Mass behaves differently than other quantum numbers when combining matter and antimatter, as it adds together rather than cancels out. The discussion clarifies that mass is not a quantum number and emphasizes that antiparticles possess positive mass, not negative. This is explained through the energy-momentum four-vector, which is always positive, and the principle that energy is inherently positive according to the equation E=mc². The original question is deemed unclear and inappropriate for the homework forum, as it stems from the poster's personal particle model inquiries. The conversation highlights the need for clarity in scientific questions and proper forum categorization.
