We describe mirror symmetry in N = 2 superconformal field theories in
terms of a dynamical topology changing process of the principal fiber
bundle associated with a topological membrane. We show that the topolo
gical symmetries of Calabi-Yau sigma-models can be obtained from discr
ete geometric transformations of compact Chern-Simons gauge theory cou
pled to charged matter fields. We demonstrate that the appearence of m
agnetic monopole-instantons, which interpolate between topologically i
nequivalent vacua of the gauge theory, implies that the discrete symme
try group of the worldsheet theory is realized kinematically in three
dimensions as the magnetic flux symmetry group. From this we construct
the mirror map and show that it corresponds to the interchange of top
ologically non-trivial matter field and gauge degrees of freedom. We a
lso apply the mirror transformation to the mean field theory of the qu
antum Hall effect. We show that it maps the Jain hierarchy into a new
hierarchy of states in which the lowest composite fermions have the sa
me filling fractions. (C) 1998 Academic Press.