Ad
related to: cosmological constant for dummies 2 free
Search results
Results From The WOW.Com Content Network
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 ...
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.
For many years the cosmological constant was almost universally assumed to be zero. More recent astronomical observations have shown an accelerating expansion of the universe, and to explain this a positive value of Λ is needed. [18] [19] The effect of the cosmological constant is negligible at the scale of a galaxy or smaller.
Each point in space makes a contribution of E = ħω / 2 , resulting in a calculation of infinite zero-point energy in any finite volume; this is one reason renormalization is needed to make sense of quantum field theories. In cosmology, the vacuum energy is one possible explanation for the cosmological constant [18] and the source of ...
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;
A free (=) scalar field has =, and one with vanishing kinetic energy is equivalent to a cosmological constant: =. Any equation of state in between, but not crossing the w = − 1 {\displaystyle w=-1} barrier known as the Phantom Divide Line (PDL), [ 2 ] is achievable, which makes scalar fields useful models for many phenomena in cosmology.
Moreover, it is the unique dimensionality that can afford a "stable" gas sphere with a "positive" cosmological constant. However, a self-gravitating gas cannot be stably bound if the mass sphere is larger than ~10 21 solar masses, due to the small positivity of the cosmological constant observed. [57]
The isometry group of de Sitter space is the Lorentz group O(1, n).The metric therefore then has n(n + 1)/2 independent Killing vector fields and is maximally symmetric. Every maximally symmetric space has constant curvature.