As far, as I understand, in quantum field theory one photon can't be absorbed by to particle systems like atoms, or can't be scattered on two single particles, like free electrons.
- If to consider electromagnetic radiation as distribution of changes of values of electromagnetic field at space, i.e. as a wave, how many particles then, can interact with "one same" radiation?
*fig 1 - Example, emerald circles - em waves, pink dots - electrons
What will happen in the case, illustrated above? Will one (random?) of two electrons somehow interact (scatter) with the wave, and just after that the second one will lose ability to interact with the same wave, because the last one will disappear? Or will they both interact with em wave simultaneously?
- How does it corresponds with considering em radiation as a particle - photon?
If to consider an em wave as literally changes of electrical field strength values at some points at some time, then two electrons must be affected by same em field, and simultaneously (considering the case, illustrated above).
Some stuff is intuitively proving it, like Huygens–Fresnel principle.
Or the fact that all light sources, as I understand always emit light radially (or spherically, do not know hot to call it) in all directions, even lasers. It can be narrowed (like in case of laser), though it still will diverge.
And, considering the fact from paragraph above, I've read somewhere, and it should be logical, that if em radiation is infinitely "stretches", and at the same time its energy is constant, then, energy (and hence $E$) per area unit should decrease.
If $E$ per area is considering by someone in physics, that means that particles per can absorb not whole em wave, but only part, that corresponds to the area, that particle is occupying.