  Various subtleties and problems associated with nonrelativistic (NR)
reduction of a scalar field theory to the Schroedinger theory are discussed.
Contrary to the usual approaches that discuss the mapping among the equations
of motion or the actions, we highlight the mapping among the space time
generators. Using a null reduction we show the embedding of the conformal
generators of the Schroedinger theory to that of a complex scalar theory in one
higher dimension. As applications we reveal the conformal symmetry in
hydrodynamics and the obtention of NR diffeomorphism symmetry from the
relativistic one. A geometrical connection based on Horava-Lifshitz and
Newton-Cartan spacetime is discussed.
