Photon Mass

To the extent every particle exerts a force when it interacts with another physical entity, and to the extent Newton’s Second Law (F=dP/dt) is general, all particles have momentum (P). All particles also have energy (E). 

The momentum of a photon is a function of its wavelength, λ: 

P=h/λ.    (1)

Let us define the photon mass from

m_pc=P

        = h/λ.    (2)

Then

m_p= h/λc.        (3)

In a typical Compton scattering experiment λ=500e-9 meters and hence m_p=4.42e-36 kg. If the scattered electron is initially at rest with a mass of m₀=9.11e-31 kg, then the photon mass prior to scattering is a tiny fraction of the electron’s: m_p/m₀=4.85e-6.  

The energy of a photon is a function of its frequency, ν:

E=hν.    (2)

Or, since

c=λν,        (3)

a photon’s energy can be expressed as

E=hc/λ.    (4)

That is, 

E=m_pc².    (5)

“Conventional wisdom” is that photons have no mass. However, it is gravitomagnetic theory’s position that all tardyons have both charge and mass, whereas all luxons have mass. There are no particles with neither mass nor charge.