Expansion scalar
= Expansion scalar
{title2=$\theta$}
The expansion scalar of a unit timelike congruence with tangent $u^a$ is $\theta=\nabla_au^a$. It gives the fractional rate of change of an infinitesimal comoving spatial volume.
= Expansion scalar
{title2=$\theta$}
The expansion scalar of a unit timelike congruence with tangent $u^a$ is $\theta=\nabla_au^a$. It gives the fractional rate of change of an infinitesimal comoving spatial volume.