Oh no I understand that very well, I’m well versed in statistical mechanics. The thing is that the cross-section of the targets remain low, and therefore the am

Oh no I understand that very well, I’m well versed in statistical mechanics. The thing is that the cross-section of the targets remain low, and therefore the amplitude of the scattering matrix remains pretty low. It’s actually pretty unlikely to successfully trigger off a divergent chain reaction. To use a nuclear analogy, it’s the density is well below a critical density (or rather, it’s far from a critical geometry).