Theory · proposed 1931 CE
The Big Bang
History of Astronomy
The theory
The theory that the universe expanded from an extremely hot, dense early state, first proposed by Georges Lemaître as the 'primeval atom'. The expansion of the universe and, decisively, the discovery of the cosmic microwave background in 1965 established it as the leading account of cosmic history.
Developed by
Confirmed by
Knowledge connections
- Confirmed byThe Expansion of the Universe
- Confirmed byThe Cosmic Microwave Background
- Developed byGeorges Lemaître
- Part ofModern Astronomy
- Required byThe Big Bang
Sources & references
The primary and reference sources this topic draws on.
- NASANational Aeronautics and Space Administration
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.
- BritannicaEncyclopaedia Britannica
General reference for the history of astronomy, biographies, and cultural context.