My predicament in entering University life recalls a situation in one of the Kai Lung stores. The young man Win was about to set out on a dangerous journey for which his education had been intended to prepare him. In a ceremony to mark his departure, the guests took tea while the principles of Yin's education were reviewed. Then followed a, banquet of forty-four courses. As the guests tasted each one they were told its ingredients and its manner of preparation. Finally, as Yin's name was uttered repeatedly by those present, the young man modestly stood forward and set forth his manner of thinking concerning all subjects with which he was acquainted.

I cannot promise you forty-four courses, but in compensation I will try to be more brief than Yin.

I am leaving the straightforward practice of physics in order to attempt to teach this art to younger men and women. For me, at least, it is a very appropriate exercise to ask why physics in pursued. So I propose three questions:

First, do the theories of physics describe the world as it really is? My examples may suggest that they do not.

Second, what is it that the physicist aims to do? Professor Hughes has warned me that a person's aims as judged from his actions do not always accord with the description that he might quite sincerely give of his aims, when asked. So we must examine the way in which a physicist works.

And last, where is scientific enquiry leading us?

Rather than depend entirely on my own opinions I have been conducting a small enquiry among my friends. One woman with a secretarial background, the wife of a fellow physicist, viewed the sciences with admiration and even with some awe since they were proving so powerful in revealing the structure of the world. Three other people, graduates in English. Education and Psychology, showed no admiration for physics at all; I hasten to explain that they were not of this University. They showed considerable irritation, and fear of such outcomes as nuclear weapons of war; they classed physicists as uncouth people unacquainted with the higher things of life. My fellow physicists, however, who were with me in Government employ, found the pursuit of physics interesting, particularly when their apparatus worked, or when they had applied their skill successfully to some real-life situation, or when they had hit on some promising theory. These different attitudes suggest that an enquiry is worth while.

Do The Theories Of Physics Describe The World As It Really Is?

Physics is an attempt to view the processes of the world as mechanics. Newton had striking success in devising good laws of mechanics and in lighting on the universal law of gravitation. This lead other people to suggest further ideas in the same vein. But I am asking whether physical theories are true. So Newton, is he right, or the man who believes in a flat Earth, is he right?

G. K. Chesterton remarked how difficult it was to refute the ideas of a man who believed that the Earth was flat. I think he must have tried it. I have not, and so am not skilled in flat-Earth arguments, but one may imagine oneself pointing out to the flat-Earth advocate that the Earth has no edge. He agrees; he remarks perhaps that it must be an infinite plane You then ask how it comes that the Earth has a limited area. He explains: objects increase in size as they become more remote from the Earth's true centre, which may be Wellington, with the result that the area seems to be finite though actually it is not. How then, you ask, can the Sun been seen to sink behind the bulge of the Earth? This is easy; it is, he says, an optical illusion. One does not realise it, but beams of light are repelled by the Earth and curve away from it. In consequence, when the Sun passing overhead, has reached a certain distance its beams when they reach you are travelling horizontally, and you imagine that you see the Sun just above the horizon. A little later and you are left in darkness; you have experienced the illusion of a setting Sun. At this you perhaps retire defeated.

Of course, the physics that is developed by the flat-Earth advocate in very complicated. The bending beams of light are perhaps the least complication. We treasure a useful principle that is conventionally attributed to William of Occam. For physicists it amounts to this, that if you have two alternative theories that account for the observations you should prefer the simpler one even though it may contain some unprecedented concepts. The laws of physics offered by the advocate of a flat-Earth are so very complicated that we prefer the simpler picture given by Newton. We prefer it even though the earth appears as a globe, resting on nothing But if we offer this judgement to the flat-Earth advocate he rebukes us. Scientific enquiry, he says is not a matter of convenience but of truth. He at least refuses to be misled and starting from the obvious fact that the Earth is flat, he delights indeed, in the [unclear: intrieactes] of the physics that follows So is it he that is right or Newton?

But let us put these doubts aside and be orthodox The followers of Newton met a difficulty that is sometimes called the Laplacian illusion. It is this that we most suppose that the molecules of matter, as well as the planets obey the laws of dynamics. Of course the forces acting on them may be other than gravitational. They may be electrical, but the laws will have the same inevitable character. The positions and velocities of the molecules at this present instant determine their entire future. Then does it not follow that the future is written. If yon are matter then your hopes, fears, loves, hates, indecisions and resolutions are illusionary. They happen to you true, but any notion you may have that you can influence what happens to you is quite mistaken. What is one to make of this argument? My comment is that this theory seems to give a very inadequate description of the process of living. I do not propose to suggest where the theory may have cone astray but if a theory does not adequately describe the events then so much the worse for the theory.

Physicists use numbers a great deal; they count. Kronecker said of mathematics, "God made the integers all else is the work of man." I have my suspicions about the integers. I think we invented them, too. Their very usefulness is a bad sign. The noble savage walking through the woods does not find a bow and arrow, nor a canoe, growing on a tree. He must both conceive and fabricate these useful things. Again, you will agree that counting is useful only in so far as the things that one is counting are alike. But objects or events are never quite alike though we may reckon them so for our practical purposes. When seven folk are coming for coffee one puts out seven cups. The cups may be odd; the people will certainly be odd too, in the sense that they are not alike, yet you count seven cups. Or imagine a situation in which pound notes had different values depending on their ages; one might need to purchase an article with say, three pound notes of a 1960 vintage or four notes from 1950, with a sliding scale for the years between. We think this inconvenient. We legislate that they shall all have the same exchange value. To help this way of thinking, we print them as alike as possible But different pound notes are in fact different.

One probably acquires some feeling for number at an early age. I move a muscle and find a hand. Another muscle and up comes another hand. Another muscle and up comes a foot; but perhaps I find that feet and hands are put to different uses. I clasp the hands. Each hand touches only one other and no hands are left over. This is the quality of "evenness." I disengage one hand. No pairs are left, and this is the quality of "two-ness." I say I have two hands. Yet the hands are not alike. This thumb is on the wrong side; I see the palm of one hand but the back of the other: os if I succeed in getting the thumbs right and the palms right, the fingers point in opposite directions. Indeed either hand is like the image of the other seen in a mirror, and this is a radical difference as chemists very well know. Yet I say I have two hands.

One transfers this idea of number to other things. Holding an apple in each hand I have two apples. But what if one were an orange? Could I say I had two of anything? Yes, provided that I enlarge the concept and overlook still greater differences. I can say I have two "fruit." Or suppose both were apples, but one was very small and green. Then how many apples do I have? A botanist would say "two." because each is a fertilised compound fruit of an apple tree. But a cook would deny this. He would say that the small green fruit was of no use in making an apple turnover and that for his purposes it did not count as an apple. He would say "one."

I am suggesting, you see, that there is a real world whose events we experience and that out of these experiences we make concepts, mental images, that we use in planning our actions. I am suggesting that integers belong to this world of concepts, not to the real world Perhaps in the real world there is no two of anything.

But I must return to physics. The conclusions of modern physics can seem very strange Fifty years ago physicists had to admit that a beam of light could in some circumstances behave like a train of waves and in other circumstances behave like a hail-storm of small particles. Light travelling by two slightly different paths can reunite to give darkness if the paths differ in length by the right amount. One ingeniously explains this by saying that the light waves travelling by the two paths come together "out of phase" and cancel. On the other hand, a beam of light falling on a clean metal surface causes electrons to jump out of the surface. It is difficult to see how the energy of the light can be delivered to the very small region from which each electron comes unless one can think of light as a hail of small "photons." This ambiguous behaviour had to be accepted. Forty years ago, a young physicist, Prince Louis de Broglie, suggested that the primary particles of matter would also behave in this ambiguous way. Is was soon shown that they in fact did. The fact was soon put to use. An optical microscope uses beams of light; it proved possible to make a microscope using beams of electrons; and because electron waves are so much finer than waves of visible light an electron microscope can distinguish structures one hundred times smaller in diameter. This is a tremendous technical advance, and one feels that de Broglie's picture must be right. The ambiguous behaviour has been extended in this way, that the waves occur in groups. The groups of waves is what we think of as a particle, but its structure is essentially wavelike.

This concept is very interesting, and you perhaps ask a physicist if it is right to think of light, and of the primary particles and indeed, of all matter as complicated wavelike motions. He agrees that it is "Then," you may rely, "it only remains to know something of the medium that carries all these wavelike motions. I can see that this medium must pervade all space through which light can pass and must be the foundation of all matter. Do you know any more about it?" You may expect him to say regretfully that he does not. Or the incredible fellow may even have some more suggestions His reply is disconcerting. He says he cannot concur in the idea of such a medium. You protest He is able to explain his position, for like the flat-Earth advocate he always has very good reasons. If a person were to travel at 18 miles a second in the same direction as a beam of light, its velocity ought, of course, to appear to be less by that amount. He has tried this, and there is no change in velocity, so the idea of waves in a medium must be wrong. He attempts to soften the blow by saying that the waves he is thinking of are evidently quite hypothetical, for he finds he must measure their amplitudes not with ordinary numbers but with "complex" numbers that involve that curious idea, the square root of minus one. You ask him if he seriously suggests that light, matter, living things, people are really hypothetical waves in a medium that does not exist. If he is not cautious he says "yes." Is not this an absurb situation? This physicist is inviting you to consider yourself a mathematical fiction. Do not believe him. If anyone has felt disturbed by having collided with the theories of physics in some such way as this, my recommendation is that he make a firm return to reality by engaging in music, singing, dancing, the visual arts and the plastic arts. These deal with real things.

Indeed the physicist's answer seems so absurb one could think he was jesting. Or perhaps the original question was not well put; doubtful questions invite dusty answers. Let us pass on to the next:

What Is It That A Physicist Aims To Do?

To answer this we must consider how a physicist works. Suppose that he is faced by some new "animal." It may be a living thing or it may be some inanimate system such as a thunderstorm. He first watches what it does. He compares it in his mind with other things he has met. He adopts those useful inventions the integers and makes numerical comparisons. After a while he may venture some theories, predicting what it will do next, perhaps, or guessing what it may look like from the other side, or from the inside. Certain studies, notably astronomy, restrict one to this approach. But every physicist tries to advance to the next stage of enquiry. This is when he, so to speak, points a finger and gently pokes the animal. It reacts, and by repeating the poking in a number of ways he rapidly extends his knowledge. This is called the "controlled experiment," for he can control just how he pokes it or when or where. I would like to illustrate this by something told to me by Mr Benseman of the Physics and Engineering Laboratory. He was directing his attention to geysers in the New Zealand thermal area. Most people study geysers by watching them, but Mr Benseman wished to poke his animal. The geyser was erupting at regular intervals through a hole in a shallow pool of water at the foot of a sloping bank of ground. One might, of course, plug the hole of the geyser, and what would it do then? But rather than risk destroying this scenic attraction he dealt with it more ingeniously. He argued that the water in the pool must in some degree impede the eruptions, so what could be simpler than to pile sandbags round the rim of the pool. After the next eruption the water in the pool was about a foot deeper than before. The eruptions now became more feeble in the sense that less water was being delivered. The volume of overflowing water was being measured at a weir so this change in behaviour expressed itself numerically. Soon, however, the activity returned; each eruption was producing the customary volume of water. What should be done now? Between two eruptions Mr Benseman removed the sandbags so that the pool fell to its usual level. The next two eruptions were big ones. When the measurements were compared it was found that they had delivered, in addition to the usual amount, all the volume of water that had failed to be delivered at the time when the eruptions were weak. You see the implication. The increased pressure had caused water to be stored somewhere underground. This immediately invites one to propose some system of underground channels and chambers that would store water in this way.

This look at the actions of a physicist will, I hope, suggest to you, as it does to me, that a physicist is trying to find recipes for action. He describes a body by the ways in which it would affect other bodies and ultimately ourselves. Consider the statement that this wooden bench before me occupies a certain position in space. What does the statement mean? Among other things, it means that if I am advancing my finger downwards I would do well to arrest it before it penetrates the wood, for this would cause me discomfort. So I suggest that we adopt the following view:—

All the laws of physics are recipes for action.

If we adopt this view it disposes of most of our previous difficulties. We asked whether the Earth is really flat or really round. When we ask if a thing is "really there" we are asking whether the recipes for action that we deduce from the statement "it is there" will in all conceivable circumstances be correct. But the real world does not "is"; it acts. We are concerned with events; events are the real world. We develop concepts of position in space and a flow of time but these are only maps to help us guide ourselves among the events. If the maps provided by Newton and by the advocate of the flat Earth are equally successful in guiding us (as they might well be) then both are right.

But the advocate of the flat Earth has, so to speak, taken Newton's map, stretched it like an India rubber skin, and tied it in knots, with the result that it is more difficult to read. So we prefer Newton's map. If the modern physicist chooses to picture hypothetical waves in empty space this need not discompose us. Events are real. His curious picture is only a map.

Occam's rule becomes commonsense; one adopts the theory whose recipes are most simple to work out. Yet some may say that a difficulty remains. How does the world come to be such a place that it is possible to find simple theories or indeed any theories at all? Why are not events quite unrelated? The only explanation I have ever been offered is that God is one and not many. Some people do have a strong conviction that the world is orderly. Look at Kepler struggling for fifteen years with the numbers so rigorously collected by his master Tycho Brahe. Kepler did not know what he was looking for; he only felt he would recognise it when he saw it. One good theory leads in a very striking way to another and Newton follows Kepler, It can seem very surprising that de Broglie could declare that electrons were waves before the matter was tested, or that Yukawa could use the new quantum theory ideas to assert the nature of a kind of primary particle, the meson, that no one had ever thought of; yet these were found when they were looked for. A physicist does not have the emotional energy to go about in perpetual astonishment at the orderliness of the world. Some physicist may say that there is no point in being astonished at so obvious fact, yet I imagine that, if one of these sudden theoretical clarifications took place in him, the emotions he might record would have that flavour.

Continued on next page

page 8

Attitude Of A Physicist

Continued from page 7.

I will mention here two attitudes that are important. I think, in the practice of physics and, presumably, in the teaching of it. The first is:—

Every law in physics has been invented by a man.

One hopes that, if one can take students to the situation in which that man found himself, they will declare that he was a sensible fellow and that they would have wished to invent the same theory. Later they may be able to say, "I know why he wrote the theory as he did, but had he been aware of the results of my recent experiments he would have written it differently." And they proceed to write it differently. The second is:—

Always idealise.

A theoretical physicist never attempts to deal with the entire complexities of the world. He makes up a fictitous world in which, for example, all solids may be perfectly rigid, all fluids quite frictionless, and so on. This is called "idealising" the situation. It gives him a problem with which his logic can cope. A physical oceanographer may contemplate the sea. There are many different ways of idealising that. But you see what he is searching for. He needs an idealisation of the sea about which he can ask himself questions and which is sufficiently simple for him to answer the questions, yet the answers must be unexpected and new. When he has seen through all this and has found an intriguing answer, he turns himself into an experimentalist and goes about to find whether the sea actually behaves in this way. This mixing of fantasy and fact is the art, or artfulness, of a physicist.

Where Are The Activities Of Scientists Leading Us?

Archimedes was a notable engineer. He had satisfied himself of the properties of levels and he dramatised this by the fantastic remark that if he were given a fixed pivot he could move the Earth. Newton gave a "thought-experiment" of this type when he illustrated his ideas of the motion of the Moon. He said that, if a man were to climb a very high mountain on the globe and to set up there a cannon, the ball fired horizontally from it would begin to move on an elliptic path with the Earth's centre as a focus. If the ball could be ejected with sufficiently great speed, its orbit would never touch the Earth until it returned and struck the cannon from the rear. Fantastic, of course, but seven years ago this was done, and since then a man has ridden in one of these chariots nineteen times round the Earth and returned safely, as you very well know. He did not make each circuit in forty minutes as Shakespeare has it. He took ninety minutes, because ninety minutes is the easiest time to do it in. It could be done in forty minutes if one had propellant in the vehicle to keep it near the Earth. So I suggest:—

Technology is making actual the imaginings of poets.

Shakespeare was a poet; anyone is entitled to imaginings, of course, but poets are reputed to have more lively imaginations, so I say "poets."

The traditional poetic image of a scientist is, perhaps, Dr Faustus. Marlowe shows him as seeking accurate knowledge that will settle, in his own mind at least, the endless disputations that have seemed to him mere talk. He also wants recipes for action; any action. He also acts. This knowledge does not come to him without effort. He has to work for it.

O, what a world of profit and delight,
Of power, of honour, of omnipotence,
Is promis'd to the studious artisan!

Yet I am unable to make this image coincide in my mind with the image I have of physicists, still less with those of biologists or astronomers. Intending no offence in the world I prefer to regard Faustus as an engineer. My time in government employ has led me to see a difference. A physicist may make experiments, but the end he usually has in view is the appearance of a published paper. An engineer, on the other hand, is well aware of the difference between the idea of a machine and the machine itself. Indeed he is not well satisfied till he has seen the machine in production and widely put to use. This tendency of physicists to stop halfway has led, it seems to me, to an amused tolerance of their odd pronouncements. It is not very long ago that physicists got the idea of anti-matter. It seems that all the primary particles of matter, and we now list fifteen of them, have "anti-particles" corresponding to them, and among themselves these anti-particles would combine and react almost like the matter we know. But if ever a particle meets its anti-particle the two annul each other and nothing is left but a flash of light. Yet conceivably there might be whole galaxies of anti-matter. The news that particles of anti-matter had been observed in a laboratory won a comic verse in Punch. I can remember a little of it.

Thoughts On Anti-Matter

In Berkeley, Cal., a don
Is making anti-matter;
No sooner made than gone,
So quick its fragments scatter.
But, reader, do not sniff
Or ask him why he bothers. Is
His work not worth it if
It raises this hypothesis;
That where man's farthest sight
The deeps of space traverses,
Conceivably there might
Be anti-universes?
This theory is appealing
To most of us no doubt,
Because we have a feeling
That things should cancel out—
Beyond the last abyss
That telescopes can scan, it
Is possible there is
A pleasant anti-planet.
Where, amid learned chatter
There works an anti-don
Who's busy making matter
No sooner made than gone.

—Peter Dickinson, May 21. 1958.

(Reprinted by permission of Punch).

But in contrast to this, the idea that this Earth was being visited by little green men in flying saucers attracted widespread attention. One can understand this. It is people that matter to people. The core of the comic verse about anti-matter is the notion of the anti-don. I have worked for some years on the topic of ocean waves, yet I sometimes feel that whatever those waves may choose to do among themselves is not of the slightest interest to me. They can do what they like so long as they do not affect me or those with whom I sympathise. My interest is in what other people may think about waves or their opinions of my notions. The saying of Solomon. "It is the glory of the Lord to conceal a matter. It is the honour of the king to find it out"; this derives its entire force from the two personalities that are involved. Yet we must remember that theories of physics are recipes for action, and the same may be said, I think, of all studies. To guess where science is leading us. I will ask what kinds of enquiries it is that scientists allow themselves to pursue.

Many scientists are engaged in applied research. This means that they are focusing on some problem of technique that has economic value and are trying all ways to achieve that end. Other scientists engage in basic research. Sometimes it is called "undirected research." but this gives a wrong impression; one does not usually hit anything without aiming at it. In basic research the worker directs himself and is free to pay attention to any field of enquiry. It can be argued that people prefer basic research because it is easier. Suppose a man sets an aim for himself, that in the coming year he will find, say, three new theoretical ideas or experimental facts. Is he then not more likely to find them when he is free to let his attention rest anywhere within subjects with which he is acquainted? Yet in saying that it is more efficient. One finds more new recipes for action per man-month of effort. It is true that these recipes may not have immediate application but experience has shown that it will not be long before they are found useful, perhaps twenty years, perhaps ten, perhaps five.

This indicates the limits that scientists set themselves in their enquiries. There are none. You would find it difficult to light on any topic that someone somewhere is not zealously pursuing. The reason for this is that every scientists is on the watch for such a topic, so that may, as it were, skim off the cream before anyone else gets a chance. But if theories are recipes for action and our field of enquiry has no bounds, I think it fair to say: —

The aim of scientific enquiry is to allow us to make happen whatever we wish to happen.

It seems, after all, that we have the same aim as Faustus.

The sciences are progressing. We have not yet, of course, caught up with Faustus. We have not yet seen Helen or heard Homer sing. I suggest that it is an error to suppose that the tricks we may learn in the future will all be like the ones we know already. You cannot count on that. Perhaps we shall see some revolution in psychology. But however this may be, I invite you to imagine a community in which all your wishes can be granted; for we seem to be moving that way.

Perhaps there are dangers in such a situation. I will end by considering three of them. First there is the danger that a great increase in technical power may mean that some people will have increased power over the actions of others. This is usually thought to be bad for both parties. The Roman Emperors from Tiberius to Nero are not regarded as models of a well-ordered life. I hope therefore that political studies will show us how to combine technical power with individual freedom.

Another danger is that we may wish for things that are bad for us. There must have been many Romans who envied the power of Caesar, yet we have argued that this power had a bad effect on Caesar. The wishes that we can exercise today usually have some self regulating mechanism. A New Zealander used to having enough to eat does not, when attending a banquet, eat himself sick. Or look a little further forward to a time when the geologists and geophysicists have done their task, and you may have an earthquake or not have an earthquake, just as you wish. People will find no difficulty in deciding. Or those who want an earthquake will fly to the region where the earthquake is programmed and will enjoy their earthquake, while those who do not want it will stay at home. But we are not widely experienced in exercising wishes, and though I am not well able to make specific suggestions I imagine that some types of wish may be bad for the human psyche if they are exercised. You see the difficulty. The physical sciences may show us how to make our wishes come true but they offer little suggestion about what wishes may be advisable and what wishes may not. Fortunately there are other studies than the physical sciences. I point to Theology, Philosophy, History, Law, Anthropology, Education, Languages, Literature, Music and the Fine Arts; in short, the Humanities. We must look to these for advice and enquire their recipes for action. These studies are necessary today, as I think those engaged in them will concede; all I am suggesting is that as our technical power increases the questions that will be asked of these studies will tend to become more curious, more detailed and more urgent than questions asked of them today.

And last, what shall we do if we run out of wishes? One does not thrive without wishes. As a curious example of the demand for wishes I will say that in 1957, when the Russians were putting artificial moons in the sky, people in the United States of America wanted to do that too, of course, but they began to look for some other wish, a big one but with a different flavour. Some lively young men sitting drinking coffee in Califronia hit on it, or so I understand from one of them. "Anchor a ship in the deep ocean, lower a drill four miles to the bottom and drill a hole through the bottom of the sea." It was not, of course, intended to let the water run out. They suggested the deep sea because geophysicists know that the crust of the Earth is thinner there. Drilling another four or five miles through the ocean bed should bring the drill to that very interesting region about which there has been so much discussion, below the Mohorovichic discontinuity. One could take out a small piece from the Earth's mantle and have a look at it. This idea met with approval and the work was begun. Curiously enough, it was not long before the Russians had begun a similar venture.

We have wish-makers today. Some of them are called inventors and some are called advertising agents. We have good reason to be grateful for many of the wishes they have conceived and made real for us; anaesthetics, vaccines, motor cars and washing machines occur to me. If we have any quarrel with the advertising agent and with some of his proposals for gracious living it is because we may feel that the wishes he offers for sale are not so excellent as he makes out. One must remember that he is hampered by our primitive technology. In the community that I am inviting you to consider, it seems to me likely that wish-makers will be in great demand. They will be very highly regarded for it is they who will be called upon to offer a picture of each next adventure. It is clear that they will need most fertile imaginations. They will need most wise imaginations, too, for they will be devising wishes that are to be made real. They will indeed be the intellectual leaders of the community. They will be able with justice to quote Arthur O'Shaughnessy and say.

We are the music-makers,
And we are the dreamers of dreams,"
for that is what they will be.

And an intelligent and discriminating public will keep them up to scratch and require that their production be good and adequate At least I hope so.