  We use the model of L. Randall et al to investigate the stability of allowed
quantum field configurations. Firstly, we find that due to the topology of this
5 dimensional model, there are 2 possible configurations of the scalar field,
untwisted and twisted. They give rise to two types of instability. Secondly,
when allowed to interact in the 3-brane, the untwisted field becomes unstable
even if it is at the true vacuum groundstate.This instability in the 4D
submanifold results results from one-loop corrections that arise from coupling
with the twisted field. On the other hand, the twisted field can make the two
3-branes distinguishable by causing an energy difference between them. That is
due to the antiperiodicity of the twisted fields, when rotating with $\pi$ to
go from one 3-brane to the other. The energy difference between the branes
renders the fifth dimension unstable.
