Lecture on the Physics of Consciousness

Edited for Internet by Jack Sarfatti

Stapp's paper opposes the view represented by Bill Calvin, for example in http://www.well.com/www/wcalvin/

February 8,1995, LBL-36574

Why Classical Mechanics Cannot Naturally Accommodate Consciousness

But Quantum Mechanics Can.

PART I

Henry P. Stapp

Theoretical Physics Group
Lawrence Berkeley Laboratory
Berkeley, California 94720

Abstract

It is argued on the basis of certain mathematical characteristics that classical mechanics is not constitutionally suited to accommodate consciousness, whereas quantum mechanics is. These mathematical characteristics pertain to the nature of the information represented in the state of the brain, and the way this information enters into the dynamics.

Prepared for a Special Issue of "Psyche"

*This work was supported by the Director, Office of Energy Research, Office of High Energy and Nuclear Physics, Division of High Energy Physics of the U. S. Department of Energy under Contract DE-AC03-76SF00098.

I. Introduction

Classical mechanics arose from the banishment of consciousness from our conception of the physical universe. Hence it should not be surprising to find that the readmission of consciousness requires going beyond that theory.

The exclusion of consciousness from the material universe was a hallmark of science for over two centuries. However, the shift, in the 1920's, from classical mechanics to quantum mechanics marked a break with that long tradition: it appeared that the only coherent way to incorporate quantum phenomena into the existing science was to admit also the human observer. (1) Although the orthodox approach of Bohr and the Copenhagen school was epistemological rather than ontological, focusing upon "our knowledge" rather than on any effort to introduce consciousness directly into the dynamics, other thinkers such as John von Neumann (2), Norbert Weiner (3), and J.B.S. Haldane (4) were quick to point out that the quantum mechanical aspects of nature seemed tailor-made for bringing consciousness back into our conception of matter.

This suggestion lay fallow for half a century. But the recent resurgence of interest in the foundations of quantum theory has led increasingly to a focus on the crux of the problem, namely the need to understand the role of consciousness in the unfolding of physical reality. It has become clear that the revolution in our conception of matter wrought by quantum theory has completely altered the complexion of problem of the relationship between mind and matter. Some aspects of this change were discussed already in my recent book (5). Here I intend to describe in more detail the basic differences between classical mechanics and quantum mechanics in the context of the problem of integrating consciousness into our scientific conception of matter, and to argue that certain logical deficiencies in classical mechanics, as a foundation for a coherent theory of the mind/brain, are overcome in a natural and satisfactory way by replacing the classical conception of matter by a quantum conception. Instead of reconciling the disparities between mind and matter by replacing contemporary (folk) psychology by some yet-to- be-discovered future psychology, as has been suggested by the Churchlands, it seems enough to replace classical (folk) mechanics, which is known to be unable to account for the basic physical and chemical process that underlie brain processes, by quantum mechanics, which does adequately describe these processes.

2. Thoughts within the Classical Framework.

Thoughts are fleeting things, and our introspections concerning them are certainly fallible. Yet each one seems to have several components bound together by certain relationships. These components appear, on the basis of psychoneurological data (5), to be associated with neurological activities occurring in different locations in the brain. Hence the question arises: How can neural activities in different locations in the brain be components of a single psychological entity?

The fundamental principle in classical mechanics is that any physical system can be decomposed into a collection of simple independent local elements each of which interacts only with its immediate neighbors. To formalize this idea let us consider a computer model of the brain. According to the ideas of classical physics it should be possible to simulate brain processes by a massive system of parallel computers, one for each point in a fine grid of spacetime points that cover the brain over some period of time. Each individual computer would compute and record the values of the components of the electromagnetic and matter fields at the associated grid point. Each of these computers receives information only from the computers associated with neighboring grid points in its nearly immediate past, and forms the linear combinations of values that are the digital analogs of, say, the first and second derivatives of various field values in its neighborhood, and hence is able to calculate the values corresponding to its own grid point. The complete computation starts at an early time and moves progressively forward in time.

On the basis of this computer model of the evolving brain I shall distinguish the intrinsic description of this computer/brain from an extrinsic description of it.

The intrinsic description consists of the collection of facts represented by the aggregate of the numbers in the various registers of this massive system of parallel computers: each individual fact represented within the intrinsic description is specified by the numbers in the registers in one of these computers, and the full description is simply the conglomeration of these individual facts. This intrinsic description corresponds to the fact that in classical mechanics a complete description of any physical system is supposed to be specified by giving the values of the various fields (e.g., the electric field, the magnetic field, etc.) at each of the relevant spacetime points. Similarly, an intrinsic description of the contents of a television screen might be specified by giving the color and intensity values for each of the individual points (pixels) on the screen, without any interpretive information (It's a picture of Winston Churchill!), or any explicit representation of any relationship that might exist among elements of the intrinsic description (Pixel 1000 has the same values as pixel 1256!). the analogous basic classical-physics description of a steam engine would, similarly, give just the values of the basic fields at each of the relevant spacetime points, with no notice, or explicit representation, of the fact that the system can also be conceived of as composed of various fractional entities, such as pistons and drive shafts etc.: the basic or intrinsic description is the description of what the system is, in terms of its logically independent (according to classical mechanics) local components, not the description of how it might be conceive of by an interpreter, or how it might be described in terms of large functional entities constructed out of the ontologically basic local components.

I distinguish this intrinsic description from an extrinsic description.

An extrinsic description is a description that could be formed in the mind of an external observer that is free to survey in unison, and act upon together, all of the numbers that constitute the intrinsic description, unfettered by the local rules of operation and storage that limit the activities of the computer/brain. This external observer is given not only the capacity to "know"' separately, each of the individual numbers in the intrinsic description; he is given also the ability to know this collection of numbers as a whole, in the sense that he can have a single register that specifies the entire collection of numbers that constitutes the intrinsic description. The entire collection of logically and ontologically independent elements that constitutes the intrinsic description can be represented by a single basic entity in the extrinsic description, and be part of the body of information that this external observer can access directly, without the need for some compositional process in the computer/brain to bring the information together from far-apart locations. In general, collections of independent entities at the level of the intrinsic description can become single entities at the level of an extrinsic description.

The information that is stored in any one of the simple logically independent computers, of which the computer/brain is the simple aggregate, is supposed to be minimal: it is no more than what is needed to compute the local evolution. This is the analog of the condition that holds in classical physics. As the size of the regions into which one divides a physical system tends to zero the dynamically effective information stored in each individual region tends to something small, namely the values of a few fields and their first few derivatives. And these few values are treated in a very simple way. Thus if we take the regions of the computer simulation of the brain that are represented by the individual local computers to be sufficiently small then the information that resides in any one of these local computers appears to be much less than information needed to specify a complex thought, such as the perception of a visual scene: entries from many logically independent (according to classical physics) computers must be combined together to give the information contained in an individual thought, which, however, is a single experiential entity. Thus the thought, considered as a single whole entity, rather than as a collection of independent entities, belongs to the extrinsic level of description, not to the intrinsic level of description.

According to classical mechanics, the description of both the state of a physical system and its dynamics can expressed at the intrinsic level. But then how does one understand the occurrence of experientially whole thoughts? How do extrinsic-level actual entities arise from a dynamics that is completely reducible to an intrinsic-level description?

One possibility is that the intrinsic-level components of a thought are bound together by some integrative process in the mind of a spirit being, i.e., in the mind of a "ghost behind the machine", of an homunculus. This approach shifts the question to an entirely new realm: in place of the physical brain, about which we know a great deal, and our thoughts, about which we have some direct information, one has a new "spirit realm" about which science has little to say. This approach takes us immediately outside the realm of science, as we know it today.

Alternatively, there is the functional approach. The brain can probably be conceived of, in some approximation, in terms of large- scale functional entities that, from a certain global perspective, might seem to be controlling the activity of this brain. However, in the framework of classical mechanics such "entities" play no actual role in determining the course of action taken by the computer/brain: this course of action is completely controlled by local entities and local effects. The apparent efficacy of the large scale "functional entities" is basically an illusion, according to the precepts of classical mechanics, or the dynamics of the computer/brain that simulates it: the dynamical evolution is completely fixed by local considerations without any reference to such global entities.

As an example take a 'belief'. Beliefs certainly influence, in some sense, the activities of the human mind/brain. Hilary Putnam characterized the approach of modern functionalism as the idea that, for example, a belief can be regarded as an entry in a "belief register", or a "belief box", that feeds control information into the computer program that represents the brain process. Such a belief would presumably correspond, physically, to correlations in brain activities that extend over a large part of the brain. Thus it would be an example of a functional entity that a human being might, as a short-hand, imagine to exist as a single whole entity, but that, according to the precepts of classical mechanics, is completely analyzable, fundamentally, into a simple aggregate of elementary and ontologically independent local elements. The notion that such an extrinsic-level functional entity actually is, fundamentally, anything more than a simple aggregate of logically independent local elements is contrary to the precepts of classical mechanics. The grafting of such an actual entity onto classical mechanics amounts to importing into the theory an appendage that is unnecessary, nonefficacious, and fundamentally illusory from the perspective of the dynamical workings of that theory itself.

Since this appendage is causally nonefficacious it has no signature, or sign of existence, within classical physics. The sole reason for adding it to the theory is to account for our direct subjective awareness of it. Logically and rationally it does not fit into the classical theory both because it has no dynamical effects, beyond those due to its local components alone, and because its existence and character contravenes the locality principle that constitutes the foundation of the theory, namely the principle that any physical system is to be conceived of as fundamentally a conglomerate of simple microscopic elements each of which interacts only with its immediate neighbors. Neither the character of the basic description of the brain, within classical mechanics, nor the character of the classical dynamical laws that supposedly govern the brain, provides any basis for considering the brain correlate of a thought to be, at the fundamental as distinguished from functional level, a single whole entity. One may, of course, postulate some extra notion of "emergence". But nature must be able to confer some kind of beingness beyond what is suggested by the precepts of classical mechanics in order to elevate the brain correlate of a belief to the status of an ontological whole.

This problem with `beliefs', and other thoughts, arises from the attempt to understand the connection of thoughts to brains within the framework of classical physics. This problem becomes radically transformed, however, once one accepts that the brain is a physical system. For then, according to the precepts of modern physics, the brain must in principle be treated as a quantum system. The classical concepts are known to he grossly inadequate at the fundamental level, and this fundamental inadequacy of the classical concepts is not confined to the molecular level: it certainly extends to large (e.g., brain-sized) systems. Moreover, quantum theory cannot be coherently understood without dealing in some detail with the problem of the relationship between thoughtlike things and brainlike things: some sort of nontrivial considerations involving our thoughts seems essential to a coherent understanding of quantum theory.

In this respect quantum theory is wholly unlike classical physics, in which a human consciousness is necessarily idealized as a non- participatory observer - - as an entity that can know aspects of the brain without influencing it in any way. This restriction arises because classical physics is dynamically complete in itself: it has no capacity to accommodate any efficacious entities not already completely fixed and specified within its own structure. In quantum theory the situation is more subtle because our perceptions of physical systems are described in a classical language that is unable to express, even in a gross or approximate way, the structural complexity of physical systems, as they are represented within the theory: there is a fundamental structural mismatch between the quantum mechanical description of a physical system and our description of our perceptions of that system. The existence of this structural mismatch is a basic feature of quantum theory, and it opens up the interesting possibility of representing the mind/brain, within contemporary physical theory, as a combination of the thoughtlike and matterlike aspects of a neutral reality.

One could imagine modifying classical mechanics by appending to it the concept of another kind of reality; a reality that would be thoughtlike, in the sense of being an eventlike grasping of functional entities as wholes. In order to preserve the laws of classical mechanics this added reality could have no effect on the evolution of any physical system, and hence would not be (publicly) observable. Because this new kind of reality could have no physical consequences it could confer no evolutionary advantage, and hence would have, within the scientific framework, no reason to exist. This sort of addition to classical mechanics would convert it from a mechanics with a monistic ontology to a mechanics with a dualistic ontology. Yet this profound shift would have no roots at all in the classical mechanics onto which it is grafted: it would be a completely ad hoc move from a monistic mechanics to a dualistic one.

In view of this apparent logical need to move from monistic classical mechanics to a dualistic generalization, in order to accommodate mind, it is a striking fact that physicists have already established that classical mechanics cannot adequately describe the physical and chemical processes that underlie brain action: quantum mechanics is needed, and this newer theory, interpreted realistically, in line with the ideas of Heisenberg, already is dualistic. Moreover, the two aspects of this quantum mechanical reality accord in a perfectly natural way with the matterlike and thoughtlike aspects of the mind/brain. This realistic interpretation of quantum mechanics was introduced by Heisenberg not to accommodate mind, but rather to keep mind out of physics; i.e., to provide a thoroughly objective account of what is happening in nature, outside human beings, without referring to human observers and their thoughts. Yet when this dualistic mechanics is applied to a human brain it can account naturally for the thoughtlike and matterlike aspects of the mind/brain system. The quantum mechanical description of the state of the brain is automatically (see below) an extrinsic-level description, which is the appropriate level for describing brain correlates of thoughts. Moreover, thoughts can be identified with events that constitute efficacious choices. They are integral parts of the quantum mechanical process, rather than appendages introduced ad hoc to accommodate the empirical fact that thoughts exist. These features are discussed in the following sections.

[Sarfatti Note: Very important sentence is "Moreover, thoughts can be identified with events that constitute efficacious choices."]

Press here to continue to Part 2

Stapp and Shimony

Nobel Physicist Brian Josephson on Quantum Physics of Living Matter

Cal Tech Nanobiology

Bill Calvin presents the classical opposition to quantum theories of mind.

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