Degrees of Freedom in the Early Universe

This animation shows the dramatic change in the number of degrees of freedom as the temperature drops over the first second after the big bang. The two large reductions in degrees of freedom correspond to the confinement transition, where all the quarks and gluons are bound up in the neutrons and protons, and the weak freeze-out, where the weak interactions become too slow to keep the neutrinos in thermal equilibrium with the rest of the Universe. The first occurs about one millionth of a second after the bang and the second occurs about 1 second after the bang. Usage: Click "Play" to begin and when the button turns red to continue. Click "Stop" to pause. "Home" returns to the beginning.