Gravitational field of vacuum domain walls and strings

The gravitational properties of vacuum domain walls and strings are studied in the linear approximation of general relativity. These properties are shown to be very different from those of regular massive planes and rods. It is argued that the domain walls are gravitationally unstable and collapse at a certain time $\sim t_c$ after their creation. If the vacuum walls ever existed, they must have disappeared at $t<\mathrm{}{t}_c$.