  A new moving domain wall solution is obtained for a flat 3-universe. This
consists of a bulk metric depending on both time and the extra coordinate, plus
a dynamically interacting domain wall, admitted by the metric and inhabited by
the three-universe. The matter contents are cosmological constants on the
domain wall and the bulk. The bulk space is shown to be (A)dS_(5). A remarkable
fact concerning the three-universe is that its scale factor never vanishes,
even though the corresponding scale factor of the bulk metric vanishes. The
inclusion of a bulk scalar field is discussed, neglecting back-reaction. Its
normalizability and the existence of a positive frequency or adiabatic bulk
vacuum are shown.
