Centennial of Einstein’s General Theory of Relativity: 2015

 

by

 

Damien F. Mackey

 

 

 

 

“To­wards the end of 1915, Ein­stein pro­duced his mas­ter­piece: the gen­eral the­ory of rel­a­tiv­ity.

This year, physi­cists are cel­e­brat­ing the cen­ten­nial of Ein­stein’s the­ory. They are look­ing back on the the­ory’s ori­gins, its grow­ing pains, how it is hold­ing up. And they are de­vis­ing ex­per­i­ments to test the the­ory un­der ever more ex­otic con­di­tions, to see if, or where, it may fal­ter. And most of all they are look­ing ahead, pon­der­ing the next the­ory – one that can reach even fur­ther than Ein­stein’s, by in­cor­po­rat­ing the other great idea of 20th cen­tury physics: quan­tum me­chan­ics”.

 

Dan Falk

Cosmos, Issue 65 (Oct-Nov 2015), p. 52

 

Introduction

 

Recently I tuned in to watch an SBS TV documentary with the title “Inside Einstein’s Mind”, and I was intrigued to learn that Einstein had managed, with his theory of General Relativity, to unlock the laws of nature.

This documentary is being promoted in the following laudatory terms:

 

In November 1915, Einstein published his greatest work: General Relativity, the theory that transformed our understanding of nature's laws and the entire history of the cosmos. This documentary tells the story of Einstein's masterpiece, from the simple but powerful ideas at the heart of relativity, to the revolution in cosmology still playing out in today's labs, revealing Einstein's brilliance as never before. (From the US) (Documentary) G CC

 

One had to marvel at Albert Einstein’s mathematical skill, his ability to think outside the square and to embark upon a new course, his powers of concentration, and his tenacity.

Dan Falk muses about the intense effort that Einstein must have put in:

 

A cen­tury ago Ein­stein sweated blood to give us his mind-bending the­ory of grav­ity. As tech­nol­ogy caught up, his pre­dic­tions were ver­i­fied, one by one. Now only grav­i­ta­tional waves re­main.

 

BEETHOVEN SPENT MORE THAN 16 hours a day at his pi­ano, some­times com­pos­ing four mu­si­cal works at once. Im­mersed in his task, he would be­come fever­ish, of­ten dous­ing him­self with wa­ter that soaked through the floor into the apart­ment be­low.

 

If we could time-travel to Ber­lin be­tween 1905 and 1915, we would likely find Al­bert Ein­stein at the height of his pow­ers, in a sim­i­larly febrile state. Yet he pushed on with his equa­tions know­ing, as he hinted in the let­ter to his cousin, that “great things” were within his reach.

 

But did Albert Einstein really succeed in coming to grips with the laws of nature and the origins and history of the cosmos?

Is the warp and woof of Einstein’s universe, with its lumpiness and bumpiness, really the way that the universe is, or the way of Einstein’s own imagination?

Can God be defined by an elaborate physico-mathematical equation?

 

Gavin Ardley well summed up the nature of the new theoretical physics in his classic book, Aquinas and Kant: the foundations of the modern sciences (1950).

I take here a part of his:

 

Chapter IV

THE SIGNIFICANCE OF PROCRUSTEAN SCIENCE

 

 

The ‘Otherness’ of Modern Physics

 

Post-Galilean physical science is cut off from the rest of the world and is the creation of man himself. Consequently the science, in itself, has no immediate metaphysical foundations, and no metaphysical implications, in spite of popular beliefs to the contrary. These beliefs arise from the failure to realise the science’s ‘otherness’, that it belongs to the categorial order and not to the real order.

Only that which belongs to the real order is directly linked with metaphysics. The ancient and medieval science of physics belongs to this real order, and is, in principle, an integral part of philosophy in general. It has metaphysical foundations and metaphysical implications. [Footnote: This is not to say that all the particular Aristotelean doctrines of the Earth, the Skies, the Heavens and so on, are essential to Aristotelean metaphysics. They are integrated with metaphysics only in their general intention, and not in particular formulation. They could be modified without necessitating any change in metaphysical principles since the principles of metaphysics are founded on more general grounds. Many of the particular Aristotelean opinions about phenomena were abandoned in the 17^th century with the increasingly detailed knowledge of Nature. Galileo’s Dialogues on the Two Great Systems of the World is a classic account of this revision of detailed theories of phenomena. Galileo himself, unlike many of his more extravagant followers, generally pursued this revision with considerable moderation. (See Ch. XVII). He is careful to distinguish what is true an abiding in Aristotle from what is erroneous and non-essential.]

But the ‘new science’ shifted across by degrees into the categorial order and consequently severed its immediate link with metaphysics. Few people were aware of this, [Footnote: See Ch. XVII on the enlightened views of such men as Cardinal Bellarmine in the very early days of the movement. Unfortunately, Bellarmine’s wise observations were forgotten in later years. See, too, Ch. VI on Immanuel Kant, who held the clue in the hollow of his hand, but by excess destroyed it.] least of all the physicists themselves. The general run of physicists and philosophers have gone on writing learned works on the metaphysical foundations, and more particularly the metaphysical implications, of modern physics, oblivious to this change of character. If the theory of the nature of modern physics put forward in this book is correct, then both these enquiries are vain.

Works on the supposed metaphysical foundations of modern physics may have some value however, even if not in the sense intended by the authors. For, although logically the supposed foundations are not there, yet psychologically the metaphysical background may well have prompted the physicist to introduce this or that Procrustean bed. It is one of the sources of inspiration. [Footnote: See Ch. XI on Scientific Method.] Such enquiries then are of great interest to the historian of science as indicating one possible factor which led physicists to do what they in fact did. But they do not in any way provide a metaphysical foundation for the science, since a categorial science has no such foundation, dwelling apart, as it does from the real world. [Footnote: Such a work is the valuable study of Burtt: The Metaphysical Foundaions of Modern Science (London, 1925). We might say that the significance of this work is not logical, as Burtt apparently intended, but psychological and historical. It is significant that Burtt practically ignores Kant and his Copernican revolution, which is of vital importance in this matter and leads to quite different conclusions from Burtt’s (see Ch. VI).

Reference should be made to E. W. Strong: Procedures and Metaphysics (Univ. of California Press, 1936) for an examination of the origin of modern physics from the non-metaphysical point of view advocated in this work. Strong writes (pp. 10-11):

 

The operational autonomy of science and the irrelevance of the metaphysical tradition was a conclusion arising from, rather than being a premise leading to, the present study. The theory with which the inquiry began was not confirmed by the evidence, for let it be confessed at the outset that the original intention was to consolidate the claim that the Platonic tradition was the metaphysical godfather of modern scientific thought. The study of the scientific work and opinion of the early-modern period conjoined with a correlated study of the mathematical aspect of the Platonic tradition revealed that the original theory was untenable. The problems of mathematicians and physical investigators were found to be methodological rather than proceeding from, or based on, metaphysical concepts. The meaning of concepts employed by mathematicians and scientists in their work was found to be established in the limited operations and subject matter constituting their science. The conclusion finally driven home was the conviction that the achievements of Galileo and his predecessors were in spite of rather than because of prior and contemporary metaphysical theories of mathematics.

 

This contention that there are two lines of activity, one of autonomous procedures, and the other of metaphysics, is diametrically opposed to Burtt’s thesis of homogeneity. Strong goes on to develop it with a wealth of historical evidence. Strong’s conclusions from his examination of the origins of modern mathematical-physical science in the 16th and 17^th centuries lend powerful support to our basic contention that there are two orders: an autonomous order of physico-mathematical science, and a real order which is the province of metaphysics. The contention as advanced here is founded on an examination of the nature of physical science as we have it today. Strong’s historical examination of origins is complementary to, and confirmatory of, the present work.]

While discussions of the metaphysical foundations of modern physics are comparatively rare, discussions of its supposed implications are extremely popular. In fact the implications of science are the happy hunting grounds of generations of philosophers, and physicists turned amateur philosophers.

Anxious theologians scan the latest scientific theories to see if they do or do not support the existence of God. Grave scientists issue their pontifical pronouncements. Sir James Jeans tells us that God is a great mathematician; Einstein says ‘God is slick but not mean’; Laplace, answering Napoleon who taxed him with not mentioning God in his Mécanique Céleste, said: ‘I have no need of that hypothesis’.

Puzzled philosophers delve into the intricacies of the Heisenberg uncertainty principle to determine if man does or does not possess free will, or to see if the law of causality remains valid, or if it has to be replaced by statistical probability.

[Footnote: As representative of a multitude of contemporary philosophers, let us quote one of the most acute, John Wisdom:

 

In general philosophers concern themselves with paradoxes arising from facts that come under their observation. It is important that they should be alive to the paradoxes arising from quantum facts. Such facts cannot be shelved as merely technical or as belonging to a special department; they are facts along with all the other more familiar facts about nature they are no less real because revealed by complicated laboratory apparatus than are those revealed by the human eye. (Mind, Jan. 1947, p. 81)

 

These remarks of Wisdom’s are largely vitiated by the author’s failure to take into account the Procrustean character of physics. He is tacitly assuming a realist theory or a passive phenomenalism (Ch. XVIII). ….

As an amusingly ironic account of the extravagances into which popular opinion is led by hypostatising the world of physics, let us quote from Aldous Huxley’s Time Must Have a Stop (London, 1945), Ch. 8.

 

‘As I was saying, Mr Barnack, everyone ought to know something of Einstein’.

‘Even those who can’t understand what he’s talking about?’

‘But they can, the other protested. ‘It’s only the mathematical techniques that are difficult. The principle is simple – and after all, it’s the understanding of the principle that affects values and conduct’.

Eustace laughed aloud.

‘I can just see my mother-in-law changing her values and conduct to fit the principle of relativity!’

‘Well of course she is rather elderly’, the other admitted. ‘I was thinking more of people who are young enough to be flexible. For example, that lady who acts as Mrs Gamble’s companion …’

‘… Mathematically speaking, almost illiterate’, the young man was saying. ‘But that doesn’t prevent her from realizing the scope and significance of the Einsteinian revolution’.

‘And what a revolution’, he went on with mounting enthusiasm. ‘Incomparably more important than anything that had happened in Russia or Italy. For this was the revolution that had changed the whole course of scientific thinking, brought back idealism, integrated mind into the fabric of Nature, put an end for ever to the Victorians’ nightmare universe of infinitesimal billiard balls’.

‘Too bad’, said Eustace in parenthesis. ‘I really loved those little billiard balls’.]

 

“Difficulties of a common sense and philosophical nature are frequently encountered in the acceptance of fundamentally new principles of physics, as e.g. on the introduction of relativity and quantum theories. These difficulties should not be experienced henceforth when it is realised that, in spite of misleading terms, the physical principles are not about the real world which we know so well. The physicist should become more conscious of the power he possesses to mould his subject when he is fully aware of his autonomy”.

 

Gavin Ardley,

Aquinas and Kant

 

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It is clearly the physicist who is imposing the conservation laws and making Nature fit, and not vice versa as the older logicians thought.

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Thus Gavin Ardley describes the essentially artificial nature of the modern theoretical physics (Aquinas and Kant: the foundations of the modern sciences, 1950).

The above quote is to be found in his:

 

Chapter III

THE NATURE OF MODERN PHYSICS

 

Procrustes at Work

 

As far as practice is concerned it would hardly be an exaggeration to say that the physicist holds on to a law of physics until he gets tired of it. To him it is a tool which he can use when he pleases, and discard when he pleases. Having discarded one theory he can pick up another, or perhaps even use the two at once, as has happened on more than one occasion. His choice is determined by his own habits and convenience. As a rule no single experiment can establish a law of physics on any firm basis, i.e. provide a compelling reason for the physicist to recognise it. Similarly no singe experiment can ever demolish a theory, i.e. compel the physicist to relinquish it there and then. This, of course, is quite at variance with the classical theory of the science.

Let us take a typical example and see to which pattern it conforms. The corpuscular theory of light in the hands of Newton was a fairly satisfactory theory of the nature of light. But with increasing interest in the phenomena of optical interference it became more and more difficult and troublesome to hold the corpuscular theory, while the wave theory became more and more attractive. No single experiment could finally demolish the corpuscular theory. It was only necessary to introduce more and more auxiliary hypotheses and the corpuscular theory, and its interpretation of the phenomena, could have been retained indefinitely. But in time most physicists came to feel that it was not worth while, that it had become too cumbersome. They grew tired of the corpuscular theory, and early in the 19th century they turned to what had by then become the much simpler wave theory, and thenceforth interpreted the phenomena in terms of the latter.

However, at the end of the 19^th century and the beginning of the 20^th century, with new discoveries, a greatly modified corpuscular theory was revived under the name of the quantum theory. The quantum theory and the wave theory were employed conjointly for a number of years until finally both were subsumed in the theory of ‘wave mechanics’.

Throughout the history of the theories of light there is very little of the ‘observing uniformities and generalising them into laws’, and very much of the physicist as the master operating successive Procrustean beds.

A particularly striking case of the a priori nature of physical theories and laws is provided by the particle known as the neutrino. In the beta-particle decay of radio-active nuclei, a continuous spectrum of beta-rays is emitted. This continuous spectrum provides one of the major problems of contemporary physics. A consideration of the process shows that either the classical laws of the conservation of energy and angular momentum are not obeyed by individual nuclei, or else another particle, hitherto unknown, which Fermi called the ‘neutrino’, is emitted along with the electron. This new particle is given just the spin and energy needed to make up the discrepancies, but it will have no charge and practically no mass. Consequently its detection would be difficult by any direct means. Nevertheless most physicists follow Fermi in postulating the neutrino, simply because it saves the conservation laws. It is quite ad hoc, but it prevents the laws being violated. The physicist’s Procrustean rôle is quite apparent. It is clearly the physicist who is imposing the conservation laws and making Nature fit, and not vice versa as the older logicians thought.

It is the same throughout physics: the physicist is the law-giver. He makes and imposes the laws, and has power to enforce them or withdraw them as he sees fit.

Again, reverting to the early days of modern physics, we may ask: how did Galileo know that in the absence of resistance to motion all bodies would fall towards the Earth with the same acceleration? How did Newton know his laws of motion to be true; in particular, that every body continues in its state of rest or of uniform motion in a straight line unless compelled by external force to change that state? Did Galileo and Newton discover these law or invent them? Are they ‘natural’ or Procrustean? When we consider the mater we are driven to put them in the latter category.

Galileo can hold to his contention as long as he pleases by attributing departures from equal acceleration to resistances to motion. But how do we know there is resistance to motion? By reduced acceleration! Similarly Newton preserves his first law by attributing any departure from uniform rectilinear motion to an impressed force. But how do we know when there is such a force? By observing a departure from uniform rectilinear motion!

On this procedure it is impossible ever to disprove the laws so long as physicists choose to retain them. [Footnote: Cf. Ch. X on the alleged non-existence of badgers.]

Try to grasp the laws intellectually, as laws of Nature, and we are in a vicious circle from which there is no escape. Regard them as Procrustean beds and their function is clear.

Let us turn now from particular theories to a wider horizon. Here we will find some illuminating situations.

 

Ardley here turns to a consideration of experiments relating to the Special Theory of Relativity:

 

One instance which must give everyone food for thought is the case of the American physicist, D. C. Miller. It is well known that one of the strongest experimental grounds for the special theory of relativity is the Michelson-Morley experiment performed in the year 1887. This celebrated experiment was designed to detect the motion of the earth through the ether. The result was negative. No relative motion could be detected. The negative result of this experiment has become fundamental to a great deal of modern physics.

But the interesting sequel is that since then Miller has made an exhaustive investigation, and has persistently achieved positive results in his repetition of the principle of the Michelson-Morley experiment. [Footnote: See Miller, D. C. : Reviews of Modern Physics, 5, 203, (1933).] However his has been a voice crying in the wilderness, for the physicists have heeded him not. Special relativity is so firmly entrenched that any fundamental change at this stage is unthinkable. In other words special relativity has hardened into a Procrustean bed to which physicists are clinging tenaciously, and in terms of which they are interpreting the world. The physicists are not inclined to give up their bed at present, Miller or no Miller. ….

 

One of the beauties of Ardley’s thesis is that it clearly demonstrates the legitimacy of metaphysics as a study quite autonomous from modern theoretical science.

The proponents of Scientism, which modern phenomenon Wikipedia well defines as (https://en.wikipedia.org/wiki/Scientism) “a belief in the universal applicability of the scientific method and approach, and the view that empirical science constitutes the most "authoritative" worldview or the most valuable part of human learning—to the exclusion of other viewpoints”, have thought themselves entitled to announce the downfall of metaphysics as an irrelevance. Ardley, still in Chapter III makes the distinction between the two disciplines:

 

The Physicist and the Philosopher

 

…. A generation ago, when ‘relativity’ was prominently before the public eye, disputes about space and time between the philosophers and the relativity physicists were well nigh interminable. But the considerations put forward here show that such disputes are baseless. The parties were all unknowingly, discussing different things. The mistaken belief that the physicists are talking about the real space, time, and matter of the metaphysicians, arises in part because the physicists still use these names, but without the literal reality.

A recent writer on electromagnetic theory, J. A. Stratton, approaches his subject in somewhat the spirit of the foregoing. Stratton commences: ‘By an electromagnetic field let us understand the domain of the four vectors E and B, D and H’. He does not attempt to draw a red herring across the trail in the traditional manner by professing to derive these entities, E, B, D and H (a domain, we might say, of mental ‘artifacts’ [Footnote: On artifacts, se Ch. XVI.]). He leaves it to the sequel to give what pragmatic reasons he can find for inducing people to take an interest in the domain of E, B, D and H. Stratton puts a completely arbitrary system before us. When we ask Why? What is it all about? What is the good of it? he will answer by pointing to its pragmatic sanctions, in so far as he may be able. And the pragmatic sanction is its power of co-ordination and prediction. The system does not profess to tell us anything immediately about the nature of the real world.

Stratton’s mode of casting physics might well serve as a model for other writers. It would banish much of the present obscurity.

If we wish to sum up modern physics in a phrase, we could call it ‘a priori pragmatism’. This is a far cry from the old classical empiricist doctrine, which professed to build up from Nature. In fact it is precisely the reverse, since it makes contact with ‘Nature’ not at the beginning, but at the end. [Footnote: It is here that the deductive system of modern physics and the deductive system of Plato in the central Book of the Republic differ so fundamentally, in spite of a superficial resemblance. For with Plato the first principle, the Form of the Good, is grasped intellectually and intuitively. Consequently the whole hierarchical system is supremely grounded on Nature at the beginning. There is nothing of this in the hierarchical system of modern physics, where the sanction is always at the extremities not at the apex.]

Let us carry on Stratton’s principles, and say: ‘the world of modern physics is the domain of the artifacts m, s, t, F, E, B, D, H, etc., etc’. This leaves open the question of the relation of this world of artifacts to the real world. This is for the philosopher to determine, not the physicist. ….

 

Dan Falk, writing for Cosmos, continues here:

 

But for now, Ein­stein’s the­ory reigns supreme. “There’s not a sin­gle experiment that has gone against it – at least, not one that’s ever been con­firmed,” says Clifford Will, a physi­cist and gen­eral rel­a­tiv­ity ex­pert at the Univer­sity of Florida in Gainesville. “It’s passed ev­ery test with fly­ing colours”.

 

However, before we become over-excited about Einstein’s amazing strike rate as according to Falk and Will, recall what was previously observed about the rôle of the modern physicist:

 

…. The physicist’s Procrustean rôle is quite apparent. It is clearly the physicist who is imposing the conservation laws and making Nature fit, and not vice versa as the older logicians thought.

It is the same throughout physics: the physicist is the law-giver. He makes and imposes the laws, and has power to enforce them or withdraw them as he sees fit.

Again, reverting to the early days of modern physics, we may ask: how did Galileo know that in the absence of resistance to motion all bodies would fall towards the Earth with the same acceleration? How did Newton know his laws of motion to be true; in particular, that every body continues in its state of rest or of uniform motion in a straight line unless compelled by external force to change that state? Did Galileo and Newton discover these law or invent them? Are they ‘natural’ or Procrustean? When we consider the mater we are driven to put them in the latter category.

Galileo can hold to his contention as long as he pleases by attributing departures from equal acceleration to resistances to motion. But how do we know there is resistance to motion? By reduced acceleration! Similarly Newton preserves his first law by attributing any departure from uniform rectilinear motion to an impressed force. But how do we know when there is such a force? By observing a departure from uniform rectilinear motion!

 

The same sorts of questions may be asked of Einstein’s General Theory of Relativity and why experimentation has universally been confirming it.

 

We now continue with Gavin Ardley’s incisive analysis of the activities of the modern physicist (Aquinas and Kant: the foundations of the modern sciences, 1950), still in his:

 

Chapter III

THE NATURE OF MODERN PHYSICS

 

Physics and Nature

 

The world of modern physics is not the natural world. It is a remote domain of artifacts more removed from the world of Nature than the worlds in which Mr Pickwick and Hamlet dwell. The world of physics is austere and exacting, but withal a world of deep and abiding beauty. It is this aesthetic quality, perhaps even more than the satisfaction of intellectual curiosity and the desire for power, which explains its hold on its exponents. The beauty of pure mathematics has been recognised at least since the days of Plato. Pure physics has this beauty too, and in addition an intangible quality peculiar to itself which is well known to those who have entered its inner temples. This, rather than the exploration of nature, must be the physicist’s apology.

But it may well be asked now: what is the relation between physics and Nature? If physics dwells apart, how does it come into contact with Nature. And furthermore, it may be asked, why is it so successful?

In a general way, the solution of the first part of this question lies in the fact that the process of systematic experiment is selective and transforming. Hence it is that the transition is made from Nature to the abstract world, and vice versa. This is the link between the two worlds.

As regards the second question – why, if physics is an abstract and arbitrary system, is it so successful? – we might ask in return, what is the standard of success? How much more or less successful physics might have been had it been developed in different ways from the way it was in fact developed, we do not know. If the net dragged through the world by the physicists had been quite different, the outcome might have been very different too. It may have been much more successful, or much less so. We have no standard of comparison for success, so the question is scarcely profitable.

In discussing success it may be helpful to compare together two different branches of physics. The classical mechanics as applied to the solar system was generally regarded as a dazzling success. But on the other end of the scale the theory of electromagnetics is regarded today by most students of the subject as being in a state of well-nigh hopeless confusion, although with experience it can be made to work moderately well. Evidently some wrong turning was made early in the development of this latter branch of physics, and with the root trouble, whatever it is, firmly entrenched, the subject appears to be growing in disorder and chaos rather than improving. Evidently it would be better to start afresh from the beginning and drag some quite different net through the world in this particular realm.

Such considerations as these should give us pause before we speak lightly of the ‘success’ of physical science.

A variant on this question Why if arbitrary then success? is to insist that if a law or theory enjoys success, then, in the same measure, it is probable that Nature is really like the situation envisaged by that law or theory. E.g. if the law of Gravitation is well established in physics, then there must really be this Gravitation in the world, and so on. In answer to this objection we cannot do better than quote the words of Wittgenstein in his Tractatus Logico-Philosophicus, where he propounds much the same doctrine concerning the laws of physics as we have in this chapter. In the course of a most penetrating discussion of the subject he remarks:

 

The fact that it can be described by Newtonian mechanics asserts nothing about the world; but this asserts something, namely, that it can be described in that particular way in which as matter of fact it is described. The fact, too, that it can be described more simply by one system of mechanics than by another says something about the world. [Tractatus, 6.342.]

 

If the laws of physics were really found in the world, then the laws would tell us something about the world. But if the laws of physics are superimposed on the world, then the laws themselves tell us nothing about the world. [Footnote: This incidentally provides the solution to the controversy which raged throughout the Middle Ages concerning the status of the various systems of astronomy. See Appendix.] Only the character of the particular description which we effect in terms of the super-imposed law has any bearing on the world. It is only in this second order manner that we make contact with the world. ….

Hence there is no foundation for the assertion that in modern physics a law or theory, if successful, tells us what Nature is like.

This is a most important conclusion.

 

The Practice of Physics

 

Apart from the possibility of a far-reaching hyper-physics being developed, these new views about physics are not likely to make much direct difference to the practice of physics. But indirectly they may have a considerable effect. The delusion that modern physics is directly concerned with Nature, with space, time, matter, and so on, has undoubtedly hampered the growth of the science considerably during the last few centuries. The physicist should now become bolder when he realises that he, not Nature, is at the helm. He should more easily be able to cast aside old ties and inhibitions. Difficulties of a common sense and philosophical nature are frequently encountered in the acceptance of fundamentally new principles of physics, as e.g. on the introduction of relativity and quantum theories. These difficulties should not be experienced henceforth when it is realised that, in spite of misleading terms, the physical principles are not about the real world which we know so well. The physicist should become more conscious of the power he possesses to mould his subject when he is fully aware of his autonomy.

However, apart from this increased freedom, practice is not going to be altered one whit. The physicist spends most of his time applying the discipline he has so laboriously acquired. For this there is little need to know much about the whys and wherefores of the discipline. The main thing is to be able to use it. It makes little difference to the practice whether the laws of physics are a priori or not. In fact we usually find that the best experimental physicists are quite poor at discussing the nature of their subject. This is an observation which applies not only to physics, but is almost as true in literature, music, and art. The poet, the musician, and the painter are often the last people to go to for an intelligible account of the foundation of their arts. The have a divine talent, they live the life. That is enough. It is for others, with aesthetic sensibilities, but of a more philosophical turn of mind, to enquire into the nature of the arts. Returning to the physicist: in his laboratory, with his white coat on so to speak, it is scarcely exaggerating to say that he has some of the attributes of a robot and some of a slave. And quite rightly so. This is his function, and if he considers physics worth while the physicist must be prepared to subject himself to his stern taskmaster. He has a task to perform, and the best physicist is he who performs it most diligently.

This applies to by far the greater part of the average physicist’s working life. But occasionally he is called upon to promulgate a new theory or law. In its formulation he needs to exercise his imagination, and theoretical physicists in particular often combine an imaginative gift of a high order with their more ordinary capacity for routine discipline. This imaginative power has come particularly to the fore in recent times. Dirac’s amazing theory of the positive electron is a good example. [Footnote: Very briefly, according to Dirac the whole universe is filled with a continuum of electrons of negative energy, i.e. of negative mass. A g-ray quantum, of energy greater than one million electron-volts, may impart its energy to one of these electrons. The electron leaves the continuum, acquires positive mass, and is observed as an ordinary negatively charged electron. At the same time the quantum disappears, and the hole left in the continuum is the positive electron.

This phenomenon of the production of positive and negative electron pairs by the annihilation of a quantum may be observed in the Wilson Cloud Chamber.

After a short lapse of time the positive electron will meet a negative electron. The negative electron will fall into the hole, which is what the positive electron consists of. In this way both electrons are annihilated and the energy re-appears as a one million-volt quantum.] With the wider spread of the Procrustean interpretation of physics, and the consequent increased emancipation of the subject, we may expect this imaginative element in physics to flower even more luxuriantly.

The whole question of the physicist’s imaginative powers, and hence of the origin of the forms of laws and theories, is one which has been all too little discussed in histories of physics. [Footnote: See Ch. XI on Scientific Method.]

 

The Rôle of Physics

 

The new orientation to the subject is significant as regards the status of physics in the world. It is likely to make a considerable difference in the rôle of physics in man’s thinking, whether he believes physics is wresting out the secrets of Nature, or whether he believes the whole thing is quite artificial, and only of utilitarian and aesthetic significance, valuable as these latter may be.

When it is generally realised that modern physics is not really telling us anything of the world about us, in other words that the ontological status of the world of physics is very low, then we might expect that physic will be allotted to its proper place as an auxiliary to life and a fascinating intellectual exercise. Then, being released from our self-imposed shackles, we will be free to turn our attention elsewhere in search of the real world. There we will find real matter, time, and space. We learn more about time from the simple words of the hymn:

Time, like an ever-rolling stream,

Bears all its sons away.

 

than from any text-book of physics.

This mental freedmen will be good for the layman, and it will be good too, for the physicist, in so far as he is a man. For the physicist is not always in his laboratory disciplining himself. Sometimes he emerges into the real world of everyday life with its warmth and colour, hopes and fears, its beauty, love, laughter, tears, its good and its evil. This is a world of values, quite different from the monotone of physics where values have been systematically excluded. In this real world the physicist finds modern physics but a broken reed. Of course, no human being is completely devoid of the knowledge of real life. The complete and utter physicist could not continue to live. The physicist – like nearly all scientists – must lead something of a dual existence. He leads one life in the laboratory and another and quite different life outside it.

Finally, we must allude to a subject which will be discussed more fully in another chapter. [Footnote: Ch. X.] With the change in the status of physics we may expect a change in the prevailing fashions in contemporary schools of philosophy. Some of the most influential of these schools are ultra-empirical and positivistic in tone. The model for their thinking is, by and large, physics. They try to map put out the world along lines appropriate to physics. For everything other than physics the result is incredible barrenness.

Now that we see physics in a different light, perhaps the philosophical craze to ape the physicist will die out, and philosophy can resume its proper rôle of comprehending the real world in so far as that is possible to us. Metaphysics has been held up to scorn and ridicule by many since the rise of modern physical science. But now we see that physics does not deal with the real world at all. This is the province of metaphysics.

To scorn metaphysics in the name of modern physics is to misunderstand the situation. Metaphysics should thus come back into its own again, once physics has been relegated to its proper place.