According to quantum electrodynamics, there is a small butfinite probability that two photons may scatter against each other.Suppose two photons, with wavelengths λ1 and λ2, collide head-on.Compute the wavelength of one of the photons after the collision,if its scattering angle is θ. (The energy of a photon withwavelength λ is ̄hω, where ω = 2πc/λ.)
