Van Snyder writes: >Radation has mass, as can be seen from m = E/c^2. Radiation has momentum but no mass. The correct full equation is
E^2 = (p^2)*(c^2) + (m^2)*(c^4) where E is energy, p is momentum, c is the speed of light in a vacuum, and m is rest mass. For massive particles moving at low speeds the first term is negligible and so the equation simplifies to E = m*c^2. For massless particles (which always move at c in all reference frames) it simplifies to E = pc. Photon momentum is p = h/λ where h is Planck's constant and λ is wavelength. https://en.wikipedia.org/wiki/Momentum#Relativistic -- John Hasler j...@sugarbit.com Elmwood, WI USA
