George Gamow, sometimes Gammoff; born Georgiy Antonovich Gamov was a Soviet and American polymath, theoretical physicist and cosmologist. He was an early advocate and developer of Lemaître's Big Bang theory. Gamow discovered a theoretical explanation of alpha decay by quantum tunneling, invented the liquid drop model and the first mathematical model of the atomic nucleus, worked on radioactive decay, star formation, stellar nucleosynthesis, Big Bang nucleosynthesis, and molecular genetics.

The Big Bang is a physical theory that describes how the universe expanded from an initial state of high density and temperature. It was first proposed in 1931 by Roman Catholic priest and physicist Georges Lemaître when he suggested the universe emerged from a "primeval atom". Various cosmological models of the Big Bang explain the evolution of the observable universe from the earliest known periods through its subsequent large-scale form. These models offer a comprehensive explanation for a broad range of observed phenomena, including the abundance of light elements, the cosmic microwave background (CMB) radiation, and large-scale structure. The overall uniformity of the universe, known as the flatness problem, is explained through cosmic inflation: a sudden and very rapid expansion of space during the earliest moments. However, physics currently lacks a widely accepted theory of quantum gravity that can successfully model the earliest conditions of the Big Bang.