I wrote: This possibility of a large interaction cross section ... >
It occurs to me that f/H will necessarily undergo collisions just like any other species (including neutrons). Presumably that kinetic energy will occasionally be passed on in inelastic collisions and reinflate the erstwhile epistemologically undetectable creatures. It is hard to see how a gas of f/H could avoid such collisions and reappear from out of the void into the world of scientifically detectable entities. Eric
