From what I gather, the negative mass repels the positive mass (which is thus accelerated away), and the positive mass attracts the negative mass, which (becaus

From what I gather, the negative mass repels the positive mass (which is thus accelerated away), and the positive mass attracts the negative mass, which (because it has negative mass) is thus also accelerated away. Now, the kinetic energy of the positive mass grows, but the kinetic energy of the negative mass is negative and falls (because its mass is negative...), so energy is conserved. EDIT to add: I think I gathered wrong. Apparently, there is runaway motion (same direction), energy and momentum is still conserved (since one mass is negative), and since total mass is zero, the two particles reach speed of light. Intriguing. See paper.