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The Friedmann–Einstein universe is a model of the universe published by Albert Einstein in 1931. [1] The model is of historic significance as the first scientific publication in which Einstein embraced the possibility of a cosmos of time-varying radius.
Einstein's static universe, aka the Einstein universe or the Einstein static eternal universe, is a relativistic model of the universe proposed by Albert Einstein in 1917. [ 1 ] [ 2 ] Shortly after completing the general theory of relativity , Einstein applied his new theory of gravity to the universe as a whole.
Because the Einstein universe soon was recognized to be inherently unstable, it was presently abandoned as a viable model for the universe. It is unstable in the sense that any slight change in either the value of the cosmological constant, the matter density , or the spatial curvature will result in a universe that either expands and ...
The cosmological constant was originally introduced in Einstein's 1917 paper entitled “The cosmological considerations in the General Theory of Reality”. [2] Einstein included the cosmological constant as a term in his field equations for general relativity because he was dissatisfied that otherwise his equations did not allow for a static universe: gravity would cause a universe that was ...
This model became known as the Einstein World or Einstein's static universe. [ 252 ] [ 253 ] Following the discovery of the recession of the galaxies by Edwin Hubble in 1929, Einstein abandoned his static model of the universe, and proposed two dynamic models of the cosmos, the Friedmann–Einstein universe of 1931 [ 254 ] [ 255 ] and the ...
Einstein's equations now relate the evolution of this scale factor to the pressure and energy of the matter in the universe. From FLRW metric we compute Christoffel symbols, then the Ricci tensor. With the stress–energy tensor for a perfect fluid, we substitute them into Einstein's field equations and the resulting equations are described below.
Einstein's model of a static universe was proved unstable by Arthur Eddington. The first direct observational hint that the universe was not static but expanding came from the observations of 'recession velocities', mostly by Vesto M. Slipher, combined with distances to the 'nebulae' by Edwin Hubble in a work published in 1929. [6]
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 ...