On 4/15/15, Warren D Smith <warren.wds@gmail.com> wrote:
http://www.eso.org/public/archives/releases/sciencepapers/eso1514/eso1514a.p... Richard Massey, Liliya Williams, 20 others: The behaviour of dark matter associated with 4 bright cluster galaxies in the 10 kpc core of Abell 3827, MNRAS (2014?) 15 pages
now finds fairly direct evidence dark matter does interact with other dark matter particles (which, if so, I have previously argued here, but they do not argue, must be due to a new "dark force") with a cross-section (they claim) of (1.7 +- 0.7) * 10^(-4) cm^2/gram. The previous paper had claimed an upper bound of 0.47 cm^2/gram.
--I point out that in (what I call) "cosmical units", where the natural quantities are c=299792458 meter/sec, G = 6.67×10^(-11) meter^3/kg/sec^2, Lambda = 1.2×10^(-35)/sec^2 the "naturally expected" value for the dark matter cross section would be (by "dimensional analysis") G/(c*Lambda^(1/2)) = 0.64 cm^2/gram. -- Warren D. Smith http://RangeVoting.org <-- add your endorsement (by clicking "endorse" as 1st step)