  It is well known that the unboundedness of operators in Hilbert space entails
domain troubles. It is also well known that most domain troubles can be
surmounted by extending the Hilbert space to a rigged Hilbert space. In this
note, we point out another of such troubles, namely the correspondence between
the Schrodinger and the Heisenberg pictures for unbounded operators, and sketch
the solution of this problem within the rigged Hilbert space.
