  It is taken into account that not the Ricci tensor ${R_{il}}$ (Einstein
equation), but the Riemann tensor ${R_{iklm}}$ provides the most general
description of the space geometry. If ${{R_{il}}=0}$ (the space empty with
matter, but it can be occupied by gravitational waves) then
${{R_{iklm}}={C_{iklm}}} $ . The tensor ${C_{iklm}}$ is the Weyl tensor, which
disappears by conversion:${{R_{il}}={g^{km}}{R_{iklm}}}$ and we lose all
information about the space structure, which is described by ${C_{iklm}}$ .The
symmetry of ${R_{il}}$ provides the existents of gravitational waves with the
spin s=2. We show that ${C_{iklm}}$ describes gravitational waves with s=1.
Such gravitational waves can be created in inhomogeneous media, where the
selected directions are determined by derivates of the energy-momentum tensor
${T^m}_{i,k}$ of matter. It is taken into account that gravitation is described
not only by the metric tensor $g^{ik} = (1/2)(\gamma^i \gamma^k + \gamma^k
\gamma^i)$, but also by the anti-symmetric tensor $\sigma^{ik} =
(i/2)({\gamma^i}{\gamma^k} - {\gamma^k}{\gamma^i})$, where ${\gamma^k}(x)$ are
Clifford matrices. We show that the tensor ${K_{ik}} = (1/4){\sigma^{lm}}
{R_{iklm}}$, is the anty-simmetric analog to the Ricci tensor. The ${K_{lm}}$
describes various kinds of space metrics, not described by the Ricci tensor. It
includes the Weyl tensor ${C_{iklm}}$, because $\sigma^{lm} {C_{lmik}}$ is not
zero.
