Why does religion still exist?  It is something we have pondered many times because its demise has been predicted for centuries.    It turns out that religious people are happier, studies show, and that makes sense; answers to otherwise unsolvable puzzles are comforting and if you've ever been to an 'skeptic' conference, the only times they are happy are when they are making fun of religion so, technically, religion even makes atheists happier.
We know that light has mass and that beaming enough light at something can push it away - solar sails that will move a craft through the cosmos are based on this idea and NASA tested that concept earlier today when it launched NanoSail-D, a nanosatellite (cubesat) which will unfold to a 100 square foot polymer sail and travel in low earth orbit for a few months.

solar sail on a cubesat.
Sails?  We don't need no stinking sails.  Credit: NASA