Photon Spin: 1 vs 2 - Answers for Alex

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    Photon Spin
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SUMMARY

The discussion centers on the spin characteristics of photons, specifically addressing whether photons can have spin 1 or 2. Participants confirm that photons possess spin 1, as evidenced by their behavior under Lorentz transformations and their description as vector fields. The conversation also distinguishes between photons and hypothetical spin 2 particles, such as gravitons, emphasizing that only spin 1 particles can be classified as photons based on their electromagnetic wave properties.

PREREQUISITES
  • Understanding of Lorentz transformations
  • Familiarity with tensor mathematics, specifically tensor rank
  • Knowledge of electromagnetic wave properties
  • Basic concepts of quantum mechanics and particle physics
NEXT STEPS
  • Research the properties of electromagnetic waves and their relation to spin 1 particles
  • Study the characteristics of gravitons and their theoretical implications in quantum gravity
  • Explore the mathematical framework of tensor fields and their quantization
  • Investigate historical experiments related to photon spin, such as those conducted by Beth in the 1930s
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Physicists, students of quantum mechanics, and anyone interested in the fundamental properties of particles and their interactions in the context of modern physics.

  • #31
The hypothesis is the change caused by interference in the absorption of photons ...
Spin 2?
 
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  • #32
afcarval,

Evidence that photons have spin 1 comes from the nature of electromagnetic waves. EM waves have a linear polarization, and their effects can described by a vector E perpendicular to the wave. Regarding the source, they can be emitted from a dipole antenna. All of these are characteristic of a spin-1 particle.

By contrast, gravitons (assuming they exist) are spin 2 particles. Gravitational waves would have a much different character. Instead of a transverse vector E they would need to be described by a transverse shear tensor. That is, alternate stretching and compression in both directions perpendicular to the wave. Likewise, the source of the wave would need to be quadrupole. Spin 2 waves could not be emitted by a dipole antenna, since they are quadrupole in nature.
 

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