Using string field theory, we argue that the tachyon potential on a D-brane
anti-D-brane system in type II string theory in arbitrary background has a
universal form, independent of the boundary conformal field theory describing
the brane. This implies that if at the minimum of the tachyon potential the
total energy of the brane antibrane system vanishes in a particular background,
then it vanishes in any other background. Similar result holds for the tachyon
potential of the non-BPS D-branes of type II string theory, and the D-branes of
bosonic string theory.Comment: LaTeX file, epsf, 1 figure, 21 pages, references adde
