The quark epoch ended when the universe was about 10−6 seconds old, when the average energy of particle interactions had fallen below the binding energy of hadrons. The following period, when quarks became confined within hadrons, is known as the hadron epoch.
The quark epoch concluded when the universe was approximately 10−6 seconds old, as the average energy of particle interactions dropped below the binding energy of hadrons. The subsequent period, during which quarks were confined within hadrons, is referred to as the hadron epoch.