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|This was the last of my father's major lectures, and he delivered versions of it throughout the 1980s.|
LIFE AND MIND IN THE UNIVERSE
By George Wald
By George Wald
I have come to the end of my scientific life facing two great problems. Both are rooted in science; and I approach them as only a scientist would. Yet both I believe to be in essence unassimilable as science. That is scarcely to be wondered at, since one involves cosmology, the other consciousness.
I will begin with the cosmology.
I. A Universe That Breeds Life
There is good reason to believe that we are in a universe permeated with life, in which life arises, given enough time, wherever the conditions exist that make it possible. How many such places are there? Arthur Eddington, the great British physicist, gave us a formula: one hundred billion stars make a galaxy, and one hundred billion galaxies make a universe. The lowest estimate I have ever seen of the fraction of them that might possess a planet that could support life is one percent. That means one billion such places in our home galaxy, the Milky Way; and with about one billion such galaxies within reach of our telescopes, the already observed universe should contain at least one billion billion -- 1018 -- places that can support life
So we can take this to be a universe that breeds life; and yet, were any one of a considerable number of physical properties of our universe other than it is -- some of those properties basic, others seeming trivial, almost accidental -- that life, that now appears to be so prevalent, would become impossible, here or anywhere.
I can only sample that story here and, to give this account a little structure, I shall climb the scale of states of organization of matter, from small to great.
But first, a preliminary question: How is it that we have a universe of matter at all?
Our universe is made of four kinds of so-called elementary particles: neutrons, protons, electrons, and photons, which are particles of radiation. (I disregard neutrinos, since they do not interact with other matter; also the host of other particles that appear transiently in the course of high‑energy nuclear interactions.) The only important qualification one need make to such a simple statement is that the first three particles exist also as antiparticles, the particles constituting matter, the anti-particles anti-matter. When matter comes into contact with anti-matter they mutually annihilate each other, and their masses are instantly turned into radiation according to Einstein’s famous equation, E = mc2, in which E is the energy of the radiation, m is the annihilated mass, and c is the speed of light.
The positive and negative electric charges that divide particles from anti-particles are perfectly symmetrical. So the most reasonable expectation is that exactly equal numbers of both particles and anti-particles entered the Big Bang, the cosmic explosion in which our universe is thought to have begun. In that case, however, in the enormous compression of material at the Big Bang, there must have occurred a tremendous storm of mutual annihilation, ending with the conversion of all the particles and anti-particles into radiation. We should have come out of the Big Bang with a universe containing only radiation.
Fortunately for us, it seems that a tiny mistake was made. In 1965, Arno Penzias and Robert Wilson at the Bell Telephone Laboratories in New Jersey discovered a new microwave radiation that fills the universe, coming equally from all directions, wherever one may be. It is by far the dominant radiation in the universe; billions of years of starlight have added to it only negligibly. It is commonly agreed that this is the residue remaining from that gigantic firestorm of mutual annihilation in the Big Bang.
It turns out that there are about one billion photons of that radiation for every proton in the universe. Hence it is thought that what went into the Big Bang were not exactly equal numbers of particles and anti-particles, but that for every billion anti-particles there were one billion and one particles, so that when all the mutual annihilation had happened, there remained over that one particle per billion, and that now contitutes all the matter in the universe -- all the galaxies, the stars and planets, and of course all life.
I should like now to raise two problems to do with protons and electrons, one involving their masses, the other their electric charge.
Every atom has a nucleus composed of protons and neutrons, except the smallest one, hydrogen, which has only one proton as its nucleus. Electrons orbit these nuclei at distances relatively greater than separate our sun from its planets. Both protons and neutrons have masses almost two thousand times the mass of an electron -- 1840 times when I last looked -- so virtually the whole mass of an atom is in its nucleus. Hence the atom is hardly disturbed at all by the motions of its electrons, and an atom can hold its position in a molecule, and molecules their positions in larger structures. Only that circumstance permits molecules to hold their shapes, and solids to exist.
If on the contrary the protons and neutrons were closer in mass to the electrons, whether light or heavy, then the motions of the electrons would be reflected in reciprocal motions by the others. All structures composed of such atoms would be fluid; in such a universe nothing would stay put. There could not be the fitting together of molecular shapes that permits not only crystals to form, but living organisms.
And now, electric charge: How does it come about that elementary particles so altogether different otherwise as the proton and electron possess the same numerical charge? How is it that the proton is exactly as plus-charged as the electron is minus-charged?
It may help to accept this as a legitimate scientific question to know that in 1959 two of our most distinguished astrophysicists, Lyttleton and Bondi, proposed that in fact the proton and electron differ in charge by the almost infinitesimal amount, 2 x 10 -18e -- two billion billionths e, in which e is the already tiny charge on either the proton or electron. The reason they made that proposal is that, given that nearly infinitesimal difference in charge, all the matter in the universe would be charged, and in the same sense, plus or minus. Since like charges repel one another, all the matter in the universe would repel all the other matter, and so the universe would expand, just as it is believed to do. The trouble with that idea is that yes, the universe would expand, but -- short of extraordinary special dispensations - it would not do anything else. Even so small a difference in electric charge would be enough to overwhelm the forces of gravitation that bring matter together; and so we should have no planets, no stars, no galaxies -- and, worst of all, no physicists.
No need to worry, however. Shortly after Lyttleton and Bondi’s proposal, John King and his group at the Massachusetts Institute of Technology began to test experimentally whether the proton and electron differ in charge, and found that the charges appear to be wholly identical. That is an extraordinary fact, and not made easier to understand by the present belief that, though the electron is a single, apparently indivisible particle, the proton is made up of three quarks, to of them with charges of +2/3 e, and one with a charge of -1/3 e.
To summarize, if the proton and neutron did not have enormously greater mass than the electron, all matter would be fluid; and if the proton and electron did not possess exactly the same electric charge, no matter would aggregate. These are primary conditions for the existence of life in the universe.
Now, to leave the elementary particles and go on to atoms, to elements. Of the 92 natural elements, ninety-nine percent of the living matter we know is composed of just four: hydrogen (H), oxygen (O), nitrogen (N), and carbon (C). That is bound to be true wherever life exists in the universe, for only those four elements possess the unique properties upon which life depends.
Their unique position in chemistry can be stated in a sentence: They -- in the order given -- are the lightest elements that achieve stable electronic configurations (i.e., those mimicking the inert gases) by gaining respectively one, two, three, and four electrons. Gaining electrons, in the sense of sharing them with other atoms, is the mechanism of forming chemical bonds, hence molecules. The lightest elements make not only the tightest bonds, hence the most stable molecules, but introduce a unique property crucial for life: of all the natural elements, only oxygen, nitrogen and carbon regularly form double and triple bonds with one another, so saturating all their tendencies to combine further.
Now, professors sometimes tell their students foolish things, which the students carefully learn and reproduce on exams and eventually teach the next generation. When chemistry professors teach the periodic system of elements, one has those horizontal periods of the elements and the professors say, “If you go down vertically, the elements repeat their same properties.” That is utter nonsense, as any kid with a chemistry set would know. For under oxygen comes sulfur. Try breathing sulfur somethime. Under nitrogen comes phosphorus. There is not any phosphorus in that kid’s chemistry set. It is too dangerous; it bursts into flame spontaneously on exposure to air. And under carbon comes silicon.
If that chemistry professor were talking sense, there are two molecules that should have very similar properties: carbon dioxide (CO2) and silicon dioxide (SiO2). Well, in carbon dioxide the central carbon is tied to both of the oxygen atoms by double bonds O=C=O. Those double bonds completely saturate the combining tendencies of all three atoms, hence CO2 is a happy, independent molecule. It goes off in the air as a gas, and dissolves in all the waters of the Earth, and those are the places from which living organisms extract their carbon.
But silicon cannot form a double bond, hence in silicon dioxide the central silicon is tied to the two oxygens only by single bonds, leaving four half‑formed bonds -- four unpaired electrons -- two on the silicon and one on each oxygen, ready to pair with any other available lone electrons. But where can one find them? Obviously on neighboring silicone dioxide molecules, so each molecule binds to the next, and that to the next, and on and on until you end up with a rock -- for example quartz, which is just silicone dioxide molecules bound to one another to form a great super-molecule. The reason quartz is so hard is that to break it one must break numerous chemical bonds. And that is why, though silicon is 135 times as plentiful as carbon in the Earth’s surface, it makes rocks, and to make living organisms one must turn to carbon. I could make a parallel argument for oxygen and nitrogen.
These four elements, Hydrogen, carbon, oxygen and nitrogen, also provide an example of the astonishing togetherness of our universe. They make up the “organic” molecules that constitute living organisms on a planet, and the nuclei of these same elements interact to generate the light of its star. Then the organisms on the planet come to depend wholly on that starlight, as they must if life is to persist. So it is that all life on the Earth runs on sunlight. I do not need spiritual enlightenment to know that I am one with the universe -- that is just good physics.
Now let’s go up a step, to molecules. By far the most important molecule for living organisms is water. I think we can feel sure that if there is no liquid water, there is no life, anywhere in the universe. Water also happens to be the strangest molecule in all chemistry; and its strangest property is that ice floats. If ice did not float, I doubt that life would exist in the universe.
Virtually everything contracts on cooling. That is how we make thermometers: a bit of red-dyed alcohol, mercury if you can afford it, put in a capillary tube contracts on cooling, and you read the temperature. Everything does this. So does water, down to four degrees centigrade. But between four and zero degrees centigrade, where it freezes, it expands, so rapidly that the ice that forms is less dense than liquid water. The complete hydrogen bonding among the water molecules in ice holds them more widely spaced than in liquid water, so ice floats.
Nothing else does that. But what if water behaved like virtually everything else, and continued to contract on cooling? Then the increasingly dense water would constantly be sinking to the bottom, and freezing would begin at the bottom, , not as now at the top, and would end by freezing the water solidly. A really large mass of ice takes forever to melt, even at higher temperatures.
In my region of the United States, New England, the fishermen wait all winter for the ponds to freeze over. That is the best time to go fishing. They take their fishing equipment in one hand, a bottle of whiskey in the other, and cut themselves a round hole in the ice. Up to that point the fish were getting along fine. These creatures live through the winter with no trouble, and as soon as the warm weather comes, that skin of ice on the surface melts and with that everything is free again. If ice did not float, it is hard to see how any life could survive a cold spell. On any planet in the universe, if a freeze occured even once in many millions of years, that would probably be enough to block the rise of life, and to kill any life that had arisen.
And now another step up, to stars. The first generation of stars began as hydrogen, and lived by fusing it to helium. A hydrogen atom is composed of a proton as nucleus and one electron moving about it; but at temperatures of about five million degrees they are driven apart, and one is dealing with naked protons, hydrogen nuclei. Now four such protons, each of mass 1, begin to fuse to a helium nucleus of about mass 4, but in this process a very small amount of mass is lost -- four protons have a slightly larger mass than a helium nucleus -- and this tiny loss of mass is converted into radiation according to Einstein’s equation, E=mc2. Even so small a loss of mass yields a huge amount of radiation, and that flood of radiation pours out in the interior of what had been a collapsing mass of gas and stops its further collapse, stabilizing it, and is also the source of starlight.
Eventually, though, this process runs every star short of hydrogen. With that, it generates less energy and so begins to collapse again, and as it collapses it heats up some more. When the temperature in its deep interior reaches about one hundred million degrees, the helium nuclei begin to fuse. Two helium nuclei, each of mass 4, fuse to make beryllium, of mass 8, a nucleus so unstable as to disintegrate within 10-16 second (ten million billionths of a second).Yet in these enormous masses of material and at such high temperatures there are always a few beryllium nuclei, and here and there one of them adds another helium: 8 and 4 make 12, the mass of carbon. That is how carbon comes into the universe. Then a carbon nucleus can add another helium: 12 plus 4 make 16, the mass of oxygen, and that is how oxygen enters the universe. Also carbon, even at somewhat lower temperatures, can add hydrogens, and carbon-12 plus two hydrogens make 14, the mass of nitrogen. That is how nitrogen enters the universe.
These new processes, together with its heating by collapse, have by now puffed up our star to enormous size. It has become a Red Giant, a dying star. In its dying, it has made the elements of which life is composed. It is a moving realization that stars must die before organisms can live.
These Red Giants are in a delicate condition, and by distillation and in such stellar catastrophes as flares, novas, and supernovas they spew their substance out to become part of the great masses of gases and dust that fill all interstellar space. Over eons of time, great masses of those gases and dust are drawn together by their mutual gravitation to form new generations of stars. But such latecomers, unlike the first generation of stars made wholly of hydrogen and helium, contain also carbon, nitrogen, and oxygen. And we know that our Sun is such a later-generation star because we are here, because the Earth is one of those planets in the universe that supports life.
Finally, we have a cosmic principle: To have such a universe as this requires an extraordinary balance between two great cosmic forces: that of dispersion (expansion), powered by the Big Bang, and that of aggregation, powered by gravitation. If the forces of expansion were dominant, that would yield an isotropically dispersed universe lacking local clusters, galaxies or planetary systems; all the matter would be flying apart, and there would be no large solid bodies, hence no place for life. If, on the contrary, gravitation were dominant, the initial expansion produced by the Big Bang would have slowed up and come to an end, followed by a universal collapse, perhaps in preparation for the next Big Bang. There would be no time for life to arise, or it would be quickly destroyed.
We live in a universe in which it has just lately been realized that those two forces are in exact balance, so that the universe as a whole is expanding wherever one looks, everything very distant is going away from us, but locally there are so-called local groups and clusters, where whole clusters of galaxies are held together by gravitation. Our own relatively small cluster contains, in addition to the Milky Way, the Andromeda galaxy (M31). It is very much like our galaxy, but a little smaller, and there is also a still smaller galaxy, all part of our local group. Most of you have probably heard that we measure the expansion of the universe by the so-called red shift. The further one looks out into space, the redder the light is, compared to the same sources on earth. That is interpeted as an expression of the Doppler Effect, and taken to mean that the more distant an astronomical body, the faster it is receding from us. But the first such color shift ever to be discovered, by the astronomer Slipher back in 1912, was not a red shift by a blue shift. He was looking at our sister galaxy, Andromeda, and observed a blue shift because, far from receding, the Andromeda galaxy is coming toward us at about 125 miles per second. It is just this exact balance between the steady expansion of the universe as a whole and its stability locally that affords both enormous reaches of time and countless sites for the development of life.
I have here only sampled briefly an argument that extends much further. The nub of that argument is that our universe possesses a remarkably detailed constellation of properties, and as it happens, it is just that constellation that breeds life. It takes no great intelligence or imagination to conceive of other universes, indeed any number of them, each of which might be perfectly good, stable universes, but lifeless.
How did it happen that, with what seem to be so many other options, our universe came out just as it did? From our own self‑centered point of view, that is the best way to make a universe: But what I want to know is, how did the universe find that out?
It may be objected that the question would not arise if we were not here to ask it. Yet here we are, and strangely insistent on asking that kind of question. Perhaps that indeed is the answer: That this is a life‑breeding universe precisely in order eventually to bring forth creatures that ask and attempt to answer such questions, so that through them the universe can come not only to be, but to be known; indeed can come to know itself. That leads me to my other great problem, that of consciousness.
The problem of consciousness was hardly avoidable for someone like me, who has spent most of his scientific life working on mechanisms of vision. That is by now a very active field, with thousands of workers. We have learned a lot, and expect to learn much more; yet none of it touches or even points however tentatively in the direction of telling us what it means to see.
I learned my business on the eyes of frogs. The retina of a frog is very much like a human retina. Both contain two kinds of light receptors, rods for vision in dim light and cones for bright light; the visual pigments are closely similar in chemistry and behavior; both have the same three fundamental nerve layers, and the nervous connections to the brain are much alike. But I know that I see. Does a frog see? It reacts to light -- so does a photocell‑activated garage door. But does it know it is responding, is it aware of visual images?
There is nothing whatever that I can do as a scientist to answer that question. That is the problem of consciousness: it is altogether impervious to scientific approach. As I worked on visual systems -- it would have been the same for any other sensory mode, let alone more subtle or complex manifestations of mental activity -- this realization lay always in the background. Now for me it is in the foreground. I think that it involves a permanent condition: that it never will become possible to identify physically the presence or absence of consciousness, much less its content.
I of course have some preconceptions, but the only unequivocally sure thing is what goes on in my own consciousness. Everything else that I think I know involves some degree of inference. I have all kinds of evidence that other persons are conscious. It helps that they tell me so, and display other evidences of consciousness in speech and writing, art and technology. I believe that other mammals are conscious; and birds -- that business of singing at dawn and sunset makes me think that they are essentially poetic creatures. But when I get to frogs I worry, and fishes even more so. Those animals at least respond reasonably to light and some visual images. But I have worked also on the numerous and anatomically magnificent eyes of scallops, without finding any indication that these animals see, beyond reacting to a passing shadow. The last animals whose vision I worked on with my own hands were worms with great big bulging eyes, with everything you could ask for in an eye. The eyes yielded fine electrical responses to light, but I never could get the worms themselves to give any indication whatever that they responded to light. Maybe they didn’t like being with me.
Any assumption regarding the presence or absence of awareness in any nonhuman animal remains just that: an unsupported assumption. Matters are no different with inorganic devices. Does the photoelectrically activated garage door resent having to open when a car’s headlights shine on it? I think not. Does a computer that has just beaten a human opponent at chess feel elated? I believe not. But there is nothing I can do to shore up those assumptions either.
Consciousness is not part of that universe of space and time, of observable and measurable quantities, that is amenable to scientific investigation. For a scientist, it would be a relief to dismiss it as unreal or irrelevant. I have heard distinguished scientists do both. In a discussion with the physicist P. W. Bridgman some years ago, he spoke of consciousness as “just a way of talking.” His thesis was that only terms that can be defined operationally have meaning; and there are no operations that define consciousness. In the same discussion, the psychologist B. F. Skinner dismissed consciousness as irrelevant to science, since confined to a private world, not accessible to others.
Unfortunately for such attitudes, consciousness is not just an epiphenomenon, a strange concomitant of our neural activity that we project onto physical reality. On the contrary, all that we know, including all our science, is in our consciousness. It is part, not of the superstructure, but of the foundations. No consciousness, no science. Perhaps, indeed, no consciousness, no reality -- of which more later.
Though consciousness is the essential condition for all science, science cannot deal with it. That is not because it is an unassimilable element within science, but just the opposite: science is a highly digestible element within consciousness, which includes science as a limited territory within the much wider reality of whose existence we are conscious. Consciousness itself lies outside the parameters of space and time that would make it accessible to science, and that realization carries an enormous consequence: consciousness cannot be located. But more: it has no location.
Some years ago I talked about this with Wilder Penfield, the great Canadian neurosurgeon. In the course of his therapeutic activities he had unprecedented opportunities to explore the exposed brains of conscious patients, and hoped in this way to discover the seat of human consciousness. I asked him, “Why do you think consciousness is in the brain? Maybe it’s all over the body.”
He chuckled, and said, “Well, I’ll keep on trying.”
About two years later, I met him again and he said to me, “I’ll tell you one thing: it’s not in the cerebral cortex!”
Shortly afterward came the exciting announcement that the so‑called reticular formation in the brain stem of mammals contains an arousal center, a center that seems to wake creatures up and produce awareness. The problem with all such observations is that one cannot know whether one is dealing with a source or with part of the machinery of reception and transmission. It is as though, finding that the removal of a transistor from a television set stopped the transmission, one concluded it to be the source of the program.
How could one possibly locate a phenomenon that one has no means of identifying -- neither its presence nor absence -- nor any known parameters of space, time, energy exchange, by which to characterize merely its occurrence, let alone its content? The very idea of a location of consciousness is absurd. Just as with Heisenberg’s uncertainty principle, we have more to deal with here than technical inadequacy, with a perhaps temporary lack of means of observation and measurement. What we confront is an intrinsic condition of reality. It is not only that we are unable to locate consciousness: it has no location.
Consider pain, the most primitive of sensory responses, and most closely connected with survival. I have had to kill many animals in the course of my work, and have tried always to inflict a minimum of pain. But do other animals than man feel pain? Many physiologists assert that only warm‑blooded animals feel pain, and some of their publications have stated this as an official view. The National Eye Institute announced only in 1979 a first break with this position, asking workers with cold‑blooded animals to try to avoid giving them “unnecessary pain.” When I lop off the head of a frog, I assume that the headless body is beyond pain; but is the head? So I hastily destroy the brain, and hope that ends the problem. Yet I have heard Wilder Penfield say that once a human brain has been exposed, one could operate on it with a spoon without causing an unanesthetized patient any great discomfort. And what of a worm, any small piece of which writhes on being pinched?
Recently there has been a controversy in the American press involving some physicians having asserted that a human fetus feels pain in an abortion. The very idea should raise deep concern about the very widespread Arnerican practice of circumcising male newborns, performed routinely without anesthesia, the physicians having assured the rnothers that the nervous systems of their infants have not yet developed sufficiently for them to feel pain. All such assertions are equally groundless. Even as regards so primitive a concept as pain, we are altogether baffled in trying to substantiate its occurrence or absence.
I used to show students a film made by the French zoologist Faure‑Fremiet on the feeding behavior of protozoa. Many of our sturdiest concepts of the apparatus required for animal behavior are mocked by these animalcules, particularly by the ciliates; for in one cell they do everything: move about, react to stimuli, feed, digest, excrete, on occasion copulate and reproduce. In this film one saw them encountering problems and solving them, much as would a mammal. I remember best a carnivorous protozoon tackling a microscopic bit of muscle. It took hold of the end of a fibril, and backed off at an angle, as though to tear it loose. When the fibril would not give, the protozoon came in again, then backed away at a new angle, worrying the fibril loose, much as a dog might have done, worrying loose a chunk of meat. It was hard, watching that single cell at work, not to anthropomorphize. Did it know what it was doing?
But then, ciliate protozoa are the most complex cells we know. How about a cell highly specialized to perform a single function in a higher organism, a nerve cell for example, that can only transmit an impulse? Once, years ago, I was visiting the invertebrate physiologist, Ladd Prosser, at the University of Illinois in Urbana. He took me into his laboratory, where he was recording the electrical responses from a single nerve cell in the ventral nerve cord (which takes the place of our spinal cord) of a cockroach. It was set up to display the electrical potentials on an oscilloscope screen, and simultaneously to let them sound through a loudspeaker. I was hearing a slow, rhythmic reverberation, coming to a peak, then falling off to silence, then starting again, each cycle a few seconds, like a breathing rhythm. Prosser remarked, “That kind of response is typical of a dying nerve cell.”
“My God!” I said, “It’s groaning! You’ve given it a voice, and it’s groaning!”
Was that nerve cell expressing a conscious distress? Is something like that the source of a person’s groaning? There is no way whatever of knowing.
So that is the problem of mind -- consciousness -- a vast, unchartable domain that includes all science, yet that science cannot deal with, has no way of approaching; not even to identify its presence or absence; that offers nothing to measure, and nothing to locate, since it has no location.
III. Mind and Matter
A few years ago it occurred to me -- albeit with some shock to my scientific sensibilities -- that my two problems, that of a life‑breeding universe, and that of consciousness that can neither be identified nor located, might be brought together. That would be with the thought that mind, rather than being a late development in the evolution of organisms, had existed always: that this is a life‑breeding universe because the constant presence of mind made it so.
I have been in experimental science long enough to know that when you have done an experiment that comes out surprisingly well, the thing to do is enjoy it, because the next time you try it, it may not work. So when this idea struck me, I was elated, I enjoyed it immensely. But I was also embarrassed, because this idea violated all my scientific feelings. It took only a few weeks, however, for me to realize that I was in excellent company. That kind of thought is not only deeply embedded in millenia‑old Eastern philosophies; it is stated explicitly or strongly implied in the writings of a number of great and quite recent physicists.
Perhaps it was in part because I am a biologist that the idea at first seemed so strange to me. Biologists tend to be embarrassed by consciousness. As it is an attribute of some living organisms, they feel that they should know about it, and should indeed be in position to straighten out physicists about it, whereas exactly the opposite is true. Physicists live with the problem of consciousness day in and day out. Early in this century it became evident to all physicists that the observer is an intrinsic component of every physical observation. Physical reality is what physicists recognize to be real. One cannot separate the recognition of existence from existence. As Erwin Schrödinger put it: “The world is a construct of our sensations, perceptions, memories. It is convenient to regard it as existing objectively on its own. But it certainly does not become manifest by its mere existence.”
Let me give a simple example of the intervention of mind in physical observation: Most readers are probably aware that radiation -- light, indeed all elementary particles -- exhibits simultaneously the properties of waves and of particles, though those properties are altogether different -- indeed, mutually exclusive. This is the prime example of a widespread class of relationships that Neils Bohr brought together in his principle of complementarity, which notes that numbers of phenomena, in and out of physics, exhibit such mutually exclusive sets of properties; one just has to live with them.
Enter consciousness: the physicist, setting up an experiment on radiation, decides beforehand which of those sets of properties he will encounter. If he does a wave experiment, he gets a wave answer; from a particle experiment he gets a particle answer. To this degree, all physical observation is subjective.
It is primarily physicists who in recent times have expressed most clearly and forthrightly this pervasive relationship between mind and matter, and indeed at times the primacy of mind. Arthur Eddington in 1928 wrote, “the stuff of the world is mind‑stuff ... The mind‑stuff is not spread in space and time.... Recognizing that the physical world is entirely abstract and without ‘actuality’ apart from its linkage to consciousness, we restore consciousness to the fundamental position . . .”
Von Weizsacker in 1971 states as “a new and, I feel, intelligible interpretation of quantum theory” what he calls his “Identity Hypothesis: Consciousness and matter are different aspects of the same reality.”
I like most of all Wolfgang Pauli’s formulation, from 1952: “To us . . . the only acceptable point of view appears to be the one that recognizes both sides of reality -- the quantitative and the qualitative, the physical and the psychical -- as compatible with each other, and can embrace them simultaneously . . . It would be most satisfactory of all if physis and psyche (i.e., matter and mind) could be seen as complementary aspects of the same reality.”
What this kind of thought means essentially is that one has no more basis for considering the existence of matter without its complementary aspect of mind, than for asking that elementary particles not also be waves.
As for this seeming a strange viewpoint for a scientist -- at least until one gets used to it -- as in so many other instances, what is wanted is not so much an acceptable concept as an acceptable rhetoric. If I say, with Eddington, “the stuff of the world is mind‑stuff,” that has a metaphysical ring. But if I say that ultimate reality is expressed in the solutions of the equations of quantum mechanics, quantum electrodynamics, and quantum field theory -- that sounds like good, modern physics. Yet what are those equations, indeed what is mathematics, but mind‑stuff? -- virtually the ultimate in mind‑stuff and for that reason deeply mysterious.
IV. The Evolution of Consciousness
I think that we now possess, at least in outline, all that is needed to shape a credible view of the plan of this universe, and of the place in it of life and mind.
That view begins with a sense of the deep interpenetration of the coneepts, to be, and to be known -- existence, and its recognition.
Some years ago I began to entertain the thought that a universe that to be needs to be known, to that end has taken on a design that breeds and fosters life; so that life might eventually, here and there, evolve scientists who could cast back upon the history that produced them, and could begin to understand it. That, through their knowing, the universe could achieve increasingly the reality of becoming known, of coming to know itself. Let me talk a little frank nonsense about this, make of it what you will: It would be a poor thing to be an atom in a universe without physicists. And physicists are made of atoms. A physicist is the atom’s way of knowing about atoms.
Recently, to my surprise and that of some of the physicists most involved, this kind of thinking has been given the rather pretentious name, “the anthropic principle.” It states essentially what I have just said: that the universe possesses the properties it does in order eventually to produce physicists. Apart from meanderings in this direction, it emerged explicitly in a short paper by Dicke at Princeton, pointing out, for example, that the Hubble age of the universe is not wholly arbitrary, since about that much time was needed for physicists to appear. I used to hear this idea expressed in the form of a joke: “Why is the world five -- or ten or twenty -- billion years old?” And the answer: “Because it took that long to find that out.”
Of course, implicit in such talk is the recognition that a universe in which mind can eventually achieve such overt expression as in science, art and technology must be at its core, from its inception, in some sense a knowing universe; that it must in some sense possess mind as its pervasive and enduring attribute. What we recognize as the material universe, the universe of space and time and elementary particles and energies, is then an avatar, the materialization of primal mind. In that sense there is no waiting for consciousness to arise. It is there always. What we wait for in the evolution of life is only the culminating event, the emergence of creatures that in their self‑awareness can articulate consciousness, can give it a voice and, being also social creatures, can embody it in culture: in technology, art and science.
All of this, however, provocative as it is, does not yet express what I think is the crux of the matter: A universe that through breeding life evolves eventually science‑, art‑, and technology‑making creatures, presumably in many places, enters thereby a new phase in its evolution, that now includes means for the independent evolution of consciousness. For such creatures found societies and establish cultures. They invent languages, writing, institutions for accumulating, storing and propagating information, speculation and belief.
Those creatures were evolved anatomically and physiologically through natural selection, a process that involves three components: a ceaseless outpouring of inherited variations, both advantageous and disadvantageous; a mechanism of inheritance; and a competition for survival, in the course of which those organisms and properties that function better are retained, and those that function less well are discarded.
Cultures -- on our planet, human cultures -- exhibit all these elements. They too display endless variations, both advantageous and disadvantageous to survival; mechanisms of cultural inheritance, mainly if not entirely Lamarckian (nongenic), since they involve almost entirely acquired (i.e., learned) characters; and continuous competition, an unceasing interplay of absorption and rejection, domination and subjection.
So is launched an independent evolution of consciousness, superimposed upon and parallel with the continuing evolution of anatomy and physiology. It takes its place as an intrinsic development in cosmic evolution. That universe in which, from its inception, matter and mind have been the complementary aspects of reality, now comes to develop, and regularly, in many places, complementary systems of evolution by natural selection, physical and mental.
I think that is the substantive outcome of our argument. It accords to humankind and its like elsewhere in the universe a great place in cosmic evolution. It gives our species here a transcendent worth and dignity, among the many kinds of creatures that inhabit our planet. It tells us our place in the universe: it is to know and create, and to try to understand, as we alone can do under our sun.