# Forces involved in annihilation event

Combustion can create energy by breaking/creating bonds between atoms via the electromagnetic force to produce a resultant lower energy system. Nuclear fusion and fission processes can create energy by producing particular nuclei which are more stable than their precursors via the strong force which lowers the resultant system's energy.

Matter and its corresponding antimatter can create energy by annihilation. But what is the force that mediates this process? Why does this force not operate similarly during matter-matter or antimatter-antimatter interaction?

Annihilation is the result of the combination of the two systems, quantum mechanics and special relativity. In special relativity, every particle and system of particles is represented by a four vector, and at the framework where the system is at rest, i.e. the momentum zero the mass of the system is identical with energy. $$m_0^2c^2=\biggl(\frac{E}{c}\biggr)^2-||\mathbf{p}||^2$$ Or in natural units where $c=1$, $$m_0^2=E^2-||\mathbf{p}||^2$$ Quantum mechanics then enters, which has conserved quantum numbers, and thus does not allow everything to annihilate with everything else in an interaction. Quantum numbers have to be conserved, and that is why baryons annihilate with antibaryons ,(conservation of baryon number), electrons with positrons (conservation of lepton number) etc.