It should be noted that there are a number of situations where this formalism is not valid. Firstly, in the case of strong light-matter coupling , Fermi's Golden rule (Equation ) becomes invalid. In this case, an exact non-adiabatic quantum electrodynamics model will be required . Secondly, Equation 74 is analogous to an electrodynamical treatment of the energy gap law, and therefore in the case where the vibronic coupling is too large, perturbation theory may not be valid . Thirdly, a number of external factors have not yet been included in the electrodynamical internal conversion cast. These include, but are not limited to, cavity dielectric effects or optical cavity loss phenomena, which have all been shown to strongly influence light-matter interactions .