Gravitational and electromagnetic wave flux compared and contrasted

The ratio of Poynting flux to density of electromagnetic energy in the generic case tells the direction and magnitude of the boost required to reduce the flux to zero (parallel $\overrightarrow{\mathrm{E}}$ and $\overrightarrow{\mathrm{B}}$); but the ratio of flux to density of gravitational superenergy in the generic case gives the wrong direction and magnitude for the boost required to reduce that flux to zero (3 × 3 symmetric traceless tensors $\mathcal{E}$ and $\mathcal{B}$ simultaneously diagonalizable). This difference is established and illustrated by an example, and made reasonable by comparing and contrasting gravitation and electromagnetism.