In Quantum Field Theory, I am led to believe that there is a different field for each type of particle. When particles interact, it is an exchange of vibration between the fields. What mechanism is at play when one field influences another in this way? It seems I've only ever found half-explanations of this which argue in circles, like saying that the electron is affected by the photon first then the photon affects the other electron (or whatever), but a photon is just another excitement of a field, so the question still isn't answered. What's between the fields which communicates that one should use its vibrations to make another vibrate?