Online research in philosophy

The simplest case of quantum field theory on curved spacetime-that of the Klein-Gordon field on a globally hyperbolic spacetime-reveals a dilemma: In generic circumstances, either there is no dynamics for this quantum field, or else there is a dynamics that is not unitarily implementable. We do not try to resolve the dilemma here, but endeavour to spell out the consequences of seizing one or the other horn of the dilemma.

It is widely accepted that consciousness or, in other words, mental activity is in some way correlated to the behavior of the brain or, in other words, material brain activity. Since quantum theory is the most fundamental theory of matter that is currently available, it is a legitimate question to ask whether quantum theory can help us to understand consciousness. Several approaches answering this question a?rmatively, proposed in recent decades, will be surveyed. It will be pointed out that they make di?erent epistemological assumptions, refer to di?erent neurophysiological levels of description, and adopt quantum theory in di?erent ways. For each of the approaches discussed, these imply both..

A human brain operates as a pattern of switching. An abstract definition of a quantum mechanical switch is given which allows for the continual random fluctuations in the warm wet environment of the brain. Among several switch-like entities in the brain, we choose to focus on the sodium channel proteins. After explaining what these are, we analyse the ways in which our definition of a quantum switch can be satisfied by portions of such proteins. We calculate the perturbing effects of normal variations in temperature and electric field on the quantum state of such a portion. These are shown to be acceptable within the fluctuations allowed for by our definition. Information processing and unpredictability in the brain are discussed. The ultimate goal underlying the paper is an analysis of quantum measurement theory based on an abstract definition of the physical manifestations of consciousness. The paper is written for physicists with no prior knowledge of neurophysiology, but enough introductory material has also been included to allow neurophysiologists with no prior knowledge of quantum mechanics to follow the central arguments.

The book is the first to give a systematic account, founded in fundamental quantum physical principles, of how the brain functions as a unified system.

Quantum mechanics unites epistemology and ontology: it brings human knowledge explicitly into physical theory, and ties this knowledge into brain dynamics in a causally efficacious way. This development in science provides the basis for a natural resolution of the dualist functionalist controversy, which arises within the classical approach to the mind brain system from the fact that the phenomenal aspects are not derivable from the principles of classical mechanics. A conceptually simple causal quantum mechanical theory of the mind/brain is described, and used to examine the necessity and function of consciousness in brain process.

We review the dissipative quantum model of the brain and present recent developments related to the role of entanglement, quantum noise and chaos in the model.

This article arises from the remarkably multi-faceted book Brain and Being edited by Gordon Globus and others, hereafter referred to as B&B. It raises questions (though not unusually, few answers) about several related areas: the way in which quantum theory might endow the physical matter of the brain with surprising, though still essentially classical, properties; the possibility that quantum field theory might shed a wholly new light on aspects of consciousness, in both the subjective and neurological approaches; and, at the most speculative, the suggestion that the nature of being, as disclosed subjectively, can be understood in the light of one or other of the interpretations of quantum theory. I will consider these in turn.