March 24, 2017
Although supersymmetric theories are being ruled out as of 2017, requiring heavier particles, dark matter is thought to be electrically neutral, gravitationally interacting matter, symmetric to normally gravitationally interacting matter. In positive/negative electrostatic forces, opposites attract, and in symmetry with gravity, there is one of two possibilities: either 1.) opposites repel, and the same attract (so positive attracts positive, and negative attracts negative), or 2.) gravity attracts all (negative and positive), and negative gravity repels all (negative and positive). Number two seems more likely, as otherwise negative gravity would have formed clumps instead of halos in the dark matter sector.