Big Bang

In cosmology, the Big Bang is the scientific theory that the universe emerged extremely of a dense state and hot it has about 13,7 billion years. The theory is based on diverse comments that they indicate that the universe is in expansion in accordance with Friedmann-Robertson-Walker model based on General Relativity, amongst which most traditional and important it is heighten between redshifts and distances of far objects, known as Law of Hubble, and in the application of the cosmological principle.
In a more strict direction, the term Big Bang assigns the dense phase and hot for which it passed the universe. This important phase of beginning of the expansion of the universe, abusively compared with an explosion, thus was called for the first time, in this disdainful way, for the English physicist Fred Hoyle in the program The Nature of Things of radio BBC. Hoyle, proponent of the model - today abandoned - of the stationary universe, did not describe the Big Bang but he ridicules it. Although its origin, the expression Big Bang finished for losing its pejorative connotation and ironic to become the scientific name of the dense and hot time for which it passed the universe.
In 1927, the priest and Belgian cosmologist Georges Lemaitre (1894-1966), independently derived the equations from Friedmann to break das equations of Einstein and considered that the observed spectral shunting lines in nebulas had the expansion to universe, that for its time would be the result of the "explosion" of a "primeval atom".
In 1929, Edwin Hubble supplied to observational base to the theory of Lemaitre when measuring a shunting line for the red in the spectre ("redshift") of distant galaxies and to verify that this proportional age to its distances, was known as Law of Hubble-Humason.
The theory of the Big Bang is not an equal event to an explosion of the form that we know, even so the observed universe with the aid of the lenses of the modern space telescopes still describes a result of an explosion (a cosmic escape) who raises doubts if really it had something that blew up or if the cause of this observed dilatation was an explosion.
Some affirm that the term "Big Bang" is used as an approach to assign what also used to call "Cosmological Model Standard". This consists of an application of General Relativity to the Universe as a whole. This is a fact, at a first moment, assuming itself that the universe is homogeneous and isotropic in wide scale. At a second a moment it introduces fluctuations of density in the model and studies of evolution of these until the formation of galaxies.
The cosmological model standard extremely is well tested experimentally and made possible the forecast of the cosmic radiation of deep and the reason it enters the abundances of hydrogen and helium.
The current data is currently good to know the geometry of the universe.