Microphysical irreversibility in quantum mechanics (Q1372475)

The authors are exclusively concerned with intrinsic irreversibility in quantum mechanics as opposed to extrinsic irreversibility, which manifests itself in a combined system \(S\otimes R\), where \(S\) does not change \(R\) but \(R\) changes \(S\). In addition to the usual interpretation of quantum mechanics, the authors make more precise and distinct separation between the state and the observable. The mathematical tool for this irreversibility is the rigged Hilbert space. The physical basis is found in the distinct initial and boundary conditions for the states and observables, which is formulated in terms of an arrow of time. The principal objects of this theory are resonances which are defined by resonance poles of the \(S\)-matrix and described by generalized eigenvectors which are Jordan vectors of higher degree.