Rest mass photon properties

The modern point of view is that, for every particle that exists, there is a corresponding field with wave properties. In the development of this viewpoint, the particle aspects of electrons and nuclei were evident at the beginning and the field or wave aspects were found later (this was the development of quantum mechanics). In contrast, the wave aspects of the photon were understood first (this was the classical electromagnetic theory of Maxwell) and its particle aspects only discovered later, From this modern viewpoint, the photon is the particle corresponding to the electromagnetic field. It is a particle with zero rest mass and spin one. 

The Spin. How can we reconcile spin s = 1 and Eq = 0 Spin is a constant, identical for all photons of arbitrary energy E. Hence, it is independent of energy and, therefore, it does not depend of the state of motion characterized by go. Also, evidently, spin cannot be a property of a nonexistent rest mass. Therefore, spin is associated with what ... 

If a beam of light can be considered to be a stream of particles (photons), do the photons have mass The answer to this question is no. Photons do not exhibit mass in the same way as classical particles do. Einstein s equations, however, predict that a photon has momentum, which is best thought of as an intrinsic property of the photon that does not depend separately on mass and velocity, unlike the case for a classical particle. In 1922 American physicist Arthur Compton performed experiments involving collisions of X rays with electrons. These experiments showed that photons do exhibit the momentum calculated from Einstein s equation. Also, photons do seem to be affected by gravity, as Einstein postulated in his general theory of relativity. However, it is important to recognize that the photon is in no sense a typical particle. A photon has mass only in a relativistic sense—it has no rest mass. 

There are many examples of mass properties of photons. To the two mentioned above we may add the solar pressure (i.e. photons from the sim which push atoms away from the sun and into space), which has played a significant part in the formation of our planetary system, and measurements showing that photons are attracted by large masses through the gravitational force. Thus we see the evidence for the statement in the beginning that all elementary particles must have relativistic mass, even if the rest mass is zero. 

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