Big Bang Theory

Big Bang is a physical theory that explains how the universe expanded from an initial state of high density and temperature. Various cosmological models of the Big Bang theory explain the abundance of light elements, cosmic microwave background (CMB) radiation and the large-scale structure of the universe.

The flatness of the universe is explain by the theory of cosmic inflation - a sudden and very rapid expansion of the universe in its early stages. However, physics currently lacks a theory of quantum gravity that can model the initial conditions of the Big Bang.

The ΛCDM Model is described as the standard model of Big Bang cosmology due to it's simplicity and ability to explain various properties of the cosmos.