I recently ran across a guy that shows how what we believe to be gravitational lensing could actually be more readily attributable to the plasma atmosphere of the sun. And it does lead to the conclusion that gravitational acceleration may not be the root cause of the bending of light. We all see the lensing effect our own atmosphere has on both the sun and the moon, every day when these bodies are close to the horizon. If you have the time, listen to this guy as he gives a lecture on this alternate viewpoint. Of course if this fact based veiwpoint is correct, it does suggest right away that John Titor's laser picture is debunked again, because gravity has no effect on light at all.