Super-energy tensor for space-times with vanishing scalar curvature.

Constructs a four-index tensor with terms both quadratic in the Riemann tensor and linear in its second derivatives, which has zero divergence for space-times with vanishing scalar curvature. Long history of the investigation of conservation laws in general relativity; Friedman-Lemaitre-Robertson-Walker models with an energy-momentum content of incoherent radiation.