Collapse of the wave function : models ontology origin and implications This is the first single volume about the collapse theories of quantum mechanics which is becoming a very active field of research in both physics and philosophy. In standard quantum mechanics it is postulated that when the wave function of a quantum system is measured it no longer follows the Schrödinger equation but instantaneously and randomly collapses to one of the wave functions that correspond to definite measurement results. However why and how a definite measurement result appears is unknown. A promising solution to this problem are collapse theories in which the collapse of the wave function is spontaneous and dynamical. Chapters written by distinguished physicists and philosophers of physics discuss the origin and implications of wave function collapse the controversies around collapse models and their ontologies and new arguments for the reality of wave function collapse. This is an invaluable resource for students and researchers interested in the philosophy of physics and foundations of quantum mechanics. Shan Gao is Professor of Philosophy at the Research Center for Philosophy of Science and Technology at Shanxi University. He is the founder and managing editor of the International Journal of Quantum Foundations and is the author of several books including the recent monograph The Meaning of the Wave Function: In Search of the Ontology of Quantum Mechanics (Cambridge University Press 2017). His research focuses on the philosophy of physics and foundations of quantum mechanics. He is also interested in the philosophy of mind and the philosophy of science How to teach and think about spontaneous wave function collapse theories: not like before Lajos Diósi What really matters in Hilbert space stochastic processes Giancarlo Ghirardi Oreste Nicrosini and Alberto Rimini Dynamical collapse for photons Philip Pearle Quantum state reduction Dorje C. Brody and Lane P. Hughston Collapse models and spacetime symmetries Daniel J. Bedingham Ontology for collapse theories Wayne C. Myrvold Properties and the born rule in GRW theory Roman Frigg Paradoxes and primitive ontology in collapse theories of quantum mechanics Roderich Tumulka On the status of primitive ontology Peter J. Lewis Collapse or no collapse What is the best ontology of quantum mechanics in the primitive ontology framework Michael Esfeld Quantum state reduction via gravity and possible tests using Bose Einstein condensates Ivette Fuentes and Roger Penrose Collapse. What else Nicolas Gisin Three arguments for the reality of wave function collapse Shan Gao Could inelastic interactions induce quantum probabilistic transitions Nicholas Maxwell How the Schrödinger equation would predict collapse: an explicit mechanism Roland Omnes Wave function collapse non locality and space time structure Tejinder P. Singh The weight of collapse: dynamical reduction models in general relativistic contexts Elias Okon and Daniel Sudarsky