A field force propagates at the speed of light forever. Suppose this field force causes a quantum reaction when it encounters certain particles. This reaction releases a gamma ray burst in all directions. Now suppose an observer is sitting in the direction perpendicular to the asymptote of the gamma producing event. {pardon the unwieldiness here is a visual representation: )-> } Does he notice an increment between detecting the gamma ray, and detecting the field force? Or does he experience it all at once, as an event horizon?