Scalar–vector–tensor decomposition
In cosmological perturbation theory, the scalar–vector–tensor decomposition is a decomposition of the most general linearized perturbations of the Friedmann–Lemaître–Robertson–Walker metric into components according to their transformations under spatial rotations. It was first discovered by E. M. Lifshitz in 1946.
Source: Wikipedia — Scalar–vector–tensor decomposition (CC BY-SA 4.0)