Every discovered fundamental particle in the universe has it’s antiparticle, that antiparticle has the same mass but opposite charge. There is an ongoing theory for a long time that says there is exception to this rule. They named it the “angel particle”

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Every discovered fundamental particle in the universe has it’s antiparticle, that antiparticle has the same mass but opposite charge. There is an ongoing theory for a long time that says there is exception to this rule. They named it the “angel particle”