Matter and Antimatter

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© Fermilab.

In the Standard Model, every particle has a corresponding antiparticle. Antiparticles have the same mass as their partners, but the opposite electric charge. When a particle meets its antimatter partner, the pair annihilates, releasing the energy of the original particles as photons. It is generally assumed that matter and antimatter were produced in equal amounts when our universe began, leaving theorists to puzzle out why the matter we are made of is left over from the initial annihilation. (Unit: 1)