Detailed measurements of the expansion rate of the universe place the Big Bang singularity at an estimated 13.787 ± 0.020 billion years ago, which is considered the age of the universe.

The initial singularity is a singularity predicted by some models of the Big Bang theory to have existed before the Big Bang. The instant immediately following the initial singularity is part of the Planck epoch, the earliest period of time in the history of our universe.

Scientists think the CMB began propagating through the universe about 380,000 years after the Big Bang, when atoms began to form and the universe became transparent, according to the European Space Agency. However, there is no direct evidence of the original singularity.