  Recently a realization of the four-dimensional gravity on a brane in
five-dimensional spacetime has been discussed. Randall and Sundrum have shown
that the equation for the longitudinal components of the metric fluctuations
admit a normalizable zero mode solution, which has been interpreted as the
localized gravity on the brane. We point out that the equation for the
transverse components of the metric fluctuations has a solutions which is not
localized on the brane. This indicates that probably the effective theory is
unstable or, in other words, actually it is not four-dimensional but
five-dimensional. Perhaps a modification of the proposal by using matter fields
can lead to the trapping of gravity to the brane.
