Spherically symmetric inflation

It is shown in this letter that in the framework of an inhomogeneous geometry and a massive non-self-interacting scalar field with spherical symmetry, one needs a homogeneous patch bigger than a dizain of horizons in order to start inflation. The results are completely independent of initial conditions on the spatial distribution of the scalar field. The initial condition on the metric parameters are also justified. This is a generalization of the results obtained by E. Calzetta and M. Sakellariadou [1]: Phys. Rev. D 45, 2802 (1992), showing that their conclusions are rather robust.