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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 ...
The Einstein field equation is often written as + =, with a so-called cosmological constant term. However, it is possible to move this term to the right hand side and absorb it into the stress–energy tensor T a b {\displaystyle T^{ab}} , so that the cosmological constant term becomes just another contribution to the stress–energy tensor.
In cosmology, the cosmological constant problem or vacuum catastrophe is the substantial disagreement between the observed values of vacuum energy density (the small value of the cosmological constant) and the much larger theoretical value of zero-point energy suggested by quantum field theory.
a cosmological constant, denoted by lambda (Λ), associated with dark energy; the postulated cold dark matter, denoted by CDM; ordinary matter. It is the current standard model of Big Bang cosmology, [1] as it is the simplest model that provides a reasonably good account of: the existence and structure of the cosmic microwave background;
where is the Einstein tensor, is the cosmological constant (sometimes taken to be zero for simplicity), is the metric tensor, is a constant, and is the stress–energy tensor. The Einstein field equations relate the Einstein tensor to the stress–energy tensor, which represents the distribution of energy, momentum and stress in the spacetime ...
The cosmological principle implies that the metric of the universe must be of the form = where ds 3 2 is a three-dimensional metric that must be one of (a) flat space, (b) a sphere of constant positive curvature or (c) a hyperbolic space with constant negative curvature. This metric is called the Friedmann–Lemaître–Robertson–Walker (FLRW ...
In modern physical cosmology, the cosmological principle is the notion that the spatial distribution of matter in the universe is uniformly isotropic and homogeneous when viewed on a large enough scale, since the forces are expected to act equally throughout the universe on a large scale, and should, therefore, produce no observable inequalities in the large-scale structuring over the course ...
The simplest explanation of dark energy is the cosmological constant (the 'Lambda' in Lambda-CDM). This is a simple constant added to the Einstein field equations to provide a repulsive force. Thus far observations are fully consistent with the cosmological constant, but leave room for a plethora of alternatives, e.g.: