Actually thinking a bit more, I think Gene Salamin's calculation, even AFTER my major numerical adjustments, still is good enough to destroy the usual weakly interacting dark matter hypothesis (and/or the claims in that paper). See, dark matter particles whatever they are are presumably at least 300 times more massive than protons otherwise we would have detected DM in accelerators already. And if they interact via weak force and gravity alone, each particle must have a very small cross section, much smaller than the squared-radius of a proton, in fact of order (10^(-17) meter)^2 = (10^(-15) cm)^2 = 10^(-30) cm^2. So I conclude that weakly interacting dark matter must have cross section no larger than about 10^(-30)*6*10^23 / 300 = 2 * 10^(-9) cm^2 per gram. But the paper under discussion claims to agree with astronomical observation, it must be at least 0.1 cm^2 / gram. Oops. So we conclude: either the paper's 0.1 claim is bullshit, or the only-weakly interacting DM hypothesis is bullshit, or both. QED. -- Warren D. Smith http://RangeVoting.org <-- add your endorsement (by clicking "endorse" as 1st step)