Dr. Edward Dowdye is a laser optics engineer and former NASA physicist. In this presentation, Dr. Dowdye points out that General Relativity predicts we should see light being “bent” around objects in space, yet we don’t. Instead, we only see light being bent when it passes through fields of plasma. It starts a little slow, but by the time you get half-way through you’ll get the picture of what Dr. Dowdye is trying to explain.
Dr. Dowdye never mentions this in his lecture, but it is a known fact that when light rays pass through certain types of plasma, they can be “bent” because the refractive index of the plasma increases with the strength of the electric field. This change in the refractive index of a plasma is called “self-focusing.” Self-focusing in a plasma can occur through thermal, relativistic and ponderomotive effects. This effect is capable of explaining why light is distorted as it passes close to the Sun. It’s not because of the “gravitational gradient” that Dowdye suspects.
Since plasma self-focusing is a known effect of light passing through a plasma, any explanation of light refraction through a plasma must include these effects. In all General Relativity papers that attempt to explain why we observe refraction of light very near to the Sun, they fail to account for self-focusing effects.