http://physics.aps.org/articles/v6/40 Some cosmic rays are electrons, some are positrons, and some are other things. Focusing only on the first two, the AMS experiment in the space station finds that the ratio of positrons to electrons depends upon the ray-energy. ENERGY positron fraction 0.5 GeV 0.095 to 0.11 7 GeV 0.02 (min) 100 GeV 0.11 to 0.15 300 GeV 0.15 Why? These energies seem too large to be explained directly by any set of nuclear reactions. There must be cosmic accelerators out there producing these hotties, which makes it mysterious why the positron fraction should depend in this funny way upon energy. Another speculation is that somehow these are coming from hypothetical superheavy "dark matter" particles, in which case this is telling us that their masses ought to be within this energy range. -- Warren D. Smith http://RangeVoting.org <-- add your endorsement (by clicking "endorse" as 1st step)