What would it mean to apply quantum theory without restriction to the whole universe? What then does realism about the quantum state imply? This book brings together an illustrious team of philosophers and physicists to debate this question. All the contributors agree on realism and on the need, or the aspiration, for a theory that unites micro- and macroworlds. But they disagree on what this implies. Some argue that if the Schrödinger equation has unrestricted application and if the quantum state is taken to be something physically real then this universe emerges from the quantum state are compromised; the concept of probability itself is in question. There are realist alternatives to many worlds theory, among them theories that leave the Schrödinger equation unchanged. Twenty original essays, accompanied by commentaries and discussions, examine these claims and counterclaims in depth. They are organized according to questions of ontology alternatives to many worlds

Simon Saunders is Professor of Philosophy at the University of Oxford.
Jon Barrett is a Research Fellow in the Physics department at the University of Bristol
Adrian Kent is a Reader in Quantum Physics at the University of Cambridge
David Wallace is a lecturer in Philosophy of Physics at the University of Oxford