1. ""http://en.wikipedia.org/wiki/Gravitation" [Broken]" is a general term describing the attractive influence that all objects with mass exert on each other. 2. The "http://en.wikipedia.org/wiki/Photon" [Broken] is massless,has no electric charge and does not decay spontaneously in empty space. My question is why does gravity affect particles without mass (like photons) ?