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[[Image:Universe expansion.png|right|thumb|250px|According to the Big Bang theory, the universe emerged from an extremely dense and hot state called the ''original singularity''.]]  

[[Image:Universe expansion.png|right|thumb|250px|According to the Big Bang theory, the universe emerged from an extremely dense and hot state called the ''original singularity''.]]  

[[Image:End of universe.jpg|right|thumb|250px|According to the Big Bang theory, the 3 possible geometry of the universe depends on value of the ''[[cosmological constant]]''.]]

[[Image:End of universe.jpg|right|thumb|250px|According to the Big Bang theory, the 3 possible geometry of the universe depends on value of the ''[[cosmological constant]]''.]]

The '''Big Bang Theory''' is the current dominant scientific theory explaining the creation of the Universe.  It models the Universe as expanding from a very hot, dense state approximately 13.7 billion years ago. It was first proposed by [[Georges-Henri Lemaitre]] and evidence for the expansion was observed by [[Edwin Hubble]]<ref>Hubble, E. Proceedings of the National Academy of Sciences of the United States of America, Volume 15, Issue 3, pp. 168-173.</ref>. Later [[George Gamow]] predicted that the Big Bang would leave an observable microwave background radiation (or CMBR). This radiation was subsequently discovered by [[Bell Labs]] and found to be close to that predicted by Gamow (Gamow predicted a background radiation level equivalent to a roughly 3 K black body object, and the observed level is that of a 2.725 K body).  On November 18, 1989, the COBE (Cosmic Background Explorer) satellite was launched to map the variations in the microwave background radiation<ref>[http://lambda.gsfc.nasa.gov/product/cobe/]</ref>.  On June 30. 2001, the WMAP (Wilkinson Microwave Anisotropy Probe) satellite was launched, which could map the microwave background radiation in even greater detail<ref>[http://map.gsfc.nasa.gov/]</ref>.

The '''Big Bang Theory''' is the current dominant scientific theory explaining the creation of the Universe.  It models the Universe as expanding from a very hot, dense state approximately 13.7 billion years ago. It was first proposed by [[Georges-Henri Lemaitre]] and evidence for the expansion was observed by [[Edwin Hubble]]<ref>Hubble, E. Proceedings of the National Academy of Sciences of the United States of America, Volume 15, Issue 3, pp. 168-173.</ref>. Later [[George Gamow]] predicted that the Big Bang would leave an observable microwave background radiation (or CMBR). This radiation was subsequently discovered by [[Bell Labs]] and found to be close to that predicted by Gamow (Gamow predicted a background radiation level equivalent to a roughly 3 K black body object, and the observed level is that of a 2.725 K body).

The term "Big Bang" implies an explosion of matter into pre-existing space, but the theory actually indicates that space is dynamic and more space is constantly created in the interstices between particles as the density of the universe falls.  Big bang theorists state that the Hubble [[redshift]] is a consequence of this stretching of the fabric of space.

The term "Big Bang" implies an explosion of matter into pre-existing space, but the theory actually indicates that space is dynamic and more space is constantly created in the interstices between particles as the density of the universe falls.  Big bang theorists state that the Hubble [[redshift]] is a consequence of this stretching of the fabric of space.