Not sure whether this post should be in the relativity forum. However a few years down the line it could be in-between relativity and QM. What is the process of creation of gravity? How does gravity effect two quantum entangled photons?....say when one of them passes through a bend in space-time....like the one that surrounds the earth. Mass bends space-time. What does space-time bend in? Is there still a straight line (that would be without gravity) when space time is bent? Can a hole/tear be created in space-time? Which things are unaffected by gravity? What is the effect of gravity on gyroscopes?