Abstract
A hypothesis is proposed to explain resonant biological effects of microwaves. The interaction is thought to occur with low-frequency electronic transitions of transient triplet (or quartet etc.) molecules. As the transient molecules’ substate populations can be assumed to be far from thermal equilibrium the effect of resonant microwaves would be to equalize the population of two substates. Since the overall chemical reactivity of a molecule depends on its substate the result is an overall change of the molecules’ reaction rate which may cause further changes in the biochemical pathway. The model can in principle account for fixed frequencies, narrow linewidths and low saturation thresholds as are reported to be characteristic of biological sensitivity to millimeter waves [1-4], The interaction at the molecular level predicts identical resonances in widely different living objects. These resonances may offer a useful tool in biology and they can furthermore influence the discussion of microwave environmental impact.