  ``Dimension bubbles'' of the type previously studied by Blau and Guendelman
[S.K. Blau and E.I. Guendelman, Phys. Rev. D40, 1909 (1989)], which effectively
enclose a region of 5d spacetime and are surrounded by a region of 4d
spacetime, can arise in a 5d theory with a compact extra dimension that is
dimensionally reduced to give an effective 4d theory. These bubbles with thin
domain walls can be stabilized against total collapse in a rather natural way
by a scalar field which, as in the case with ``ordinary'' nontopological
solitons, traps light scalar particles inside the bubble.
