The Big Bang theory was first proposed in modern form by the Belgian priest‑physicist Georges Lemaître in the late 1920s, so he is generally credited as the originator of the theory.

Quick Scoop: Core Answer

  • Georges Lemaître suggested that the universe began from a very dense, tiny “primeval atom” that expanded, which is essentially the idea now called the Big Bang theory.
  • Later, other scientists such as George Gamow, Ralph Alpher, and Robert Herman developed the theory further, while Edwin Hubble’s observation of the expanding universe provided key evidence for it.
  • The actual phrase “Big Bang” was coined years later by astronomer Fred Hoyle during a 1949 radio broadcast, originally as a contrasting label to his preferred steady‑state model.

Who Gets Credit?

  • Most historians of science now describe Lemaître as the one who “formulated” or “originated” the modern Big Bang model, because he combined Einstein’s general relativity with galactic red‑shift data to argue for an expanding universe with a finite age.
  • Alexander Friedmann earlier found mathematical expanding‑universe solutions to Einstein’s equations, but his work was mainly theoretical and did not tie the math to astronomical observations in the same way Lemaître did.
  • Hubble’s distance–redshift data, published in 1929, then strongly supported the expanding‑universe picture Lemaître had already proposed, and this link is one reason the law of expansion is now often called the Hubble–Lemaître law.

Mini Timeline

  1. 1922–1924: Friedmann writes expanding‑universe solutions to Einstein’s equations (no full physical “Big Bang” scenario yet).
  1. 1927: Lemaître publishes his model of an expanding universe starting from a primeval state, effectively the first full Big Bang–type theory.
  1. 1929: Hubble publishes empirical evidence that galaxies are receding, consistent with an expanding universe.
  1. 1940s–1950s: Gamow and collaborators develop hot Big Bang nucleosynthesis, and Hoyle popularizes the term “Big Bang” (even though he opposed the idea at first).

In short: if the question is “who discovered Big Bang theory,” the most historically accurate one‑name answer is Georges Lemaître.

Information gathered from public forums or data available on the internet and portrayed here.