Does it work like that.. that a changing EM field in-phase (actually, like.. 180 degre (spell?) out-of phase) with the incoming photon would absorb it? .. when sound waves of 180 degre.. (spell) out of phase with each other would cancel each other out. The same thing would happen with EM radiation - photons, right? Yes, think i know that.. :) And if the EM field changing in (out of) phase would absorb it - it wouldn't do it instantly. It would decrease in energy and while it decreases in energy, it would decrease in frequency, right? .. (edited: and I just thought - if it changes frequency, it is not in-phase anymore...) Another question while we are at this - where does the energy go in two wave cancellation?