ABSTRACT
The shell model Hamiltonian is invariant under spatial rotations. This fact has profound implications for its eigenstates. Other physical operators which are not invariant may have well defined transformation properties under rotations. Much of the following is related to the behavior of various physical entities, operators as well as wave functions, under rotations in three-dimensional space. In the following pages a simple introduction to this subject is presented. First, single particle states and operators will be discussed. Subsequent sections will deal with transformation properties of more general systems of several nucleons.
