I read this article http://hitoshi.berkeley.edu/public_html/susy/susy.html and one of the things it suggested was that "One of the best candidates for Dark Matter is the lightest supersymmetric particle." So i have a question. (doesnt have anything to do directly with the article itself but...) Given: We have a lot more dark matter than regular matter. There's enough gravitation generated by regular matter so that it can collapses into black holes. I realize that dark matter is supposed to be very weakly interacting with normal matter but i haven't heard/read anyone comment on how it interacts with itself. We have enough dark matter so whats preventing it from collapsing into a dark matter black hole for example? Basically, why is gravity able to lump up regular matter on a small scale (stars & black holes) and dark matter only appears to lump up when viewed spread over large distances like the scales of galaxies or clusters of galaxies?