|
*
This chapter is rather tough going. Should the stranger to modern physics be baffled by some passages, I hope he will at least gain a general impression of that weird
Wonderland.
Part 1
IF THE facts reported in the previous section arouse incredulity and a certain intellectual revulsion it is because they seem to contradict what most people believe to be the immutable laws of physics. The main comfort comes from modern physics itself. This is not a paradox, but a consequence of the profound transformation of the physicist's world view, which began in the late nineteenth century and shattered his fundamental concepts of the nature of reality, the meaning of natural law, and the validity of our ideas about space, time, matter and causality. Einstein's writing a preface to Upton Sinclair's
Mental Radio was a symbolic act; and it is not by chance that so many leading physicists appear among the Presidents and Council members of the Society for Psychical Research. For the deeper the physicist intruded into the realms of the sub-atomic and super-galactic dimensions, the more intensely he was made aware of their paradoxical and commonsense-defying structure, and the more open-minded he became towards the possibility of the seemingly impossible. His own world, based on relativity and quantum theory, is in fact a world of impossibles. Its strange and tantalising flavour is reflected in a remark by J. R. Oppenheimer, Chairman of the Los Alamos
project:
If we ask ... whether the position of the electron remains the same, we must say "No"; if we ask whether the electron's position changes with time, we must say "No"; if we ask whether the electron is at rest, we must say "No", if we ask whether it is in motion, we must say
"No"(1).
In a similar way Werner Heisenberg, one of the giants of quantum physics, emphasises in his autobiography again and again that "atoms are not
things. The electrons which form an atom's shells are no longer things in the sense of classical physics, things which could be unambiguously described by concepts like location, velocity, energy, size. When we get down to the atomic level, the objective world in space and time no longer exists, and the mathematical symbols of theoretical physics refer merely to possibilities, not to
facts"(2).
Heisenberg will probably go down in history as the man who put an end to causal determinism in physics-and thereby in philosophy - with his celebrated Principle of Indeterminacy (alternatively referred to as the Principle of Uncertainty) for which he got the Nobel Prize in 1931*. The best one can do to convey its meaning to the general reader is by a coarse analogy. A certain static quality of much Renaissance painting is due to the fact that the human figures and their distant background are both in sharp focus - which is optically impossible: when we focus on a close object the background gets blurred, and vice versa. Heisenberg's principle means that in studying the elementary constituents of matter the physicist finds himself in a similar predicament (though of course for different reasons). In classical physics a particle must at any time have a definable location and velocity; on the sub-atomic level, however, the situation turns out to be radically different. The more accurately the physicist is able to determine the location of an electron, for instance, the more uncertain its velocity becomes; and vice versa, if he knows its velocity, the location of the electron becomes a blur. This inherent indeterminacy of sub-atomic events is due to the ambiguous and elusive nature of these smallest particles of matter, which in fact are not particles or "things" at all. They are Janus-faced entities which behave under certain circumstances like hard little pellets, under different circumstances, however, like waves or vibrations propagated in a medium devoid of any physical attributes. As Sir William Bragg put it, they seem to be waves on Mondays, Wednesdays and Fridays, and particles on Tuesdays, Thursdays and
Saturdays.
* The reader may find the frequent mention of Nobel awards tiresome. It is intended as a reassurance that some of the strange theories in contemporary physics and psychology discussed in this section were propounded not by cranks but by scientists eminent in their fields.
At the beginning of this century Lord Rutherford and the great Danish physicist Niels Bohr designed a beguilingly simple model of the atom as a miniature solar system, in which negatively charged electrons circle like planets round a positively charged nucleus. But the model ran into one paradox after another: the electrons behaved quite unlike planets: they kept jumping from one orbit into a different orbit without passing through intervening space - as if the earth were suddenly transferred into the orbit of Mars without having to travel. The orbits themselves were not linear trajectories but wide, blurred tracks, and it was meaningless to ask for instance at what point of its orbit the electron of the hydrogen atom was at any given moment of time; it was equally everywhere. As Bertrand Russell wrote in
1927:
For ought we know an atom may consist entirely of the radiations which come out of it. It is useless to argue that radiations cannot come out of nothing ... The idea that there is a hard little lump there, which
is the electron or proton, is an illegitimate intrusion of commonsense notions derived from touch ... Matter is a convenient formula for describing what happens where it
isn't(3).
But worse was to come ... The beautifully simple Rutherford-Bohr model had to be abandoned in favour of a mathematical theory which got rid of the worst paradoxes - but at the price of renouncing any claim of intelligibility or representability in terms of three-dimensional space, time, matter or causation. "The very attempt", Heisenberg wrote, "to conjure up a picture [of elementary particles] and think of them in visual terms is wholly to misinterpret them"(4). Modern physics seems to obey the Second Commandment: "Thou shalt not make unto thee any graven image" - either of gods or of protons.
In his The Nature of the Physical World (1928) Sir Arthur Eddington introduced his famous "parable of the two writing desks". One is the antique piece of furniture on which his elbows solidly rest while writing; the other is the desk as the
physicist conceives it, consisting almost entirely of empty space, sheer nothingness, sprinkled with unimaginably tiny specks, the electrons whirling round their nuclei, but separated from them by distances a hundred thousand times their own size. And in between - nothing: apart from those few forlorn specks, the interior of the atom is empty. Eddington concluded:
In the world of physics we watch a shadowgraph performance of familiar life. The shadow of my elbow rests on the shadow-table as the shadow-ink flows over the shadow-paper ... The frank realisation that physical science is concerned with a world of shadows is one of the most significant of recent
advances(5).
Part 2
But even while these lines were written, the shadow-desk underwent another ghostly transformation. The tiny specks which were supposed to be its ultimate constituents turned out to be not "things" but processes-rather analogous to the vibrations of wind instruments. These "matter-waves" were first postulated by the Prince de Broglie - a lover of chamber music-to get over the difficulties into which the Bohr model of the atom had run; the mathematical theory of "wave mechanics" was shortly afterwards formulated by the Austrian Erwin Schrodinger,* and given its final form by the Englishman Paul
Dirac.
* De Broglie got his Nobel Prize in 1929, Schrodinger in 1931. Both played a part in my life. As a foreign correspondent in Paris I had the privilege of obtaining the first interview with de Broglie a few hours after he got the prize. As a result of that interview, I was appointed Science Editor of the Ullstein chain of Continental newspapers, for whom I worked at the time. Schrodinger I knew first in Berlin before the war; then in 1957 we met again and became close friends; until his death in 1961 we both spent the summer months in the Tyrolean mountain village of Alpbach. Owing to Schrodinger's presence, Alpbach became a place of pilgrimage for theoretical physicists.
But, as already said, if the constituents of matter behaved as unsubstantial waves, they also behaved in other circumstances as massive particles. "The electron", de Broglie proclaimed, "is at once a corpuscle and a wave"(6). This dualism, which is fundamental to modern physics, Bohr called the "Principle of Complementarity". "Complementarity" became a kind of credo with the so-called "Copenhagen School" - the dominant school in theoretical physics founded by Bohr. Heisenberg, one of the pillars of that school, commented: "The concept of complementarity is meant to describe a situation in which we can look at one and the same event through two different frames of reference. These two frames mutually exclude each other, but they also complement each other, and only the juxtaposition of these contradictory frames provides an exhaustive view of the appearances of the
phenomena"(7). In another place lie made a remark which illuminates one of the reasons for our present excursion into nuclear physics: "What the Copenhagen School calls complementarity accords very neatly with the Cartesian dualism of matter and mind"(8).
The same idea was expressed earlier on by Wolfgang Pauli, another giant of the quantum theory, about whom we shall hear more
later:
The general problem of the relationship between mind and body, between the inward and the outward, cannot be said to have been solved by the concept of psycho-physical parallelism postulated in the last century. Modern science has perhaps brought us nearer to a more satisfactory understanding of this relationship, by introducing the concept of complementarity into physics itself. It would be the more satisfactory solution if mind and body could be interpreted as complementary aspects of the same
reality(9).
This, together with the constant emphasis on the theme "atoms are not things"; "on the atomic level the objective world ceases to exist", is suggestive of that post-materialistic trend in modern physics which enticed many physicists into a flirtation with parapsychology - or at least into a tolerant attitude towards it. The connection will become clearer after a few more glimpses at the Wonderland of elementary particles.
Part
3
The field equations of the electron, which treated the constituents of the material world as wave-functions, were beautifully confirmed by experiment. The theory worked. But it worked at the price of accepting its inherent contradictions. The new term "complementarity" became another verbal raft for the mind at sea. When an electron collided with another particle, it behaved more or less like a tiny cannon ball. But when an electron was fired at a screen with two holes in it, it produced the characteristic interference patterns which result when two wave-fronts meet (e.g. after dropping two stones into a pond). Are we to conclude that the single electron passed through
both holes at the same time? Sir George Thomson, one of those who performed this now classic experiment, commented in his 1960 Presidential Address to the British Association: "[Commonsense would make one expect that] if a particle crosses a flat screen with two holes in it, it must have gone through one to the exclusion of the other. This is not true of an electron"(10)*. Sir Cyril Burt wrote about this fundamental paradox in more caustic terms: "If we attempt to describe the apparent behaviour of a single electron when fired at a thin screen of metal containing two minute holes, we should be constrained to infer that the particle passed through the screen in two places at once - a feat which has never yet (as far as I am aware) been performed by the ghosts of either folklore or psychical research"(11).
* One may add for the sake of piquancy that it was Sir George Thomson's father - Sir Joseph J. Thomson - who in the late 1890's discovered the electron; and that he was one of the earliest members of the Society for Psychical Research.
The alternative explanation was that the electron, while passing through the two holes, transformed itself from a corpuscle into a wave; while in other situations it sort of "condensed" from a wave into a corpuscle. But that of course is just playing with words. The only certainty gained was that the elementary constituents of matter - electrons, protons, even whole atoms - could behave like waves when they did not happen to behave like particles.
Though the constituents of matter could be described with great mathematical accuracy as patterns of vibrations, the question remained-what was it that vibrated? On the one hand, these matter-waves produced physically real phenomena, such as interference patterns on a screen, or the currents in a transistor radio. On the other hand, the whole conception of matter-waves excludes by definition any medium with physical attributes as a carrier of the waves. A wave is movement; but what is that something that moves, producing the shadows on Eddington's shadow-desk? Short of calling it the grin of the Cheshire Cat, it was named the "psi field" or "psi function". Henry Margenau, Professor of Physics at Yale University, recently
commented:
Towards the end of the last century the view arose that all interactions involved material objects. This is no longer held to be true. We now know that there are fields which are wholly non-material. The quantum mechanical interactions of physical psi fields interestingly and perhaps amusingly the physicist's psi has a certain abstractness and vagueness of interpretation in common with the parapsychologist's psi these interactions are wholly non-material, yet they are described by the most important and the most basic equations of present-day quantum mechanics. These equations say nothing about masses moving; they regulate the behaviour of very abstract fields, certainly in many cases non-material fields, often as tenuous as the square root of a
probability(12).
Yet the paradox of the physicist's psi field as an immaterial substratum of matter is merely a more esoteric repetition of the earlier paradoxes of the electro-magnetic and gravitational fields. Light, and all other electromagnetic radiations, including the domesticated radio waves of the mass media, display the same dual character of little pellets of concentrated energy-photons - and of waves in a non-medium devoid of any physical properties. It was once called the ether, but the term was dropped as meaningless, since a medium devoid of physical properties is not a medium. The term "field" was then introduced as another verbal raft, to refer to the de-materialised ether. Mass had already been shown to be the equivalent of concentrated packages of energy, according to Einstein's formula E =
mc2 (which yielded the atom bomb as a side-product); and in the general theory of relativity, mass, inertia and gravity had all been reduced to stresses, warps or kinks in empty, multi-dimensional space. The non-things of quantum theory and wave mechanics are thus not isolated curiosities in modern physics, but the culmination of a development which started towards the end of the last century. Sir James Jeans summed it up in a memorable passage in his Rede
Lectures:
Today there is a wide measure of agreement, which on the physical side of science approaches almost to unanimity, that the stream of knowledge is heading towards a non-mechanical reality; the universe begins to look more like a great thought than like a great
machine(13).
The second half of this sentence, after the semi-colon, might strike one as a
non sequitur or just a poetic metaphor. But the idea goes deeper. The contents of conscious experience have no spatio-temporal dimensions; in this respect they resemble the non-things of quantum physics which also defy definition in terms of space, time and substance - or, to quote Jeans again, can only be described "by going outside space and time". But the unsubstantial contents of consciousness are somehow linked with the substantial brain; and the physicist's unsubstantial psi fields are somehow linked with the substantial aspects of material particles. This is the parallel implied in Heisenberg's remark that the Copenhagen complementarity of corpuscle and wave, and the Cartesian dualism of matter and mind, agree with each other "very neatly"; and in Jeans' remark that the universe looks more like a thought than a machine. "More" and not "equally" - because both in Einstein's cosmos and the sub-atomic micro-cosmos, the non-substantial aspects dominate; in both, matter dissolves into energy, energy into shifting configurations of something unknown. Eddington summed it up in his epigram: "The stuff of the world is mind-stuff." The hard, tangible appearance of things exists only in our medium-sized world measured in pounds and yards, to which our senses are attuned. On both the cosmic and the sub-atomic scale this intimate, tangible relationship turns out to be an
illusion*.
* I cannot resist quoting another illuminating footnote from Sir Cyril Burt's essay on "Psychology and Parapsychology":(14)
"How remote the basic constructs of modern physics are from the observable contents of sensory experience is shown by the history of 'energy' and Einstein's unexpected identification of it with 'matter' or 'mass' ... A psychologist may be permitted to suggest that the old distinction between matter and energy resulted from the way biological needs determined the evolution of our senses. Our tactile perception of the gravitational effects of mass (e.g. a grain of sand falling on the skin) requires a stimulus of at least 0.1 gram, say about 10-20 ergs; the kinaesthetic sense (e.g. lifting a weight) is coarser still. On the other hand, the eye in rod-vision is sensitive to less than 5 quanta of radiant energy, about 10-10 ergs or rather less. In detecting energy therefore man's perceptual apparatus is 1030 times more sensitive than it is in detecting mass. Had the perception of mass been as delicate as the perception of energy, the identity of the two would have seemed self-evident instead of paradoxical. When seeing light we should at the same time have
felt the pressure or impact of the photons; and mass and energy would from the outset have been regarded as merely two different ways of perceiving the same thing..."
One may add that if our sense of touch were as delicate as our vision, Eddington's solid desk would be nearly (though not quite) transformed into the shadow-desk.
Part
4
In the early 1930's the number of known "elementary particles", which were supposedly the ultimate constituents of matter, was three: the negatively charged electron, the positively charged proton and the chargeless neutron. Protons and neutrons constituted the atomic nucleus, in which practically all the mass of the atom was concentrated; the revolving electrons - or electron-waves - constituted its outer shells. By today we know about a hundred elementary particles, either originating in cosmic radiation or produced in the laboratory. Some of them are extremely short-lived - lasting no longer than an infinitesimal fraction of a second; others, like the photon, have a virtually unlimited life-span. Some of these particles are very odd indeed - one of their quantitative attributes is actually referred to by the technical term "strangeness". Other terms in the vocabulary of modern physics are even odder. M. Gell-Mann has proposed a theory of elementary particles which, with acknowledgments to the Buddha, he called "the eightfold way"; and which enabled him to predict the discovery of yet another previously unknown particle called the omega minus - for which he got the Nobel Prize in 1969. Gell-Mann and his co-workers have even suggested that the "elementary particles" may in fact not be elementary at all, but may consist of even more elementary entities which they decided to call "quarks" - with acknowledgments to James Joyce in
Finnegan's Wake*. At the time of writing, these hypothetical entities have not, or not yet, been discovered; but "hunting the quark" has become accepted slang in physics laboratories. All of which goes to indicate that theoretical physicists are well aware of the surrealistic nature of the world they have created.
* Quark in German means curds or soft cheese, mostly of an evil-smelling sort.
But it is also a world of great mystery and beauty, reflected in those fantastic photographs of events in the bubble-chamber, which show the trajectories of unimaginably small particles, moving at unimaginable speeds in curves and spirals, colliding, recoiling or exploding and giving birth to other particles or wavicles. The actors in this pageant are invisible, but they leave trails, rows of tiny bubbles in a liquid, loosely comparable to the condensation trails of high-flying jet planes - except that these tracks are sharp, thin lines whose length, angles and curvatures can be measured with sufficient exactitude to determine a particle's energy, speed, electric charge, and so on. This technique enables the physicist to observe the unthinkable - the transformation of mass into energy and of energy into mass. When a photon, a concentrated "package of light", without rest-mass, flies past an atomic nucleus, the photon is converted into an electron and a positron*, both of which have mass, or even into two pairs of them. Vice versa, when an electron and a positron meet they destroy each other, converting their joint masses into high-energy gamma rays. To have penetrated to this depth below the world of appearances is one of the greatest triumphs of human ingenuity. Though the physicists themselves keep warning us that the ghosts we find down there elude the grasp of our understanding, at least we can measure their footprints in the bubble-chamber.
* An electron with a positive charge or anti-electron - see below.
Part
5
Of all the bewildering elementary particles in the physicist's inventory, the most ghost-like is the so-called neutrino. Its existence was predicted in 1930 by Wolfgang Pauli on purely theoretical grounds, but it was not until 1956, more than twenty-five years later, that actual neutrinos, emanating from the Atomic Energy Commission's huge nuclear piles on the Savannah River, were trapped in the laboratory by F. Reines and C. Cowan. The reason why it took so long to detect them is that the neutrino has virtually no physical properties: no mass, no electric charge, no magnetic field. It is not attracted by gravity, nor captured or repelled by the electric and magnetic fields of other particles while flying past them. Accordingly, a neutrino originating in the Milky Way, or even in some other galaxy, and travelling with the speed of light, can go clean through the solid body of the earth as if it were so much empty space - Eddington's desk, in fact. A neutrino can be stopped only by a direct, head-on collision with another elementary particle, and the chances of such a direct collision, while passing through the whole earth, are estimated at about one in ten thousand million.* "Fortunately", as the science writer Martin Gardner remarks, "there are enough neutrinos around so that collisions
do occur, otherwise the neutrino would never have been detected. As you read this sentence, billions of neutrinos, coming from the sun and other stars, perhaps even from other galaxies, are streaming through your skull and brain"(15). Not only physicists were excited by the discovery of the neutrino. John Updike, the novelist, wrote a poem to celebrate it, called 'Cosmic Gall':(16)
* Reines and Cowan, the discoverers of the neutrino, have in recent years established laboratories in the depths of salt-mines and goldmines to trap pure neutrino showers, uncontaminated by other particles from space which cannot penetrate to those
depths.
Neutrinos, they are very small.
They have no charge and have no mass
And do not interact at all.
The earth is just a silly ball
To them, through which they simply pass,
Like dustmaids down a drafty hall
Or photons through a sheet of glass
They snub the most exquisite gas,
Ignore the most substantial wall,
Cold-shoulder steel and sounding brass,
Insult the stallion in his stall,
And, scorning barriers of class,
Infiltrate you and me!
Like tall and painless guillotines, they fall
Down through our heads into the grass...
To the unprejudiced mind, neutrinos have indeed a certain affinity with ghosts - which does not prevent them from existing. This is not just a whimsical metaphor. The absence of "gross" physical properties in the neutrino, and its quasi-ethereal character, encouraged speculations about the possible existence of other particles which would provide the missing link between matter and mind. Thus the eminent astronomer V. A. Firsoff suggested that "mind was a universal entity or interaction of the same order as electricity or gravitation, and that there must exist
a modulus of transformation, analogous to Einstein's famous equality E=
mc2, whereby 'mind stuff' could be equated with other entities of the physical world"." He further suggested that there may exist elementary particles of the mind-stuff, which he proposed to call "mindons", with properties somewhat similar to the
neutrino's:
The universe as seen by a neutrino eye would wear a very unfamiliar look. Our earth and other planets simply would not be there, or might at best appear as thin patches of mist. The sun and other stars may be dimly visible, in as much as they emit some neutrinos ... A neutrino brain might suspect our existence from certain secondary effects, but would find it very difficult to prove, as we would elude the neutrino instruments at his disposal.
Our universe is no truer than that of the neutrinos - they exist, but they exist in a different kind of space, governed by different laws ... In our space no material body can exceed the velocity of light, because at this velocity its mass and so inertia becomes infinite. The neutrino, however, is subject neither to gravitational nor to electro-magnetic fields, so that it need not be bound by this speed limit and may have its own, different time. It might be able to travel faster than light, which would make it relativistically recede in our time scale.
... From our earlier analysis of mental entities, it appears that they have no definite locus in so-called "physical", or, better, gravi-electromagnetic, space, in which respect they resemble a neutrino or, for that matter, a fast electron. This already suggests a special kind of mental space governed by different laws, which is further corroborated by the parapsychological experiments made at Duke University and elsewhere ... It seems ... that this kind of perception involves a mental interaction, which is subject to laws of its own, defining a different type of
space-time(18).
Firsoff's "mindon," is however, a rather primitive model marred by that atomistic interpretation of mental events which psychology is at long last beginning to outgrow. A more sophisticated approach has been suggested by Sir Cyril Burt, whose "psychons"* have configurational rather than particle character, but he did not elaborate on it in detail. The most recent attempts to provide a link between the psi function of quantum mechanics and the psi phenomena of parapsychology were made by the physiologist Sir John Eccles and the mathematician Adrian Dobbs. But they require a preliminary excursion to even wilder shores of modern physics than we have glimpsed so far.
* The term psychon was originally suggested by Whately Carington.
Part
6
In 1931, Paul Adrian Maurice Dirac of Cambridge proposed a theory which would have been rejected as outright crankish if its author had not been one of the outstanding physicists of his time, whose greatest previous achievement (for which he got the Nobel Prize in 1933) had been the unification of Einstein's theory of relativity and Schrodinger's wave mechanics. However, the unified theory ran into new difficulties, which Dirac sought to overcome by postulating that space was not really empty, but filled by a bottomless sea of electrons with
negative mass (and consequently negative energy). Negative mass is of course beyond human imagination; if anything can be said of a particle of this kind it is that if you try to push it forward, it will move backward, and if you blow at it, it will be sucked into your lungs. Since, according to the hypothesis, all available locations in space are uniformly filled with minus-energy electrons, they do not interact, and do not manifest their existence. However, occasionally a high-energy cosmic ray may hit one of these ghost-electrons and impart its own energy to it. As a result, the ghost electron will leap out of the sea, as it were, and become transformed into a normal electron with positive energy and mass. But there is now a "hole", or bubble, left in the sea where the electron had been. This hole will be a negation of negative mass: it will have positive mass. But it will be also a negation of the former occupant's negative electric charge: it will have positive charge. The hole in the cosmic ocean would in fact be, Dirac predicted in 1931, "a new kind of particle unknown to experimental physics, having the same mass as and opposite charge to an electron. We may call such a particle an anti-electron."
But the anti-electron, he further predicted, would be short-lived. Very soon a normal electron would be attracted by the "hole", fall into it, and the two particles would annihilate each other, de-materialising in a flash of high-energy rays.
The theory sounded so wild that Niels Bohr wrote a spoof on it called "How to Catch Elephants". With the schoolboy humour which seems to be a characteristic of great physicists, he proposed that big-game hunters should erect at a watering spot frequented by elephants a large poster which briefly summarises Dirac's theory. "When the elephant, who is a proverbially wise animal, comes to have a drink of water, and reads the text on the poster, it will become spellbound for several minutes." Profiting from its trance-like state, the hunter will slip out from his hiding place, tie the elephant's legs with solid ropes, and ship him to the zoo in Copenhagen*.
* I owe this story to George Gamow(19), and may as well quote here another of Gamow's anecdotes:
"Another example of Dirac's acute observation has a literary flavour. His friend Peter
Kapitza, the Russian physicist, gave him an English translation of Dostoyevsky's
Crime and Punishment.
"'Well,how do you like it?' asked Kapitza when Dirac returned the book.
"'It is nice,' said Dirac, 'but in one of the chapters the author made a mistake. He describes the sun as rising twice on the same day.' This was his one and only comment on Dostoyevsky's novel."(20)
And yet ... one year after the publication of Dirac's paper, Carl D. Anderson, working at the California Institute of Technology, was studying the tracks of cosmic-ray electrons in the bubble-chamber, and found that when passing through a strong magnetic field some of them were deflected in a direction opposite to that which normal electrons with a negative charge should follow. Anderson concluded that his weird particles must be positively charged electrons, and called them positrons. They were in fact the "anti-electrons" or "holes" predicted in Dirac's paper - which Anderson had never read.
Since the discovery of the anti-electron, physicists have found - or produced in their laboratories - anti-particles corresponding to every known particle. The fifty particles known today and their fifty "antis" are in every respect alike, except that they have opposite electric charges, magnetic moments and opposite "spin" and "strangeness"*. But anti-particles are, under normal conditions, very rare: they are either produced by radiation from outer space or by bombarding matter with extremely powerful projectiles; and they are, as already said, very short-lived, because whenever an anti-particle meets its terrestrial
alter ego, or Doppelganger, they annihilate each other. However, it is considered quite possible that other galaxies are composed of anti-particles, combining into anti-matter; and furthermore, that some spectacular celestial events, such as super-novae or powerful invisible X-ray sources, originated in the collision and mutual annihilation of clouds of matter and anti-matter. These apocalyptic perspectives have become a favourite subject of science-fiction writers - and have also inspired some more quantum poetry. In 1956, Edward Teller (the "father of the hydrogen bomb") gave a lecture in which he enlarged on the explosive consequences of matter getting into contact with anti-matter. A Californian physicist, Harold P. Furth, thereupon wrote a poem which the
New Yorker printed in November 1956:(21)
* In kindness to the reader I shall not attempt to explain these terms.
Well up beyond the tropostrata
There is a region stark and stellar
Where, on a streak of anti-matter,
Lived Dr. Edward Anti-Teller.
Remote from Fusion's origin,
He lived unguessed and unawares
With all his anti-kith and kin,
And kept macassars on his chairs.
One morning, idling by the sea,
He spied a tin of monstrous girth
That bore three letters: A.E.C.*
Out stepped a visitor from Earth.
Then, shouting gladly o'er the sands,
Met two who in their alien ways
Were like lentils. Their right hands
Clasped, and the rest was gamma rays.
*
Atomic Energy Commission.
Part
7
Yet the theory of an ocean of particles of negative mass, though sufficiently striking to mesmerise an elephant, was regarded with distaste by many physicists. Not because it sounded fantastic; but because it could neither be verified nor refuted by any conceivable method; and it had a suspicious affinity with the nineteenth-century ether. The anti-particles were accepted facts, but physicists were looking for a more elegant theory to account for their behaviour.
One such theory was suggested in 1949 by Richard Phillipps Feymnan, also of the California Institute of Technology. He proposed that the positron is nothing but an electron which, for a while, is
moving backwards in time, and that the same explanation holds for other antiparticles. On the so-called Feymnan diagrams, which soon became household articles to physicists, one axis represents time, the other space; particles can move forward and backward in time, and a positron travelling, like all of us, into the future behaves exactly as would an electron travelling momentarily into the past. The time reversals postulated by Feymnan are short-lived, because in our world anti-particles are short-lived; whether in a galaxy consisting of anti-matter time would permanently flow backward relative to ours is a matter of speculation. But as far as terrestrial physics goes, Feymnan's concept of time reversal proved so productive that in 1953 he received the Albert Einstein Medal and in 1965 the Nobel Prize. The philosopher of science, Hans Reichenbach, wrote that Feymnan's theory represented "the most serious blow the concept of time has ever received in
physics"(22).
Part
8
Yet the history of science has shown over and over again that the fact that a theory "works" and produces tangible results does not prove that the underlying assumptions are correct; and Feymnan's theory presents formidable logical difficulties, even by the permissive standards of modern
micro-physics*. Among various attempts to overcome them is the hypothesis, already mentioned, by Adrian
Dobbs**, which introduces two time dimensions, instead of one. A five-dimensional universe with three spatial and two temporal dimensions had already been proposed by Eddington and others; but Dobbs' theory contains refinements which take into account the unpredictability and indeterminacy of the future in quantum physics. Accordingly, the arrow of time, progressing along the second time dimension, moves through a probabilistic, instead of a deterministic, world; and it resembles less an arrow than a wave front. However, the main interest of Dobbs' hypothesis lies in his attempt to provide a physicalistic explanation of telepathy and precognition, more sophisticated than any offered before. So sophisticated in fact that it is almost impossible to understand without some working knowledge of quantum theory.
* See, for instance, G. J. Whitrow's criticism in
The Voices of Time, ed. J. T. Fraser, London, 1968.
** Adrian Dobbs, who died of an accident while this essay was being written, was a brilliant Cambridge mathematician and physicist engaged in top secret work related to national defence. This was disclosed in a moving obituary by Professor C. D. Broad in the
Journal of the Society for Psychical Research, December, 1970.
The gist, however, regarding precognition is that the anticipation of future events follows the second time dimension, where "objective probabilities" play the same part as causal relations in classical physics. In Dobbs' own words he proposes "a second time dimension in which the objective probabilities of future outcomes are contained as compresent dispositional factors, which incline or predispose the future to occur in certain specific ways"(23). This has the initial advantage of getting round the old logical paradox that foreknowledge of a future event would imply the possibility of interfering with that event and thus nullifying the foreknowledge.
Dobbs uses the term "pre-cast" instead of "precognition", to indicate that it refers not to prophecy, but to the perception of the probabilistic factors in a system which predispose it towards a given future state. But these pre-casts are not based on guesswork, nor on rational inferences, since the "dispositional factors" of the system cannot be observed or deduced. Information about them is conveyed to the subject by hypothetical messengers which Dobbs calls "psitrons" and which operate in his second time dimension. They are particles with rather startling attributes, but not much more startling than Pauli's neutrino, Dirac's minus-mass electrons, or Feynman's electrons travelling back in time-each of which brought in a Nobel Prize. Dobbs' concept of the psitron is, in fact, the joint product of current trends in quantum theory and brain research. It has
imaginary mass (in the mathematical sense)* and thus, according to Relativity Theory, can travel faster than light indefinitely, without loss of (imaginary) momentum.
* Imaginary numbers have negative squares, although by definition the square of any natural number, whether negative or positive, must be positive ("minus times minus makes plus"). But they are useful tools in quantum physics, where they are equivalent to introducing an added dimension besides ordinary energy, mass or time.
In modern quantum theory processes involving negative or imaginary mass are all in a day's work, so to speak. Professor Margenau of Yale University has given us a picturesque description of this state of
affairs:
At the forefront of current physical research, we find it necessary to invoke the existence of "virtual processes" confined to extremely short durations. For a very short time, every physical process can proceed in ways which defy the laws of nature known today, always hiding itself under the cloak of the principle of uncertainty. When any physical process first starts, it sends out "feelers" in all directions, feelers in which time may be reversed, normal rules are violated, and unexpected things may happen. These virtual processes then die out and after a certain time matters settle down again(24)
[compressed].
Professor Bohm of Birkbeck College, University of London, emphasises the same point in his book
Quantum Theory.
The preceding description [of certain quantum phenomena] involves the replacement of the classical notion that a system moves along some definite path, by the idea that under the influence of the perturbing potential the system tends to make transitions in all directions at once. Only certain types of transitions can, however, proceed indefinitely in the same direction, namely those ... called real transitions to distinguish them from the so-called virtual transitions which do not conserve energy, and which must therefore reverse before they have gone too far. This terminology is unfortunate, because it implies that virtual transitions have no real effects. On the contrary they are often of the greatest importance, for a great many physical processes are the result of the so-called virtual
transitions(25).
In his paper, Dobbs quotes this passage, and
comments:
I have quoted this passage at length because the quantum theory of virtual transitions is closely related to the notion I have been suggesting, of an actual state of an entity ... being surrounded in imaginary time with an array of objective probabilities, which are not necessarily actualised, but nonetheless influence the actual course of events ... As Bohm says, we have to consider the system as, so to speak, trying out tentatively all the possible potentialities out of which one actuality emerges. Now we can picture these virtual potentialities or probability amplitudes as a swarm of particles of imaginary mass, interacting together like a frictionless
gas...(26)
This swarm, or cloud, or "patterned set" of psitrons of imaginary mass, impinging on neurons in the percipient's brain, which are in a particularly receptive condition, would transmit not only information about the
actual state of the system that emits them but also "pre-casts" of its inherently probable future state, which are already reflected in the "feelers in all directions" which it sends out. Thus the psitrons, Dobbs says, would play an analogous part to that of photons in ordinary vision - except that the psitrons would act directly on the brain, instead of the eye; that they have
imaginary rest-mass, while the photon's rest-mass is zero; and that they carry information on both
actual and virtual processes, the latter "precasting" the immediate future. If the reader finds much of this obscure, he must seek comfort in the thought that obscurity is, so to speak, built into quantum physics like the holes into a Gruyere cheese.
On the crucial question, how the hypothetical psitrons could convey information direct to the percipient's brain, short-circuiting, as it were, the sensory apparatus, Dobbs resorted to a theory advanced some years ago by Sir John Eccles. This eminent physiologist received the 1963 Nobel Prize for his pioneering work on the transmisson of nerve impulses across the synaptic junctions between brain-cells. In the last chapter of his textbook on The
Neurophysiological Basis of Mind Eccles launched what he called a "Hypothesis of the mode of operation of 'Will' on the cerebral cortex". The hypothesis is not concerned with precognition, but what it says about the interaction of mind and matter is pertinent to the subject, and I shall have to quote from it at some
length.
It is a psychological fact that we believe we have ability to control or modify our actions by the exercise of "will", and in practical life all sane men assume that they have this ability. By stimulation of the motor-cortex [of the exposed brain of patients undergoing a brain operation] it is possible to evoke complex motor acts in a conscious human subject. The subject reports that the experience is quite different from that occurring when he "willed" a movement ... In one case there was the experience of having "willed" an action, which was missing in the
other.*
* For a more detailed account of these experiments, first reported by Wilder Penfield, see
The Ghost in the Machine, pp.203-4.
It is not
here contended that all action is "willed". There can be no doubt that a great part of the skilled activity devolving from the cerebral cortex is stereotyped and automatic, and may be likened to the control of breathing by the respiratory centres. But it is contended that it is possible voluntarily to assume control of such actions, even of the most trivial kind, just as we may within limits exercise voluntary control over our breathing....
An important neurophysiological problem arises as soon as we attempt to consider in detail the events that would occur in the cerebral cortex when, by the exercise of "will", there is some change in response to a given situation ....
(21)
Eccles then proceeds to work out a concise theory of how a minute "will-influence", affecting
a single neuron in the cortex, could trigger off very considerable changes in brain activity. The trigger-action would affect neurons which are "critically poised", as he puts it, i.e. in unstable equilibrium, just below the threshold of discharging a nerve impulse.* In view of the fact that there are some forty thousand neurons packed together per square
millimetre (approximately 1/700 square inch) of the cerebral cortex, and that each neuron has several hundred synaptic connections with other neurons, we have here a network of such density and complexity that
in the active cerebral cortex within twenty milliseconds, the pattern of discharge of even hundreds of thousands of neurons would be modified as a result of an "influence" that initially caused the discharge of merely one neuron ...
Thus, the neurophysiological hypothesis is that the "will" modifies the spatio-temporal activity of the neuronal network by exerting spatio-temporal "fields of influence" that become affected through this unique detector function of the active cerebral
cortex(30).
* As a matter of curiosity I may be permitted to mention here that in an earlier book -
The Yogi and the Cominissar, published in 1943 - I made a suggestion which seems in some respects to anticipate Eccles' theory of the "will" acting on "critically poised" brain cells, thus giving rise to conscious
actions:
"Volition may be regarded as the psychological aspect or projection of the interplay of impulses
and inhibitions. If this interplay takes place on the conscious level it is experienced as a not enforced, not inevitable process of choice. This subjective experience of freedom is the stronger the closer the process to the focus of attention. Actions resulting from processes on the pre-conscious fringes are experienced as 'absent-minded' semi-automatic doings, and from extra-conscious processes as fully automatic.
"The experience of freedom resulting from processes in the focus of attention is probably synonymous with consciousness itself. Its essential characteristic is that the process is experienced as working from inside outwards instead of from outwards in; it seems determined from the subject's core and not by outward environment. On the psychological plane the experience of freedom is as much a given datum or 'reality' as are sense perceptions or the feeling of pain ...(28) Incidentally, the state of 'precarious balance' which characterises the emergence of experienced freedom is also characteristic of the original instability of organic molecules and other emergent biological levels"(29).
Eccles is a determined opponent of the positivist argument that while "brain" is a reality, "mind" is a fiction - a ghost in the
machine:
It will be objected [he writes] that the essence of the hypothesis is that mind produces changes in the matter-energy system of the brain and hence must be itself in that system ... But this deduction is merely based on the present hypotheses of physics. Since these postulated "mind-influences" have not been detected by any existing physical instrument, they have necessarily been neglected in constructing the hypotheses of physics ... It is at least claimed that the active cerebral cortex could be a detector of such "influences", even if they existed at any intensity below that detectable by physical instruments. It would appear that it is the sort of machine a "ghost" could
operate(31).
So far Eccles has been discussing the action of individual minds on their "own" brains. In the concluding sections of his book, however, he lifts this restriction and includes ESP and PK into the theory. He accepts the experiments of Rhine, Thouless, Soal, etc. as evidence for a generalised "two-way traffic" between mind and matter, and for a direct traffic between mind and mind. He believes that ESP and PK are weak and irregular manifestations of the
same principle which allows an individual's mental volition to influence his own material brain, and the material brain to give rise to conscious experiences. He also reminds us of an unduly neglected hypothesis, which Eddington formulated in 1939, of a "correlated behaviour of the individual particles of matter, which he assumed to occur for matter in liaison with mind. The behaviour of such matter would stand in sharp contrast to the uncorrelated or random behaviour of particles that is postulated in physics"(32).
Let us now return to Dobbs. Eccles seems to have deliberately abstained from giving any indication of the supposed nature of those "influences" or "influence-fields" which are meant to serve as vehicles for the traffic between matter and mind, or mind and mind. Dobbs proposed to provide such a carrier by the psitron which, when it impinges on the "critically poised" neurons in the brain, can trigger off "a cascade or chain reaction" of neural events.
Although Dobbs' hypothesis includes telepathy, clairvoyance and precognition, it says nothing about the problem of how mind and brain interact in one and the same ordinary person - which was Eccles' starting point.
Dobbs is not directly concerned with the mind-body problem; he takes it for granted that certain processes in the brain give rise "to certain states of awareness" and that applies regardless of whether the brain processes in question were induced by extra-sensory, or common sensory, perception. The distance in space which the psitron has to travel is irrelevant - as it is irrelevant to neutrinos.
Thus we arrive at the paradoxical conclusion that physicalistic theories such as Adrian Dobbs', however ingenious, may explain the "extra" in extra-sensory perception, but leave the basic mystery of ordinary, sensory perception where it was before. But at least these theories, based on assumptions which sound weird but hardly more weird than those of modern physics, go a long way towards removing the aura of superstition from the "extra" in extra-sensory perception. The odour of the alchemist's kitchen is replaced by the smell of quark in the laboratory. The rapprochement between the conceptual world of parapsychology and that of modern physics is an important step towards the demolition of the greatest superstition of our age - the materialistic clockwork universe of early-nineteenth-century physics. "To assert that there is
only matter and no mind", Firsoff wrote, "is the most illogical of propositions, quite apart from the findings of modern physics, which show that there is no matter in the traditional meaning of the term"(33). Or, once more, Sir Cyril Burt (who has an irresistible effect on writers suffering from "Quoter's
Itch"):
And so we arrive at the current conception of the brain as a kind of computer, and of human beings as mere conscious automata., "If you think we are waxworks," said Tweedledum to Alice, "you ought to pay." And contemporary psychology has had to pay a heavy price for adhering to this mechanistic doctrine. It makes nonsense, not only of parapsychology, but (as practical psychologists have long been protesting) of every branch of applied psychology - criminology, psychotherapy, educational and vocational guidance, and of all moral or aesthetic aspirations and values. As a theory of the relation of body and mind, [materialism] rests on a glaring inconsistency ... In a purely mechanical world of cause and effect, ruled by the law of the conservation of energy, no "phenomenon" ... could possibly appear without some appropriate cause. Within the nervous system, therefore, so [it was] ... suggested, energy must in some inexplicable fashion be "transformed" into consciousness. The chemistry of the brain must "generate" it, much as the liver generates bile. How the motions of material particles could possibly "generate" this "insubstantial pageant" remained a mystery. Any such process would obviously be, not physical, but psychophysical; so that the perfection of a purely physical universe was already rudely
violated(34).
Part
9
At the beginning of this essay I suggested that the seemingly fantastic propositions of parapsychology appear less preposterous in the light of the truly fantastic concepts of modern physics. My purpose in describing Dobbs' theory* in the context of quantum mechanics was merely to illustrate this point - without any claim that the theory is correct, or even on the right lines; I could have cited other hypotheses to make the same point. Physicists are not shy, as we saw, of producing
ad hoc hypotheses - or speculations - to accommodate newly discovered phenomena which do not fit into the existing framework. The Greeks knew the electrical properties of amber - or
elektron - but were not interested. For some two thousand years nobody was interested. When, in the seventeenth century, experimenting with electricity became fashionable, previously undreamt-of phenomena were discovered, and scientists vied in proposing hypotheses to account for them - postulating effluvia, liquid fires, currents, fields, without turning a hair. Magnetism and gravity had a similar history: when Kepler suggested that the tides are due to attractive forces emanating from the moon, Galileo shrugged the idea off as an "occult fancy" because it involved action-at-a-distance and thus contradicted the "laws of nature"; but that did not deter Newton from postulating universal gravity.
"Hypothesis non fingo" is perhaps the most shocking piece of hypocrisy ever uttered by a great scientist.
* At the end of Dobbs' main paper(35) he proposes an experimental programme, including a certain type of EEG test during ESP experiments, which, he maintained, would confirm or refute his theory. It is to be hoped that in spite of his untimely death, the experiments will be made (although for reasons too technical to explain, I would predict a negative result).
This does not mean that hypothesis-making is a free-for-all. To produce live rabbits out of a hat needs a skilled magician. Quantum physics may be mad, but it has method, and it works. I talked earlier on of a negative rapprochement between quantum physics and ESP, in so far as the surrealistic concepts of the former make it easier to suspend disbelief in the latter; if the former is permitted to violate the "laws of nature" as they were understood by classical physics a century ago, the latter may claim the same right. But to stress the point once more, this is merely a negative agreement, a shared disregard for ancient taboos, for a mechanistic world-view which has become an anachronism.
That is all to the good. There are, however, phenomena in parapsychology which no physicist, however open minded, can willingly accept on face value: I mean PK -
psychokinesis.
The "extra" bit in extra-sensory perception may quite possibly become in the not too distant future amenable to theoretical treatment in terms of quantum physics enriched by new "fields" added to the existing ones, and new types of "interactions" added to the existing repertory of
four*. But such optimism seems less justified when it comes to psychokinesis. Dobbs is silent about it, so is
Margenau, and - within my limited knowledge of parapsychological literature - I am unaware of any serious attempt at a physicalistic explanation of how a mental effort could influence the motions of rolling dice. The reason is simple: ESP and PK are operating in different dimensions; and just as the rigid mechanical laws of the macroscopic world do not apply to micro-physics, so the freedom enjoyed in the realm of micro-physics does not apply to the macroscopic level. An atom is 'Tree" to do this or that within Heisenberg's indeterminacy relation, and all our statements about it refer to probabilities, not to certainties. But according to the law of large numbers, in a macroscopic body of trillions of atoms, the deviations cancel out, the sum of probabilities results in practical certainty, and the old taboos retain their
validity**. Thus when an ESP message in the shape of mindons, psitrons or what-have-you impinges on a "critically poised" neuron, it operates on the quantum indeterminacy level and can do wonders, so to speak. But this process is not reversible. You cannot influence the progress of a macroscopic body like a rolling die, by micro-physical particles or wavicles of imaginary mass. Thus the law of large numbers, which lends such authority to the evidence for ESP, is at the same time the main obstacle to any physicalistic explanation of
PK***.
* Contemporary physics knows four types of interaction: the "strong" and "weak" nuclear interactions; the electro-magnetic and the gravitational. Each obeys its own set of laws.
** To illustrate this point, the uncertainty attaching to the whereabouts of a single electron in a hydrogen atom is "smeared" over the whole length of its "planetary orbit". But the velocity of a small buckshot is uncertain only within about twelve inches per century, and the uncertainty of its position is only the size of the diameter of the atomic nucleus(36).
*** The importance of Helmut Schmidt's revolutionary experiments with electronic equipment, discussed earlier on, lies precisely in the fact that they operate on the quantum level. But you cannot extrapolate from there to dice.
But this does not mean that the evidential value of the macroscopic PK experiments, by Rhine and others, is to be disregarded. It only means that, though we have to accept the evidence, we have to renounce any reasonable hope of a physical explanation, even in terms of the most advanced and permissive quantum mechanics.
The same dilemma confronts us as we turn to a type of phenomenon which has puzzled man since the dawn of mythology: the disruption of the humdrum chains of causal events by coincidences of an improbable nature, which are not causally related yet appear highly significant. Any theory which attempts to take such phenomena seriously must necessarily involve an even more radical break with our traditional categories of thought than the pronunciamentos of
Heisenberg, Dirac or Feynman. It is certainly no coincidence that it was Wolfgang Pauli - father of the neutrino and of the
"Pauli Principle", a cornerstone of modern physics-who outlined such a theory, in collaboration with C. G. Jung.
The Jung-Pauli theory of "Synchronicity", conceived by a physicist and a psychologist, both eminent in their fields, represents perhaps the most radical departure from the world-view of mechanistic science in our time. Yet they had a precursor, whose ideas had a considerable influence on Jung: the Austrian biologist Paul
Kammerer, a wild genius who committed suicide in 1926, at the age of
forty-five.
References
1.
Oppenheimer (1966), p.40.
2.
Heisenberg (1969), pp.63-4, 155.
3.
Russell (1927), pp. 163, 165.
4.
Quoted by Burt (1967), p.80.
5.
Eddington (1928), introduction.
6.
Quoted by Heisenberg (1969), pp.101 et seq.
7.
Heisenberg, op. cit., p.113.
8.
Quoted by Burt (1968), p.36.
9.
Pauli (1952), p.164.
10.
Quoted by Hardy (1965), p.256.
11.
Burt (1967), p.80.
12.
Margenau (1967).
13.
Jeans (1937), pp.122 f.
14.
Burt (1967), pp.80-1.
15.
Gardner (1967), pp.240-1.
16.
In Telephone Poles and Other Poems, 1963.
17.
Firstoff (1967), pp.102-3.
18.
Ibid., pp.105-6.
19.
Gamow (1966), p.132.
20.
Ibid., pp.121-2.
21.
10.XI.1956.
22.
Reichenbach (1956).
23.
Dobbs (1965), pp.261-2.
24.
Margenau (1967), p.217.
25.
Quoted by Dobbs (1965), p.303.
26.
Dobbs (1965), pp.303 and 305.
27.
Eccles (1953), pp.271-2.
28.
Koestler (1945), p.207.
29.
Ibid., p.227.
30.
Eccles (1953), p.276-7.
31.
Ibid., pp.283-5.
32.
Ibid., p.279.
33.
Firstoff (1967), p.52.
34.
Burt (1968), pp.34-5.
35.
Dobbs (1965), pp.333 et esq.
36.
Gamow (1966), p.111.
Note:
The
article above was taken from Arthur Koestler's 1972 book "The Roots of
Coincidence" published by Hutchinson & Co.
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