Q:

Electromagnetic EM waves - How they coexist in same space and time without signal impact?

I'm having difficulty understanding how 2 EM waves from 2 sources can co exist in same space and time, without changing one another from a Quantum Electrodynamics Perspective.
If a charged source emits photons which excite electrons in Field Region X.... then how can another wave from a different source not impact the first EM wave due to an increase in Electron Excitation on ((same)) electrons in same Field Region X in same time.
I didn't think different electrons were excited by different wave sources... otherwise, how can Electron State = Wave1 .... when another Force from Wave2 is exerted on it?

A:

The electrons will be excited by a superposition (sum) of the two EM waves. The waves will pass through each other much like waves on a pond. There is no differentiation between waves from different sources.
Occasionally it is possible to run in to nonlinearities that depend on the overall amplitude of the EM waves in question, and in this case all of the waves would be affected.

