FATE OF INITIAL PERTURBATION IN THE JORDAN-BRANS-DICKE GRAVITY

During the epoch of extended inflation the variation of the gravitational constant is crucial to facilitate the percolation of a true vacuum. In a relevant gravity theory we analyze the problem of evolving instability against linear perturbation in a static spherically symmetric background by constructing an exact solution to the Cauchy problem. Our analysis greatly affects primordial black-hole formation and gravitational-wave emission during extended inflation.