Gravitational repulsion of spherical domain walls

We consider the disagreements in gravitational properties of planar and spherical domain walls (bubbles). We argue that if the spherical domain walls are described by the same equation of state as the planar walls are, then they also exhibit gravitational repulsion just as the planar walls are assumed to do. In the thin-wall approximation we show the existence of the solution of Einstein equations with negative gravitational mass of bubbles and the reversed direction of time flow on the shell. The equilibrium radius and critical mass of such objects are found for realistic models.