On April 1, 1952, the Big Bang Theory was proposed by Ralph Alpher, George Gamow, and Hans Bethe in a paper published in the scientific journal Physical Review. The paper’s formal title was “The Origin of Chemical Elements,” but has since come to be referred to simply as the Alpher–Bethe–Gamow paper, or αβγ for short.

The Big Bang Theory, or simply the Big Bang, is the established cosmological model of the origin of the observable universe. There are numerous ways in which this model is upheld scientifically, the first of which was proposed in the groundbreaking Alpher–Bethe–Gamow paper.

The publication demonstrated how the Big Bang model would account for the observable abundance and proportionality of elements in the universe, such as hydrogen, helium, and heavier elements. Although the paper did not initially incorporate certain processes involved in the formation of heavier elements (such as stellar nucleosynthesis or the creation of elements via nuclear fusion in stars), it opened the door for other astrophysicists and researchers to explore Big Bang nucleosynthesis (the creation of elements during the very early phases of the universe).

The vast majority of ordinary matter in the observable universe, referred to as baryonic matter, is hydrogen and helium, the elements with the fewest numbers of protons and neutrons. The Big Bang Theory, when applied to the measurable abundance of these elements and their proportions, is able to correctly account for the current states of both.