3h 13min, jan 1, 0 y - Lepton Epoch, from 1 second to 3 minutes

Description:

After the majority (but not all) of hadrons and anti hadrons annihilate each other at the end of the Hadron Epoch, leptons (such as electrons) and antileptons (such as positrons) dominate the mass of the universe. As electrons and positrons collide and annihilate each other, energy in the form of photons.

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