The Quantum Measurement Problem and the Possible Role of the Gravitational Field

Pedro F. Gonzalez-Diaz

J. Anandan

The quantum measurement problem and various unsuccessful attempts to resolve it are reviewed. A suggestion by Diosi and Penrose for the half life of the quantum superposition of two Newtonian gravitational fields is generalized to an arbitrary quantum superposition of relativistic, but weak, gravitational fields. The nature of the ``collapse'' process of the wave function is examined.

Marco Di Mauro, Salvatore Esposito, Adele Naddeo

The broad debate on foundational issues in quantum mechanics, which took place at the famous 1957 Chapel Hill conference on \textit{The Role of Gravitation in Physics}, is here critically analyzed with an emphasis on Richard Feynman's contributions. One of the most debated questions at Chapel Hill was whether the gravitational field had to be quantized and its possible role in wave function collapse. Feynman's arguments in favor of the quantization of the gravitational field, based essentially on a series of gedanken experiments, are here discussed. Then the related problem of the wave function collapse, for which Feynman hints to decoherence as a possible solution, is discussed. Finally, another topic is analyzed, concerning the role of the observer in a closed Universe. In this respect, Feynman's many-worlds characterization of Everett's approach at Chapel Hill is discussed, together with later contributions of his, including a kind of Schrödinger's cat paradox, which are scattered throughout the 1962-63 Lectures on Gravitation. Philosophical implications of Feynman's ideas in relation to foundational issues are also discussed.

JOHN ARCHIBALD WHEELER

Lajos Diósi

J. Anandan

Abstract Department of Physics and Astronomy University of South Carolina, Columbia, SC 20208, USA [AF] Two of the most important unsolved problems in theoretical physics are the problem of quantizing gravitation and the measurement problem in quantum theory. It is possible that the solution of each one needs the other. Since we have successful quantum theories of electroweak, and strong interactions, the solution to the problem of the collapse of the wave function, known as the measurement problem, may lie in the yet unknown quantum theory of the remaining interaction, namely quantum gravity. On the other hand, the numerous unsuccessful attempts to construct a quantum theory of gravity for more than six decades on the assumption that the present linear quantum theory is correct suggests that perhaps not only general relativity but also quantum theory should be modified in order to construct of satisfactory quantum theory of gravity.