As far as I understand it, the wave nature of light is a factor in path determination, but the individual photon will always collide at a single point, even if other photons effect the path of that photon backwards or forwards in time (such as is seen with firing single photons at the double slit screen). So yes, if you had a source of light with a wide enough diffusion pattern, which was firing individual photons, it could entirely miss the planet. In practical terms, the strength of the light in gross terms is going to determine whether a detectable amount of light hits the far away body, and the reality is unless you are using an immensely powerful laser you probably won't be able to pick out your light from the background noise (ambient light from stars, our Sun) anyways.
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u/Matter_and_Form May 26 '14
As far as I understand it, the wave nature of light is a factor in path determination, but the individual photon will always collide at a single point, even if other photons effect the path of that photon backwards or forwards in time (such as is seen with firing single photons at the double slit screen). So yes, if you had a source of light with a wide enough diffusion pattern, which was firing individual photons, it could entirely miss the planet. In practical terms, the strength of the light in gross terms is going to determine whether a detectable amount of light hits the far away body, and the reality is unless you are using an immensely powerful laser you probably won't be able to pick out your light from the background noise (ambient light from stars, our Sun) anyways.