Question

What happens when matter and antimatter collide?

Answer 1

Particle annihilation occurs and energy is released, typically as gamma radiation.

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An example is an electron-positron annihilation:

Trond Saue, "Relativistic Hamiltonians for Chemistry: A Primer", ChemPhysChem 2011, 12, p. 3086

(Electron Zitterbewegung basically means a local fluctuation of the electron position.)

When these collide, each particle has mass `m_e = 9.10938356 xx 10^(-31) "kg"`. Conservation of particles, angular momentum, and energy is observed, and for the low-energy case, we write this process as:

`""_(-1)^(0) e + ""_(1)^(0) e -> 2""_(0)^(0) gamma`

The energy released is `m_ec^2` per particle, so the total energy released is

`E = 2m_ec^2 = 2 cdot 9.10938356 xx 10^(-31) "kg" cdot (2.99792458 xx 10^8 "m/s")^2`

`= 1.64 xx 10^(-13) "J"`

or about `"1.022 MeV"` (i.e. `"0.511 MeV/photon"`).