The Philosophical Impact of Contemporary Physics

Milic Capek

• Publisher: Barakaldo Books
• Year: 2020
• eBook ISBN: 9781839745706
• Topic: Filosofia
• Subtopic: Filosofia etica e morale

The present book has grown out of the conviction that no true understanding of contemporary physics and its philosophical implications is possible without first fully realizing in what sense and to what extent modern physical concepts differ from the concepts of classical physics. The classical concepts of space, time, matter, motion, energy, and causality have been radically transformed recently; although the words used by contemporary physicists are the same, their connotations are altogether different from those of their classical counterparts. There is hardly any similarity between the "matter" of modern physics and the traditional material substance of the classical period, and this is true in varying degrees of other concepts as well. The revolutionary character of modern concepts cannot be fully grasped as long as the contrasting background of classical physics is not kept constantly in sight. To bring into full focus an awareness of the contrast between the classical and the modern conceptual frameworks is one of the purposes of this book.

PART I—THE CLASSICAL PICTURE OF THE PHYSICAL WORLD

I THE GENERAL CHARACTER OF CLASSICAL PHYSICS

When we speak of the classical picture of physical reality, we are indicating by the very choice of the word its most significant feature: its pictorial character. This character became conspicuous only in recent times. Before 1900 it appeared so natural and obvious that hardly anybody noticed it; what appears obvious is rarely conspicuous and rarely attracts attention. Nobody talked about Euclidean geometry before Lobachevski and Riemann, during the centuries that “geometry” and “Euclidean geometry” were entirely synonymous terms. But the emergence of new conceptions of matter provided a necessary contrasting backdrop against which the classical picture appeared in a new and unfamiliar light.

The words “picture” and “conceptions” well indicate a difference between classical and modern theories: in classical theories sensory features—especially visual and tactile—played a decisive role; modern theories, by virtue of their abstruse nature, defy all attempts at consistent visualization and pictorialization. Optical and tactile qualities, which seemed to classical physicists the inherent attributes of matter, are in the light of modern discoveries hardly more than superficial aspects of the reality whose intrinsic nature lies very probably beyond the reach of our imaginative faculties. To modern theories it is impossible to apply the precept which John Tyndall recommended in his Liverpool address to the physicists of the Victorian era as a reliable criterion of satisfactory scientific theories: “Ask your imagination if it will accept it,”{7} i.e., ask yourself if you are able to draw a mental picture of the phenomenon in question; reject it if no visual diagram, no mechanical model can be constructed. This demand hardly varied from the seventeenth to the nineteenth century; Tyndall’s recommendation is basically the same as that of Descartes and Huygens. The Cartesian ideal of explanation by figures and motions [par figures et mouvements] remained the inspiring motive of Faraday, Maxwell, Hertz, and Kelvin and even, at the beginning of this century, of Lorentz and J. J. Thomson.{8} From the epistemological point of view this is probably the most significant and revealing trait of the classical theories.

In spite of its visual and, more generally, sensory character, the classical view was certainly not a simple duplication of naive sense perception. On the contrary, the whole development of classical physics led to a progressive sifting of the original sensory data. The so-called secondary qualities like color, sound, flavor, and scent were regarded as private reactions of the perceiving mind. Only the sensation of contact and that of resistance—the latter being considered as a mere intensification of the former—retained their privileged epistemological status in providing us with a direct insight into the intimate nature of matter. It was believed that the objective counterpart of the sensation of resistance was impenetrability or solidity, and this constituted the very essence of matter. All other physical properties of matter—softness, roughness, smoothness, resilience, flexibility, ductility, wetness, fluidity, and the like—were assigned, not to matter itself, but to the subjective sphere of human perception. In this view fluidity, for instance, is a mere psychical addition to matter; the physical reality itself, or at least its constitutive elements, are completely devoid of fluidity. Similarly, there is a sensation of warmth, but there is no objective occult quality of warmth residing in the nature of reality.

Thus only a small subclass of tactile sensations—the sensations of contact and resistance—possessed the special privilege of disclosing the true nature of physical reality. While the mechanical properties of matter were thus constructed of our tactile sensations, its geometrical and kinematic attributes were conceived in visual terms. The particles of matter were imagined to possess a certain bulk, shape, and position; their positions were imagined to vary in time, or, in more ordinary language, the particles were imagined to move through space.

This is what may be called the corpuscular-kinetic view of matter. Its first formulation, a surprisingly accurate one, appeared in early Greek atomism. Its basic premises have hardly changed through the ages. Although atomism suffered a temporary (by no means complete) eclipse in the Middle Ages, it reasserted itself with renewed vigor in the century of Gassendi and Newton and since then has exerted a persistent and fascinating influence on the imagination of physicists, at least until the end of the last century. Today, for reasons expounded in Part II, its attractiveness is weakened, but not altogether destroyed.

The very persistence of this influence shows that it was due not to a simple accident of history, but rather to some inherent tendency of human intellect, a tendency that will be more extensively analyzed later. Suffice it to say here that the classical view of matter, though itself a result of a profound modification of immediate sense perception, nevertheless did not challenge seriously our imaginative faculties. As it was built of the elements of two basic senses, sight and touch, it did not transcend the limits of our sensory imagination. The subordination of all other senses to sight and touch probably explains why elimination of the secondary qualities hardly required a great mental effort even at the very dawn of Western thought. On the contrary, this elimination resulted in a distinct advantage.

The world of atoms, in which all qualitative diversity is reduced to differences in configuration and motion of the homogeneous and permanent elements, stands in striking contrast to the “confused” realm of perishing and heterogeneous sensory qualities. There is no question but that the corpuscular-kinetic scheme of nature, in virtue of its greater simplicity, clarity, and manageableness, represented a true economy of thought in the sense of William of Occam and Ernst Mach; for while it eliminated what Professor Margenau calls “the haziness of the immediately given,”{9} it retained its pictorial and, more generally, intuitive (anschaulich) character. It is true that Mach himself did not recognize in atomism an application of his own epistemological principle; in this respect his attitude remained dogmatically negative in spite of increasing empirical evidence for the existence of atoms. (Curiously enough, his attitude was much less critical toward atomism in psychology, on which his associationism was based.)

The question to what extent the principle of parsimony is a reliable epistemological criterion in modern physics will be discussed later. The fact is that the general constitution of the human mind, together with the steadily increasing amount of empirical evidence at the end of the last century, strengthened the conviction that the corpuscular-kinetic scheme was an adequate and final representation of physical reality. The universe was regarded as an enormous aggregate of bits of homogeneous material whose quantity remained constant while the spatial distribution was continuously changing according to the immutable laws of mechanics. Classical concepts of space, time, matter, motion, and causality were the main constitutive parts of this pictorial scheme, and in spite of their highly abstract nature, they all were based on the same visual and tactual elements as were characteristic of the whole imaginative background of classical physics.

II THE CONCEPT OF SPACE

THE SUBSTANTIALITY AND IMMUTABILITY OF SPACE

IN CLASSICAL science space was regarded as a homogeneous medium existing objectively and independently of its physical content, whose rigid and timeless structure has been described by the axioms and theorems of Euclidean geometry. This self-sufficiency of space and its independence of the matter which it contains was clearly formulated by Newton in his Principia: “Absolute space, in its own nature, without regard to anything external, remains always similar and immovable.”{10}

This was a basic assumption of classical science. Newton was not the first who formulated it, even though it is frequently associated with his name. To say nothing of Pierre Gassendi, Henry More, and several philosophers of the Renaissance—in particular Telesio, Pattrizzi, Bruno, and Campanella{11}—Newton’s conception was virtually present in ancient atomism, as Einstein, shortly before his death, emphasized.{12} As soon as matter was defined as a plenum—that is, occupied space—in contrast to the void or empty space, the distinction was established between the immutable and independent container and its changing physical content.

We do not need to be confused by the fact that the Greek atomists of the fifth century B.C., Leucippus and Democritus, called space “Non-Being” and contrasted it with eternal and indestructible “Full Being,” παμπλήρες όν. First, the term τὀ μἠ ὅν (Non-Being) is one they accepted from the earlier Eleatic philosophers Parmenides and Melissos, for whom Non-Being was a simple nothingness. Leucippus took over the Eleatic language but not the Eleatic thought. In his view there was no solution to the paradoxes which had been so much stressed by the Eleatics unless even the void was granted a certain degree of existence—the kind of existence that belongs to empty space, the necessary condition, as it was thought, for the reality of motion and diversity. Indeed, Democritus, taking advantage of the subtle distinction between two Greek negatives, coined his own term for space—“not Being” (τὀ οὐκ ὅν); he thus avoided the original misleading term, accepted by Leucippus, which was so strongly reminiscent of the sheer Eleatic nothingness.{13}

Second, matter itself, though in its essence immutable and quantitatively constant, was in a certain sense subject to change because its constitutive parts were endowed with motion. It is true that this change did not affect the particles themselves, but only their distances apart; nevertheless in contrast to the changing configurations of matter, space possessed unchangeability in a full and absolute sense.

Thus, in the last analysis, the notion of independent Newtonian space lurks behind any explicit distinction between material stuff and the place it occupies: the underlying positions remain eternally the same, their occupants vary from time to time. In more common language, matter moves in space. It is precisely this logical separability of the empty immovable container from its movable material content which makes displacement possible. Greek atomists, in stressing this separability of space and matter, undoubtedly prepared the way for the Newtonian concept of independent and absolute space.

True immutability thus belongs to space alone. With respect to space even the eternal atoms of Democritus and of later atomists appear as accessory, contingent, and even subject to change. They appear accessory because, being defined as “full volumes of space,” they need space for their existence, while the converse is not true—space can exist without them. They appear contingent because their occupation of certain positions is only accidental in the sense that it does not possess a logical necessity comparable to the timeless geometrical relations holding between the positions themselves. Finally, they appear even changing in a certain sense—if not themselves, at least in their mutual relations in space.

This may be stated in another way. In classical atomistic science space was logically prior to its material content. It is true that classical physics and the mechanistic philosophy which grew out of it loudly proclaimed that material substance is the only true reality; it would be hardly compatible with this allegedly strict monism if the reality of any entities other than matter were equally emphasized. But whether the existence of empty space was silently assumed or whether it was explicitly asserted as, for instance, by the atomists, its logical priority to matter was not sufficiently realized. This was only natural. How could such a negative reality, called τὀ οὐκ ὅν (not Being) by Democritus, inane by Lucretius, nihil by William Gilbert and Otto von Guericke,{14} be regarded as logically antecedent to the solid reality of eternal and indestructible atoms? How could Non-Being be l...

Table of contents

• Title page
• TABLE OF CONTENTS
• PREFACE
• INTRODUCTION
• PART I-THE CLASSICAL PICTURE OF THE PHYSICAL WORLD
• PART II-THE DISINTEGRATION OF THE CLASSICAL FRAMEWORK AND THE SIGNIFICANCE OF NEW CONCEPTS