Astrophysics (Index)About

Einstein-de Sitter model

(Einstein-de Sitter universe)
(universe tuned to the smallest expansion that continues forever)

The Einstein-de Sitter model of the universe (i.e., Einstein-de Sitter universe) posits a universe constrained by gravity according to general relativity (GR), and expanding just fast enough that it will continue expanding to infinity, and no faster than that. (Analogous is a rocket launched at exactly escape velocity and no more.) It is a particular Friedmann model for a flat matter-only universe, i.e., at the critical density. Friedmann models (or Friedmann universes) are models of the universe adhering to the Friedmann equations, a solution to Einstein's general relativity equations. The Einstein-de Sitter model is, in effect, an approximation of modern models such as the Lambda-CDM model, and before evidence of dark energy was discovered, observation of the real universe supported the Einstein-de Sitter model and it was considered a realistic model.

An earlier model, termed a de Sitter universe, represents a theoretical universe simplified in that the effects of matter are ignored, but includes cosmological constant (matching Einstein's initially-published GR equations). It includes expansion of the universe and was early among models that did so.


(physics,model,cosmology)
Further reading:
https://en.wikipedia.org/wiki/Einstein-de_Sitter_universe
https://en.wikipedia.org/wiki/De_Sitter_universe
https://dictionary.obspm.fr/index.php?showAll=1&formSearchTextfield=Einstein-de+Sitter+Universe
https://scienceworld.wolfram.com/physics/Einstein-deSitterCosmologicalModel.html
https://www.britannica.com/science/cosmology-astronomy/The-Einstein-de-Sitter-universe
https://ned.ipac.caltech.edu/level5/Watson/Watson2_4_1.html
https://www.oxfordreference.com/view/10.1093/oi/authority.20110803095744723
https://ui.adsabs.harvard.edu/abs/2021EPJH...46....4O/abstract

Referenced by pages:
anti-de Sitter space (AdS)
critical density (ρc)
density parameter
Friedmann model

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