Separating Waveform from quantium Since light spreads out in all directions from it's source how far must it travel to become individual photons. I am not suggesting that this is a practical but there must be an answer. Or another way to look at it, What is the density of photons in a given level of light or for that matter any electromagnet wave.

Since light spreads out in all directions from it's source, how far it must travel to become individual photons? Can we consider, that is, that as the intensity of light becomes weaker as it spreads, we measure in fact less photons until only a few remain?

Or another way to look at it: What is the density of photons in a given beam of light or for that matter any electromagnetic wave?