Interpreting Quantum Theories

by Laura Ruetsche

Traditionally, philosophers of quantum mechanics have addressed exceedingly simple a pair of electrons in an entangled state, or an atom and a cat in Dr. Schrodinger's diabolical device. But recently, much more complicated systems, such as quantum fields and the infinite systems at the thermodynamic limit of quantum statistical mechanics, have attracted, and repaid, philosophical attention. Interpreting Quantum Theories has three entangled aims. The first is to guide those familiar with the philosophy of ordinary QM into the philosophy of 'QM infinity', by presenting accessible introductions to relevant technical notions and the foundational questions they frame. The second aim is to develop and defend answers to some of those questions. Does quantum field theory demand or deserve a particle ontology? How (if at all) are different states of broken symmetry different? And what is the proper role of idealizations in working physics? The third aim is to highlight ties
between the foundational investigation of QM infinity and philosophy more broadly construed, in particular by using the interpretive problems discussed to motivate new ways to think about the nature of physical possibility and the problem of scientific realism.

Genres: Physics, Philosophy, Science, Quantum Mechanics

398 pages, Hardcover

First published July 21, 2011

Reviews

[Mark Moon · Rating 5 out of 5]

Rather than rehashing the old issues about interpreting quantum theories with finitely many degrees of freedom (many worlds, hidden variables, spontaneous collapse, etc.), Ruetsche focuses on the rather different (and less ontological) matters that arise in interpreting quantum theories with infinitely many degrees of freedom (which she collectively dubs "QM∞"). These issues often revolve around the failure of von Neumann's uniqueness theorem: for quantum systems with infinitely many degrees of freedom, the algebra of canonical observables will typically have infinitely many (non-unitarily-equivalent) representations on a Hilbert space. Philosophical (not to mention technical) problems related to this non-uniqueness pervade quantum field theory quantum statistical mechanics. Ruetsche's view is that no individual "pristine interpretation" (the sort of interpretation that specifies exactly which worlds are possible for a given theory) is capable of making sense of every application of QM∞. She proposes the "coalescence approach", according to which "there can be an a posteriori, even a pragmatic, dimension to content specification, and that physical possibility is not monolithic but kaleidoscopic.".

[Nitica · Rating 5 out of 5]

A good starting point for someone looking for an introduction to Algebraic QFT (Quantum Field Theory) without being overwhelmed by mathematical detail and wanting to see the big picture issues that interpretations of QFT face, with few approaches of how to go about them. Also includes discussion on infinite dimensional quantum systems found in Statistical mechanics.

[Fuzzball Baggins · Rating 1 out of 5]

Every second word was jargon. Obscure theories were constantly referenced by name with no explanations for what they meant. This book was completely uninterpretable.