Radiation boundary condition for linearized gravity
= Radiation boundary condition for linearized gravity
The retarded source solution of the <Linearized Einstein equations> is selected by excluding added incoming or freely specified homogeneous <gravitational waves>. A homogeneous wave can satisfy <Lorenz gauge in linearized gravity> while having no source <mass quadrupole moment>. Thus a formula for the retarded source field is not an identity for every solution of the sourced wave equation.