Big bang

This article is about the cosmological model. For the sitcom, see The Big Bang Theory. For other uses, see Big Bang (disambiguation).

According to the Big Bang model, the universe expanded froman extremely dense and hot state and continues to expand today. A common analogy explains that space itself is expanding, carrying galaxies with it, like spots on an inflating balloon. The graphicscheme above is an artist's concept illustrating the expansion of a portion of a flat universe.Physical cosmology

Universe · Big Bang
Age of the universe
Timeline of the Big Bang
Ultimate fate ofthe universe
Early universe[show]Inflation · Nucleosynthesis
GWB · Neutrino background
Cosmic microwave background
Expanding universe[show]Redshift · Hubble's law
Metric expansion of spaceFriedmann equations
FLRW metric
Structure formation[show]Shape of the universe
Structure formation
Reionization
Galaxy formation
Large-scale structure
Galaxy filament
Components[show]Lambda-CDMmodel
Dark energy · Dark matter
Dark fluid · Dark flow
Timeline[show]Timeline of cosmological theories
Future of an expanding universe
Experiments[show]Observational cosmology
2dF · SDSSCOBE · BOOMERanG · WMAP · Planck
Scientists[show]Isaac Newton · Einstein · Hawking · Friedman · Lemaître · Hubble · Penzias · Wilson · Gamow · Dicke · Zel'dovich · Mather · Rubin · Smoot · others
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The Big Bang theory is the prevailing cosmological model of the early development of the universe.[1] The major premise of the Big Bang theory is that the universe was once in an extremelyhot and dense state that expanded rapidly (a "Big Bang"). This rapid expansion caused the young universe to cool and resulted in its present continuously expanding state. According to recentmeasurements, scientific evidence, and observations,[2][3] the original state happened around 13.7 billion years ago (see age of the Universe),[4][5] which can be referred to as the time that the Big Bang...