Undergrad Interpretation of photons having zero spin

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Photons are established to have a spin of 1, contrary to the initial claim of zero spin. This distinction is crucial as it relates to their properties in quantum mechanics, where the spin operator must reflect observable characteristics. The discussion also touches on the mathematical representation of spin states, emphasizing that a null operator would indicate a lack of observable spin, which is not the case for photons. The confusion between spin values highlights the importance of accurate interpretations in quantum physics. Understanding these properties is essential for deeper insights into particle behavior and interactions.
Tio Barnabe
What is the interpretation of the fact that photons have spin zero? Does it has do to with the fact that their proper time variation is zero?

Or let's go a bit deeper into the math. If it's possible to write down an eigenvalue equation for photons as it is possible for electrons, then we should have something like

S ketψ = λ ketψ, where ψ is a photon general state, S is the spin operator and λ the spin eigenvalue.

For this to be zero, I think one way is if the operator S is a null operator. But operators in QM are the mathematical translation of observables. So a null operator corresponding to a given observable means that that observable is not actually observed, correct? We would conclude that the photon has no observable spin.

This doesn't answer my initial question if it's related with the proper time of the photon though.
 
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Tio Barnabe said:
What is the interpretation of the fact that photons have spin zero?

Where are you getting that from? Normally, I would say that photons have spin one.
 
Tio Barnabe said:
What is the interpretation of the fact that photons have spin zero?
Photon has spin 1 and Higgs boson has spin 0. (Source: Wikipedia)
You may find this thread on spin 0 particle helpful.
 
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stevendaryl said:
Where are you getting that from? Normally, I would say that photons have spin one.
Mistake. Indeed photons have spin 1.

arpon said:
You may find this thread on spin 0 particle helpful.
Indeed very helpful. I don't know how I could have forgotten it. I have read about it in the great Sakurai's book.
 
These papers by Pegg et al. (doi: 10.1016/j.shpsb.2008.02.003 [section 4]; https://www.researchgate.net/publication/230928426_Retrodiction_in_quantum_optics [section 3.2]) seem to show that photon Bell correlations can be inferred using quantum theory in a manner that is compatible with locality by performing quantum retrodiction (i.e. inferring information about the past: e.g. https://doi.org/10.3390/sym13040586; more papers at end) where they evolve backward from Alice's measured outcome...

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