| hadron era | is followed by lepton era |  |
| has density ρ = 1093 g cm-3 |  |
| has duration 10-5 s |  |
| has synonym hadron barrier |  |
| is preceded by Planck era |  |
| has start time 10-43 s after Big Bang |  |
| has definition The Big Bang era when the Universe was matter-dominated, containing many hadrons in equilibrium with the radiation field and when kT ≈ mπ. The hadron era ended when the characteristic photon energy fell below the rest mass of a pion or π-meson (270 electron masses), and very few hadrons remained (about one hadron for every 108 photons). |  |
| has definition The Big Bang era during which quantum and general-relativistic effects are expected to modify each other in an unknown way. |  |
| is a kind of Big Bang era |  |
| Big Bang era | has temperature |  |
| event | has time of occurrence |  |