What does realism about the quantum state imply? What follows when quantum theory is applied without restriction, if need be, to the whole universe? These are the questions which an illustrious team of philosophers and physicists debate in this volume. All the contributors are agreed on realism, and on the need, or the aspiration, for a theory that unites micro- and macroworlds, at least in principle. But the further claim argued by some is that if you allow the
Schrödinger equation unrestricted application, supposing the quantum state to be something physically real, then this universe is one of countlessly many others, constantly branching in time, all of
which are real. The result is the many worlds theory, also known as the Everett interpretation of quantum mechanics.Twenty specially written essays, accompanied by commentaries and discussions, examine the question of many worlds in depth. They focus first on the question of ontology and the existence of worlds, then on the interpretation of probability, and finally on alternatives or additions to many worlds. The introduction offers a helpful guide to the arguments for the Everett
interpretation, particularly as they have been formulated in the last two decades.
