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In astrophysics, the term Big Bang is used both in a narrow sense to refer to the interval of time roughly 13.7 billion years ago when the photons observed in the microwave cosmic background radiation acquired their black-body form, and in a more general sense to refer to a hypothesized point in time when the observed expansion of the universe ( Hubble's law) began.

According to the Big Bang theory, the universe originated in an infinitely dense and physically paradoxical singularity. Space has expanded with the passage of time, objects being moved farther away from each other.

In cosmology, the Big Bang theory is the prevailing scientific theory about the early development and shape of the universe. The central idea is that the observation that galaxies appear to be receding from each other can be combined with the theory of general relativity to extrapolate the conditions of the universe back in time. This leads to the conclusion that as one goes back in time, the universe becomes increasingly hot and dense.

There are a number of consequences to this view. One consequence is that the universe now is very different than the universe in the past or in the future. The Big Bang theory predicts that at some point, the matter in the universe was hot and dense enough to prevent light from flowing freely in space. That this period of the universe would be observable in the form of cosmic background radiation (CBR) was first predicted in the 1940s, and the discovery of such radiation in the 1960s swung most scientific opinion against the Big Bang theory's chief rival, the steady state theoryFor alternative meanings see steady state (disambiguation). The steady state theory is a model developed in 1949 by Fred Hoyle, Thomas Gold and others as an alternative to the Big Bang theory. Although the model had a large number of supporters among cosm.

Using current physical theories to extrapolate the Hubble expansion of the universe backwards leads to a gravitational singularityA gravitational singularity occurs when an astrophysical model, typically based on general relativity, predicts a point of infinite curvature. The term is closely related to the mathematical meaning of "singularity": a gravitational singularity occurs whe, at which all distances become zero and temperatures and pressures become infinite. What this means is unclear, and most physicists believe that this is because of our limited understanding of the laws of physicsThe following are some of the unsolved problems in physics . This is an incomplete list of outstanding problems in physics. Some of these problems are theoretical, meaning that existing theories seem incapable of explaining some observed phenomenon or exp with regard to this type of situation, and in particular, the lack of a theory of quantum gravityQuantum gravity is the field of theoretical physics attempting to unify the theory of quantum mechanics, which describes three of the fundamental forces of nature, with general relativity, the theory of the fourth fundamental force: gravity. The ultimate.

There are actually many theories about the Big Bang. Some theories purport to explain the cause of the Big Bang itself, and as such have been criticized as being modern creation myths. Some people believe that the Big Bang theory lends support to traditional views of creation, for example as given in GenesisThis article is about Genesis the first book of the Hebrew Bible. See Genesis (disambiguation) for other usages of the word. Genesis ( Greek: , having the meanings of "birth", "creation", "cause", "beginning", "source" and "origin"; translated from Hebrew, while others believe that all Big Bang theories are inconsistent with such views. The relationship between religion and the Big Bang theory is discussed below.



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