Foundations of Physics

Gudder, Stanley

doi: 10.1007/BF01883150pmid: N/A

We first present a realistic framework for quantum probability theory based on the path integral formalism of quantum mechanics and illustrate this framework by constructing a model that describes a quantum particle evolving in a discrete space-time lattice. We then present a finite model for describing the internal dynamics of “elementary particles” and show that this model gives the standard particle classification scheme and successfully predicts particle masses.

Ludwig, G.

doi: 10.1007/BF01883151pmid: N/A

The reality of atoms can be deduced from the reality of the devices by which the atoms are prepared and registered. A new, most general definition of the concept of “physical object” is given. The objects must not be classical; nevertheless they can be described objectively. Atoms are not such objects.

Klüppel, M.; Neumann, H.

doi: 10.1007/BF01883152pmid: N/A

An axiomatic foundation of a quantum theory for microsystems in the presence of external fields is developed. The space-time structure is introduced by considering the invariance of the theory under a kinematic invariance group. The formalism is illustrated by the example of charged particles in electromagnetic potentials. In the example, gauge invariance is discussed.

Pavičić, Mladen

doi: 10.1007/BF01883153pmid: N/A

Unified quantum logic based on unified operations of implication is formulated as an axiomatic calculus. Soundness and completeness are demonstrated using standard algebraic techniques. An embedding of quantum logic into a new modal system is carried out and discussed.

Piron, Constantin

doi: 10.1007/BF01883154pmid: N/A

In this dialogue we explain why nonrelativistic and relativistic quantum mechanics are basically the same and how the Lorentz group operates canonically only on the dynamics.

Quadt, Ralf

doi: 10.1007/BF01883155pmid: N/A

It is shown in this paper that a classical way of speaking about the past can be rejected when quantum systems without superselection rules are considered. To show this, use is made of a formal quantum language. The noncontextuality of quantum measurements is a presupposition of the quantum language. In addition, it is shown that introspective measurements, in contrast to the claims of Albert et al., do not violate the noncontextuality, and hence the result of rejecting the classical way of speaking remains still applicable to introspective measurements.

Reiter, H.; Thirring, W.

doi: 10.1007/BF01883156pmid: N/A

Common eigenfunctions of nontrivial projectors of x and p are constructed.

Ristig, M.

doi: 10.1007/BF01883157pmid: N/A

We outline the principal features of Bose and Fermi fluids that are revealed in particle scattering experiments at high momentum transfer. In this regime, the dynamic structure function is determined by the dominant influence of correlations which are embodied in the static one- and two-body density matrices characterizing a strongly correlated system. We analyze the general structure of these fundamental quantities and of the associated momentum distributions that enter as input quantities for determining the dynamical response. We discuss their physical interpretation and their interrelationships. We further describe the main features of advanced many-body methods, which begin on a nonperturbative basis. They permit a formal and numerical evaluation of various quantities that characterize the structure of the density matrices and therewith of quantum fluids and solids.