The Quantum Theory of Measurement The amazing accuracy in verifying quantum effects experimentally has recently renewed interest in quantum mechanical measurement theory. In this book the authors give within the Hilbert space formulation of quantum mechanics a systematic exposition of the quantum theory of measurement. Their approach includes the concepts of unsharp objectification and of nonunitary transformations which are needed for a unifying description of various detailed investigations. The book which may be regarded as a first step toward a textbook on the problem of measurements addresses advanced students and researchers in physics and philosophy of science