The Collapse of the Wave Function and the Einstein Gravitation.

Navneet Bhurani

Angelo Bassi

Gravitational decoherence and gravitational wave function collapse are presented as two related but conceptually distinct ideas. Gravitational decoherence measures the effect of gravitational perturbations on the evolution of quantum systems, in particular their progressive lack of coherence. Gravitational wave function collapse starts with the assumption that the Schr¨odinger equation is not entirely right, and must be supplemented with extra terms, which cause the (random) collapse of the wave function; the collapse is then linked to gravity. Some of the most popular models are reviewed, with an emphasis on their conceptual status, stage of development, and open questions.

Ronald F. Peierls

John R. Ellis, Subhendra Mohanty, D.V. Nanopoulos

Lajos Diósi

We give a twist to the assumption – discussed in various earlier works – that gravity plays a role in the collapse of the wave function. This time we discuss the contrary assumption that the collapse of the wave function plays a role in the emergence of the gravitational field. We start from the mathematical framework of a particular Newtonian gravitational collapse theory proposed by the author longtime ago, and we reconciliate it with the classical equivalence principle.

Richard Joseph Oldani

The title has changed because the objective has also changed. The purpose of earlier versions was to clarify Einstein’s intent when he formulated his quantum theory of radiation: why choose statistical methods to derive Planck’s law, why emphasize momentum, and why are both important to a “final theory”. We find that Einstein’s methods have the common property that they are formulated in continuous space and time. It means that the problem of the quantum-classical divide does not exist in any of his theories, and that his results are fully consistent in the presence of non-linear gravitational fields. To see if his unconventional methods can provide the insights necessary to resolve the long-standing problem of wave function collapse we will compare how the two versions interpret causality. We show that Gödel’s incompleteness theorem is key to a reinterpretation of wave function collapse.