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The Big Bang is a physical theory that describes how the universe expanded from an initial state of high density and temperature. [1] The concept of an expanding universe was scientifically originated by physicist Alexander Friedmann in 1922 with the mathematical derivation of the Friedmann equations.
After some reformulation, the Big Bang has been regarded as the best theory of the origin and evolution of the cosmos. Before the late 1960s, many cosmologists thought the infinitely dense and physically paradoxical singularity at the starting time of Friedmann's cosmological model could be avoided by allowing for a universe which was ...
The CMB is landmark evidence of the Big Bang theory for the origin of the universe. In the Big Bang cosmological models, during the earliest periods, the universe was filled with an opaque fog of dense, hot plasma of sub-atomic particles. As the universe expanded, this plasma cooled to the point where protons and electrons combined to form ...
The traditional model of the Big Bang. The use of only general relativity to predict what happened in the beginnings of the universe has been heavily criticized, as quantum mechanics becomes a significant factor in the high-energy environment of the earliest stage of the universe, and general relativity on its own fails to make accurate predictions.
About 10 seconds after the Big Bang the temperature of the universe falls to the point at which new lepton–antilepton pairs are no longer created and most remaining leptons and antileptons quickly annihilated each other, giving rise to pairs of high-energy photons, and leaving a small residue of non-annihilated leptons. [31] [32] [33]
Big Bang nucleosynthesis predicts a primordial abundance of about 25% helium-4 by mass, irrespective of the initial conditions of the universe. As long as the universe was hot enough for protons and neutrons to transform into each other easily, their ratio, determined solely by their relative masses, was about 1 neutron to 7 protons (allowing ...
Its discovery and detailed observations of its properties are considered one of the major confirmations of the Big Bang [1]. Background radiation is largely homogeneous and isotropic. A slight detectable anisotropy is present which correlates to galaxy filaments and voids [2] [3]. The discovery (by chance in 1965) of the cosmic background ...
The Big Bang theory, which explains the Evolution of the Universe from a hot and dense state, is widely accepted by physicists.. In astronomy, cosmogony is the study of the origin of particular astrophysical objects or systems, and is most commonly used in reference to the origin of the universe, the Solar System, or the Earth–Moon system.