}=\mathbf{r}\times\mathbf{p}$$

where r is the position vector of the particle relative to the origin, p is the linear momentum of the particle, and × denotes the cross product.

Including electron ‘spin quantum number’ within the Spin (physics) article, w/o identifying the conflict between the zero diameter and non-zero angular momentum gives the impression that a spinning electron with zero diameter indeed has momentum, and the impression that (zero diameter) electron spin is the cause of magnetic moment.

“… an angular momentum and a magnetic moment could indeed arise from a spinning sphere of charge, but this classical picture cannot fit the size or quantized nature of the electron spin. The property called electron spin must be considered to be a quantum concept without detailed classical analogy. ” http://hyperphysics.phy-astr.gsu.edu/hbase/spin.html

“The term "electron spin" is not to be taken literally in the classical sense as a description of the origin of the magnetic moment described above. To be sure, a spinning sphere of charge can produce a magnetic moment, but the magnitude of the magnetic moment obtained above cannot be reasonably modeled by considering the electron as a spinning sphere. High energy scattering from electrons shows no "size" of the electron down to a resolution of about 10-3fermis, and at that size a preposterously high spin rate of some 1032 radian/s would be required to match the observed angular momentum.” http://hyperphysics.phy-astr.gsu.edu/hbase/spin.html    Vze2wgsm1 (talk) 23:28, 16 February 2011 (UTC)

What's the spin quantum number?
The start of the article says $$m_s$$ is the spin quantum number. Later at some point it calls $$s$$ the spin quantum number. They are different things. Is there a standard definition of "spin quantum number", or do experts freely call both of these things the "spin quantum number"? If there's a standard definition, let's only call one of $$m_s$$ and $$s$$ the spin quantum number, not both. If there's not a standard definition, we should warn the reader. John Baez (talk) 19:49, 1 December 2021 (UTC)


 * I attempted to answer this question in the intro in June-July 2021, especially by adding the third paragraph: "At an elementary level, $m_{s}$ is described as the spin quantum number, and $s$ is not mentioned since its value 1/2 is a fixed property of the electron. At a more advanced level where quantum mechanical operators are introduced, $s$ is referred to as the spin quantum number, and $m_{s}$ is described as the spin magnetic quantum number or as the z-component of spin $s_{z}$." (plus references). This warns the reader that there are indeed two definitions depending on the level of the textbook. Dirac66 (talk) 00:54, 2 December 2021 (UTC)

Too technical?
@‎Lingonberry 666 you added the Template:Technical but you did not open a corresponding Talk to explain why. What are your suggestions? Johnjbarton (talk) 16:26, 18 February 2024 (UTC)


 * Sorry, I'm new to Wikipedia and didn't know I had to. Anyways, I think it jumps into too much technical detail too soon. My suggestions are that more of the basic concepts should be explicitly defined and briefly explained as the article introduces spin quantum numbers at the beginning of the article. I think that since most of this article's readers are probably students, the article would attract more readers if it explained spin quantum numbers one step at a time. Lingonberry 666 (talk) 18:42, 18 February 2024 (UTC)
 * Ok thank you. I will take try. Johnjbarton (talk) 19:02, 18 February 2024 (UTC)

Most of this material belongs in Spin (physics)
The majority of the material in this article is about the physical phenomenon, not about the quantum number. Johnjbarton (talk) 21:58, 18 February 2024 (UTC)