Figure 14-8Early History of the Universe Current theory holds that, as the universe cooled, the four forces separated from their initially unified state. The inflationary epoch lasted from 10-36 seconds to 10-32 seconds after the Big Bang. Quarks became confined together, thereby creating neutrons and protons 10-6 seconds after the Big Bang. The universe became transparent to light (that is, photons decoupled from matter) when the universe was about 1.6 × 1013 seconds (380,000 years) old. The physics of the Planck era is presently unknown.