Mind and Matter: A Physicist’s View

Physicists exploring the structure of the universe have discovered that it is endowed with a deep and remarkable order. The cosmos is both rationally transparent and rationally beautiful. That human beings can understand processes at the macroscopic level of everyday events is scarcely surprising. Evolutionary survival necessity can plausibly be invoked as the selective means that has shaped the development of the hominid brain to facilitate this ability. Yet our scientific powers vastly exceed anything that is made comprehensible in this way. What advantage in the competition for resources is afforded by our ability to make sense of the cloudy and fitful world of subatomic physics, or the vast realms of cosmic curved space–time? Both regimes are remote from direct practical relevance to mundane affairs. Yet we can understand them, despite that understanding calling for the development of counterintuitive modes of thought, quite different from those of everyday. The deep intelligibility of the cosmos is surely a most significant fact. Albert Einstein once said that the only mystery of the universe is that it is comprehensible.

Mathematics 

Equally remarkable is the fact that it is the apparently abstract subject of mathematics that has proved to be the key to unlock the secrets of the cosmos. It is an actual technique in fundamental theoretical physics to seek theories that in their mathematical formulation are expressed in terms of beautiful equations. Mathematical beauty is characterised by qualities such as economy and elegance and a property that the mathematicians call being “deep,” that is, that a seemingly simple definition turns out to lead to extensive and unexpected consequences. The perception of mathematical beauty is, perhaps, not an experience accessible to everyone, but it is something that the mathematicians themselves can recognise and agree about, giving it a persuasivelyintersubjective character. This pursuit of mathematical beauty by the theoretical physicists is no mere aesthetic indulgence, but a heuristic principle of proven value. In just such a way did Albert Einstein discover the equations of general relativity and Paul Dirac the relativistic quantum equation of the electron. These discoveries were then persuasively recognised as offering verisimilitudinous descriptions of nature because of what proved to be their long-term explanatory fruitfulness. For example, the Dirac equation immediately afforded an unanticipated explanation of the known, but not understood, fact that the electron’s magnetic properties were twice as strong as classical physics would have led one to think. Later the same equation led to the wholly unexpected discovery of the existence of antimatter.

Thus, the cosmos has proved not only to be rationally transparent but also rationally beautiful, a fact that gives physicists the reward of experiencing wonder as they pursue the labours of their research. One may summarise this state of affairs by saying that the explorations of fundamental physics have revealed that we live in a universe whose basic patterns of marvellous order make it quite natural to think of it as a world shot through with signs of mind. It is not possible to think seriously about the material universe without taking this mind-suffused character into account. The stuff of the universe is something more subtle and more interesting than a kind of brute inert substance, like the Greek notion of hyle. Its character is quite contrary to the physicalist assumption that reality is essentially mindless. [...]

Dual-aspect monism

[Now,] the insights of science are distinctly discouraging to a dualistic concept of mind and matter as two totally distinct substances. Consideration of the effects of drugs and brain damage on mental functioning certainly encourage taking seriously a close correlation between brain and mind, without necessitating the identification of the two in a crassly reductionist way. Furthermore, as far as science can make out, there seems to be a continuously developing evolutionary history linking the first replicating molecules of 3.5 billion years ago to the human beings of today. On this view, it is natural to see the appearance of thinking entities as the emergence in cosmic history of an astonishing new feature of matter in complex organisation, the evolution into actuality of a potentiality already obscurely present. Taken together, these considerations point the physicist in the direction of seeing humans as psychosomatic unities, beings whose material and mental aspects are both to be taken with equal seriousness, combined in the inseparable and complementary relationship of a unitary person. Neither the extreme of materialism nor the extreme of idealism seems adequate to the complexity of the human being. Instead, some form of dual-aspect monism is surely the point of view to be sought. Of course, this aspiration is easier to state than to achieve. Concerning dual-aspect monism, Thomas Nagel was frank enough to write that the “talk of dual-aspect theory is largely hand waving. It is only to say roughly where the truth might be located, not what it is”. Nevertheless, there are developments taking place in contemporary science that may indicate a promising direction in which to wave. 

Complexity theory 

The principal methodological approach in physical science has been that of reductionism, decomposing a complex system into its simpler component parts. “Divide and rule” has been the motto. The huge success of this technique by no means implies that it is the only story to be told, but simply that it is the easiest story to discover and articulate. However, it is just becoming possible, in quite a small way, to do more than that and to study some moderately complex systems considered in their totalities. Nothing has been investigated so far that is anything like as complex as a single living cell, but even at the modest level attempted, some extremely surprising and significant patterns of behaviour have been manifested which were completely unforeseeable in terms of the properties of constituents. Some of the systems studied have been purely logical and so they were immediately capable of being implemented on a computer. One of these has been a Boolean net of connectivity two, a particular object of study by Kauffman.

Rather than analysing the system in logical terms, it will be simpler to envisage it in terms of an equivalent hardware model. Consider an array of many light bulbs, each of which can be in one of two states, either “on” or “off.” Each bulb is correlated with two other bulbs somewhere else in the array and the system develops in steps. What state a bulb will be in at the next step is determined by the states at the present step of its two correlated bulbs, according to some simple rules (which is where the logical structure comes in). The system is started of in a random pattern of illumination, some bulbs on and some bulbs off, and then left to develop according to these rules. One might have expected that nothing very interesting would happen and the array would just twinkle away haphazardly as long as it was let to do so. This is far from being the case. The system soon settles down to circling through a very limited set of patterns of illumination. If there are 10,000 bulbs in the array there will be about 100 such different patterns. (More generally, in an array of n bulbs it turns out that there will be about n^1/2 such patterns.) Since the number of distinct possible patterns of illumination in the 10,000-bulb array is 2¹⁰⁰⁰⁰, or about 10³⁰⁰⁰, this represents the spontaneous generation of an altogether astonishing degree of orderly behaviour.

Similar powers of self-organisation have also been discovered in physical systems. The second law of thermodynamics states that in isolated systems, entropy (the measure of disorder) increases, leading eventually to the quiescent state of thermal equilibrium. However, dissipative systems, which exchange energy and entropy with their environment, can generate and maintain substantial patterns of internal order by exporting disorder into their surroundings. They exist far from thermal equilibrium. All living beings are dissipative systems. Whenever we breathe out carbon dioxide, we are exporting entropy into our environment.

These spontaneously emergent self-organising properties of complex systems are very striking. However, at present, complexity theory is at the stage of natural history rather than mature science. It explores the behaviour of many particular systems, and repeatedly discovers astonishing degrees of self-organisation, but it has not yet attained an over-arching theory explaining in general terms what is going on. It is impossible not to believe that there is such a deep theory awaiting discovery, and one may well anticipate its being brought to light in the course of the twenty-first century. Even now, it is possible to identify two general characteristics the theory may be expected to have. One, obviously enough, is that it will be holistic, dealing with systems in their totalities and not simply decomposing them into constituent bits and pieces. The second is that it will have, as one of its central concepts, what one might call “information,” the specification of dynamical patterns of behaviour. Much work remains to be done in refining and defining this concept, but it seems clear that as holistic physics develops, information will take its place alongside energy as a basic category of science. The old physics of constituent interactions, which of course still remains an essential component of what is going on, was concerned with the exchange of energy between the parts that made up the whole. The new holistic physics will be concerned with using information to characterise the overall pattern of total energy flow. 

[...]

At present, one must admit that these ideas are just the toys of thought, but they seem useful toys with which to play. The dualities of parts/wholes and energy/information bear some faint but suggestive analogy to the much more profound dualities of matter/mind and brain/thought. Of course vast extrapolation would be needed to carry one from the sort of complex systems studied today to anything approaching an account of human nature. In particular, an immense extension and generalisation of the concept of information would be needed to transform the comparative banality of considering patterns of energy flow into anything remotely resembling the character of human thought. Nevertheless, enough has been discussed to show that it is entirely possible to take with appropriate seriousness all that physics can tell us about the nature of matter, without feeling that we have to deny the complementary reality of our experience of mind.