Search results
Results From The WOW.Com Content Network
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 second equation says that the kinetic energy (seen from the origin) of a particle of unit mass moving with the expansion plus its (negative) gravitational potential energy (relative to the mass contained in the sphere of matter closer to the origin) is equal to a constant related to the curvature of the universe. In other words, the energy ...
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 ...
According to the Hartle–Hawking proposal, the universe has no origin as we would understand it: before the Big Bang, which happened about 13.8 billion years ago, the universe was a singularity in both space and time. Hartle and Hawking suggest that if we could travel backwards in time towards the beginning of the universe, we would note that ...
Gamow's work led the development of the hot "big bang" theory of the expanding universe. He was the earliest to employ Alexander Friedmann's and Georges Lemaître's non-static solutions of Einstein's gravitational equations describing a universe of uniform matter density and constant spatial curvature. Gamow's crucial advance would provide a ...
The image was an adaptation from various generic charts depicting the growth of the size of the observable universe, for both the standard model and inflationary model respectively, of the Big Bang theory. The early, hot universe appears to be well explained by the Big Bang from roughly 10 −33 seconds onwards, but there are several problems.
Current astronomical observations, show that the universe is expanding, thus the BGV implies that there must be a boundary or singularity in the history of the universe. This singularity has often been associated to the Big Bang. However the theorem does not tell if it is associated to any other event in the past.