Congruence (general relativity)
= Congruence
{disambiguate=general relativity}
{wiki}
= Congruence of curves in general relativity
{synonym}
A congruence in <general relativity> is a family of curves through an open spacetime region such that each point lies on exactly one member. Its tangent field describes the family locally. A <geodesic congruence> is the special case in which every member is a <geodesic>.