Answer:
This is one of the mysteries of quantum mechanics - a single photon in classical mechanics is sent out in a circular arc - but when the arc interacts with a distant object the entire wave front collapses and delivers the entire energy of the photon to the object in question.
An analogy has been give as a pop bottle thrown into the water in New York with its energy spreading out in a circular arc and at some time later the wave front strikes a pop bottle in the water in Japan with the result of the wave front delivering its entire energy to the bottle with the bottle jumping out of the water.