On the use of classical configurations as subcritical bubbles

The role of classical configuration as subcritical bubbles in the physics of the early universe is analyzed. It is shown that the subcritical bubbles in the scalar background can only be viewed classical objects, i.e. they obey the classical equations of motion, if their amplitude is small, so that the change of the number of quanta is not too rapid. Also it is required that the number of quanta is large enough. In particular analyses with Gaussian bubbles of the size of the size of the correlation length and amplitude of the non-trivial minimum of the scalar potential seem not to be generally valid but should be done with more care.