In special relativity, a photon can be thought of as having a “mass” of m = Ev/c^2 . This suggests that we can treat a photon that passes near the sun in the same way as Rutherford treated an alpha particle that passes near a nucleus, with an attractive gravitational force replacing the repulsive electrical force. Adapt Eq. (4.29) to this situation and find the angle of deflection θ for a photon that passes b = R_sun from the center of the sun. The mass and radius of the sun are respectively 2.0 x 10^30 kg and 7.0 x 10^8 m.