Hello All, As far as the Newtonian mechanics and Einstein's GR is concerned, I am a little bit confused in the following things: (a) Concerning the bending of light due to gravity: Some lectures and opinions show that light bends due to the force of gravity as shown in the event of a solar eclipse, light bends and takes a different route before reaching the observer. Another argument shows that as photons are mass less, hence how can they be affected by gravity? The curvature of spacetime allows the photons to take the curved path. WHICH ONE IS CORRECT? In case we use F= G m1m2/r^2 and use photons, substituting m=0 for mass less photons, we get F=0. From that can we tell that for photons there is no force? (b) Concerning the red shift and blue shift: It shows that photons coming out of gravitation zone, looses energy and hence the wavelength becomes longer and causes red shift and vice-verse causing the blue shift. Here the energy of the photon is affected by gravity while IN THE ABOVE CASE IT IS NOT. AM I GETTING SOMETHING WRONG? Thanks.