Direct recovery of ammonia as sulphate, without distillation: W. Strommenger. ( Stahl und Eisen, xli 1694.)

Abstract

Quantum mechanics is the theory used to describe microscopic systems such as atoms, molecules, and elementary particles. It grew early in this century from a synthesis of Planck's introduction of the elementary quantum of action to understand the observed spectrum for blackbody radiation, Einstein's use of the quantum of action to explain the photoelectric effect, and Bohr's combination of the planetary model of the atom and the quantum of action to create a description of the hydrogen atom with a distinct set of stationary energy states. The present form of the nonrelativistic theory was developed independently by Schrodinger through the use of a wave equation that was motivated by work by de Broglie and by Heisenberg through an algebraic analysis based on a calculus of observables and motivated by dispersion theory relationships. This chapter first reviews the present conceptual basis for quantum mechanics and then describes the experiments that have been carried out to test these concepts. The relevant experiments are precision measurements of the predicted eigenvalue spectrum, single-photon interference experiments, successive measurements on eigenstates, measurements of photon-photon and spin correlations as a test of Bell's inequality, and the observation of the sign change for the rotation of the neutron through 2π rad. Earlier reviews that summarize some of the information presented here are given by Paty, Freedman and Holt, and Freedman.