 The models employed here are a bit simplistic compared to the experimental situation in a laboratory. However, extending them to something more realistic poses difficulties no worse than those encountered when introducing quasiclassical descriptions. Thus, rather than a pure initial state \(\ket{m_0}\) for the apparatus it is more realistic to use a macroscopic projector of the type mentioned in   section 6, or else an initial density operator. These changes present no difficulty in principle, and some of them are discussed in Ch. 17 of Griffiths (2002a). The role of decoherence is to allow a consistent quasiclassical description, as noted in  section 6. By itself decoherence does not resolve either of the measurement problems; see, e.g., Adler (2003).