The only observational quantity which quantum mechanics needs to address islocation. The typical primitive observation on a microsystem (e.g., photon) isdetection at alocation (e.g., by a photomultiplier “looking at” a grating). To analyze an experiment, (a) form a conceptual ensemble of replicas of it, (b) assign a wave function (in “position representation”) to its initial condition, (c) evolve the wave function by the Schrödinger equation (known, once and for all, as a function of the system's composition), (d) compute the probability (...) for particle detection at various times and places. The initial wave function is chosen on the basis of experience with such treatments. Key experiments are thus treated: (i) time-of-flight, (ii) Stern-Gerlach, (iii) Franck-Hertz, (iv) photon recoil, (v) photoionization. Quantum states, dynamical variables, and measurements, and the usual postulates about them, are superfluous. The explicit treatments are nonrelativistic; the existence of relativistic generalizations is left open. (shrink)

The formula for the differential scattering cross section in quantum mechanics is derived without the usual assumption that the square of the ψ-function is a position probability density for particles. It is argued that position, like time, may be basically a macroscopic parameter rather than a random variable for microparticles.

The general properties of signals permit a nonaxiomatic reconstruction of the quantum “probability” formalism independent of the standard Copenhagen interpretation of quantum mechanics. Performance standards are specified for candidate clock, signaller, and reflector devices, and it is shown that the resulting formalism forces identification of a “probability”- or “intensity”-like structure as the absolute square of an amplitude, the relative phases of amplitudes appearing explicitly in the “probability” composition law. Inequalities are produced which on one interpretation reduce to the Heisenberg relations, (...) but it is pointed out that this reconstruction disqualifies position as an observable property of a signal. (shrink)