Showing papers on "Quantum geometry published in 1979"
01 Jan 1979
311 citations
TL;DR: In this article, the quantum fluctuations of instantons having arbitrary topological number are studied, and the results show that instantons with arbitrary topology are stable in terms of quantum fluctuations.
67 citations
TL;DR: Party and Freedman as discussed by the authors reviewed the present conceptual basis for quantum mechanics and then described the experiments that have been carried out to test these concepts and the relevant experiments are precision measurements of the predicted eigenvalue spectrum, single-photon interference experiments, successive measurements on eigenstates, measurements of photonphoton 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.
Abstract: Publisher Summary 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 2 π rad. Earlier reviews that summarize some of the information presented here are given by Paty , Freedman and Holt , and Freedman.
44 citations
01 Apr 1979
30 citations
21 citations
TL;DR: The effect of unitary inequivalence of different versions of the formalism of quantum gravity, according to the arbitrary choice of coordinate conditions, does not mean a violation of general covariance but a furcation of a single classical theory into several inequivalent but also generally covariant quantum theories.
Abstract: The effect of unitary inequivalence of different versions of the formalism of quantum gravity, according to the arbitrary choice of coordinate conditions, does not mean a violation of general covariance but a furcation of a single classical theory into several inequivalent, but also generally covariant quantum theories. We choose a version closely analogous to the theory of Proca, with a strong supplementary condition, leading to a quantum gravity with a cosmological term. However, it is only the bare but not necessarily the dressed cosmological term that has to be different from zero. Ordinary theory without the cosmological term may be obtained by renormalization.
11 citations
TL;DR: In this article, it was shown that the collapse of a dust ball of mass M > 10−5 g terminates at a distance of the order of the Planck length.
7 citations
TL;DR: In this paper, a method of calculating the mean energy of a quantum system if the latter is subjected to time periodic perturbations is discussed, including the possibility of determining shapes of spectral lines for an arbitrary distribution of nonperturbed energy levels.
Abstract: Abstract We discuss a method of calculating the mean energy of a quantum system if the latter is subjected to time periodic perturbations. This, e.g., includes the possibility of determining shapes of spectral lines for an arbitrary distribution of nonperturbed energy levels. The method is studied on a system of order 2 whose spectral line is exactly lorentzian. We prove that the next to lowest approximation reproduces this form exactly.
1 citations
TL;DR: In this paper, a 3-metric geodesic equation is proposed to describe the state of a quantum gravitational system. But it does not describe the dynamics of the system.
Abstract: A gravitational-field equation defined in the space of 3-metrics is proposed to describe the state of a quantum gravitational system.