An Etymological Dictionary of Astronomy and Astrophysics

A parameter occurring in the → Friedmann equations of
→ general relativity describing the geometry of → space-time. A spatially → open Universe is defined by k = -1, a → closed Universe by k = + 1 and a → flat Universe by k = 0. See also the → Robertson-Walker metric. See also → curvature of space-time.

See also: → curvature; → parameter.