Astrophysics

Cosmology

Critical Density

From the Einstein-de
Sitter cosmological model, the critical density of the universe
(the density required for the universe
to be closed to that expansion stops asymptotically at
infinite time) is

where H is the Hubble
constant and G is the gravitational
constant.

The quantity is defined as

so a closed universe
satisfies .

Dicke
Paradox

© Eric W. Weisstein