### Friedmann model

**(Friedmann universe, Friedmann-Lemaitre universe)**
(type of model of universe incorporating general relativity)

A **Friedmann model** (**Friedmann universe** or **Friedmann-Lemaitre universe**)
is a type of model of the universe incorporating general relativity (GR).
Specific instances vary on the amount of mass, whether
there is sufficient to reach or exceed the critical density.
An instance exactly at the critical density is termed an
Einstein-de Sitter model. Friedmann models are based the
**Friedmann equations**, a set of equations compatible with GR worked
out by Alexander Friedmann. Georges Lemaitre subsequently independently
worked out the same model.

(*physics,model,cosmology*)
**Further reading:**

http://en.wikipedia.org/wiki/Friedmann_equations

https://astronomy.swin.edu.au/cosmos/F/Friedmann-Lemaitre+Universe

**Referenced by pages:**

critical density (ρ_{c})

Einstein-de Sitter model

redshift-angular size relation

scale factor (a)

Index