A new alternative approach to the statistical behavior of particle-particle collisions is introduced. The alternative approach is derived rigorously from well known mechanical laws;and the results given by it, quantitatively and qualitatively different from what the standard kinetic theory yields, can be directly checked with computer-simulated or realistic experiments. More importantly, from the introduction of it, a number of new concepts and new methodologies emerge, which might turn out to be very significant to the future development of nonequilibrium statistical mechanics.