I understand that a black hole bends the fabric of space time to a point that no object can escape. I understand that light travels in a strait line along space time unless distorted by gravity. In Newton's Law of Universal Gravitation, the mass of both objects must be entered. If space time is being bent by gravity then light should follow that bend in space time. Why is that if a massless photon should not be effected by gravity in by Newton's equations? What am I missing?