Revolution in physics
Two thousand years ago, it was thought that the laws of the universe were completely covered by Euclid's geometry. There was nothing more to be said. This is the illusion of every period. For a long time after Newton's death, scientists thought that he had said the last word about the laws of nature. Laplace lamented that there was only one universe, and that Newton had had the good fortune to discover all its laws. For two hundred years, Newton's particle theory of light was generally accepted, as against the theory, advocated by the Dutch physicist Christiaan Huygens (1629-95), that light was a wave. Then the particle theory was negated by the Frenchman, Augustin Jean Fresnel (1788-27), whose wave theory was experimentally confirmed by Jean.B.L. Foucault (1819-68). Newton had predicted that light, which travels at 186,000 miles per second (around 300,000 km) in empty space, should travel faster in water. The supporters of the wave theory predicted a lower speed, and were shown to be correct.
The great breakthrough for wave theory, however, was accomplished by the outstanding Scottish scientist James Clerk Maxwell, in the latter half of the 19th century. Maxwell based himself in the first instance on the experimental work of Michael Faraday, who discovered electromagnetic induction, and investigated the properties of the magnet, with its two poles, north and south, involving invisible forces stretching to the ends of the earth. Maxwell gave these empirical discoveries a universal form by translating them into mathematics. His work led to the discovery of the field, on which Einstein later based his general theory of relativity. One generation stands on the shoulders of its predecessors, both negating and preserving earlier discoveries, continually deepening them, and giving them a more general form and content.
Seven years after Maxwell's death, Heinrich Rudolf Hertz (1857-94) first detected the electromagnetic waves predicted by Maxwell. The particle theory, which had held sway ever since Newton, appeared to be annihilated by Maxwell's electromagnetics. Once again, scientists believed themselves in possession of a theory that could explain everything. There were just a few questions to be cleared up, and we would really know all there was to know about the workings of the universe. Of course, there were a few discrepancies that were troublesome, but they appeared to be small details which could safely be ignored. However, within a few decades, these “minor” discrepancies proved sufficient to overthrow the entire edifice and effect a veritable scientific revolution.
Waves or particles?
Everyone knows what a wave is. It is a common feature associated with water. Just as waves can be caused by a duck moving over the surface of a pond, so a charged particle, an electron for example, can cause an electromagnetic wave, when it moves through space. The oscillatory motion of the electron disturbs the electric and magnetic fields, causing waves to spread out continuously, like the ripples on the pond. Of course, the analogy is only approximate. There is a fundamental difference between a wave on water and an electromagnetic wave. The latter does not require a continuous medium through which to travel, like water. An electromagnetic oscillation is a periodical disturbance that propagates itself through the electrical structure of matter. However, the comparison may help to make the idea clearer.
The fact that we cannot see these waves does not mean that their presence cannot be detected even in everyday life. We have direct experience of light waves and radio waves, and even X-rays. The only differences between them are their frequency. We know that a wave on water will cause a floating object to bob up and down faster or slower, depending on the intensity of the wave—the ripples caused by the duck, as compared to those provoked by a speedboat. Similarly, the oscillations of the electrons will be proportionate to the intensity of the light wave.
The equations of Maxwell, backed up by the experiments of Hertz and others, provided powerful evidence to support the theory that light consisted of waves, which were electromagnetic in character. However, at the turn of the century, evidence was accumulating which suggested that this theory was wrong. In 1900 Max Planck had shown that the classical wave theory made predictions that were not verified in practice. He suggested that light came in discrete particles or “packets” ( quanta). The situation was complicated by the fact that different experiments proved different things. It could be shown that an electron was a particle by letting it strike a fluorescent screen and observing the resulting scintillations; or by watching the tracks made by electrons in a cloud chamber; or by the tiny spot that appeared on a developed photographer's plate. On the other hand, if two holes are made in a screen, and electrons were allowed to flood in from a single source, they caused an interference pattern, which indicated the presence of a wave.
The most peculiar result of all, however, was obtained in the celebrated two-slot experiment, in which a single electron is fired at a screen containing two slots and a photographer's plate behind it. Which of the two holes did the electron pass through? The interference pattern on the plate is quite clearly a two-hole pattern. This proves that the electron must have gone through both holes, and then set up an interference pattern. This is against all the laws of common sense, but it has been shown to be irrefutable. The electron behaves both like a particle and a wave. It is in two (or more than two) places at once, and in several states of motion at once! However, as Banesh Hoffmann comments:
“Let us not imagine that scientists accepted these new ideas with cries of joy. They fought them and resisted them as much as they could, inventing all sorts of traps and alternative hypotheses in vain attempts to escape them. But the glaring paradoxes were there as early as 1905 in the case of light, and even earlier, and no one had the courage or wit to resolve them until the advent of the new quantum mechanics. The new ideas are so difficult to accept because we still instinctively strive to picture them in terms of the old-fashioned particle, despite Heisenberg's indeterminacy principle. We still shrink from visualising an electron as something which, having motion, may have no position, and having position, may have no such thing as motion or rest.” 1
Here we see the negation of the negation at work. At first sight, we seem to have come full circle. Newton's particle theory of light was negated by Maxwell's wave theory. This, in turn, was negated by the new particle theory, advocated by Planck and Einstein. Yet this does not mean going back to the old Newtonian theory, but a qualitative leap forward, involving a genuine revolution in science. All of science had to be overhauled, including Newton's law of gravitation.
This revolution did not invalidate Maxwell's equations, which still remain valid for a vast field of operations. It merely showed that, beyond certain limits, the ideas of classical physics no longer apply. The phenomena of the world of subatomic particles cannot be understood by the methods of classical mechanics. Here the ideas of quantum mechanics and relativity come into play. For most of the present century, physics has been dominated by the theory of relativity and quantum mechanics that in the beginning were rejected out of hand by the scientific establishment, which clung tenaciously to the old views. There is an important lesson here. Any attempt to impose a “final solution” to our view of the universe is doomed to fail.
The development of quantum physics represented a giant step forward in science, a decisive break with the old stultifying mechanical determinism of “classical” physics. (The “metaphysical” method, as Engels would have called it.) Instead, we have a much more flexible, dynamic—in a word dialectical—view of nature. Beginning with Planck's discovery of the existence of the quantum, which at first appeared to be a tiny detail, almost an anecdote, the face of physics was transformed. Here was a new science which could explain the phenomenon of radioactive transformation and analyse in great detail the complex data of spectroscopy. It directly led to the establishment of a new science—theoretical chemistry, capable of solving previously insoluble questions. In general, a whole series of theoretical difficulties were eliminated, once the new standpoint was accepted. The new physics revealed the staggering forces locked up within the atomic nucleus. This led directly to the exploitation of nuclear energy—the path to the potential destruction of life on earth—or the vista of undreamed of and limitless abundance and social progress through the peaceful use of nuclear fusion. Einstein's theory of relativity explains that mass and energy are equivalents. If the mass of an object is known, by multiplying it by the square of the speed of light, it becomes energy.
Einstein (1879-1955) showed that light, hitherto thought of as a wave, behaved like a particle. Light, in other words, is just another form of matter. This was proved in 1919, when it was shown that light bends under the force of gravity. Louis de Broglie later pointed out that matter, which was thought to consist of particles, partakes of the nature of waves. The division between matter and energy was abolished once and for all. Matter and energy are…the same. Here was a mighty advance for science. And from the standpoint of dialectical materialism matter and energy are the same. Engels described energy (“motion”) as “the mode of existence, the inherent attribute, of matter.” 2
The argument that dominated particle physics for many years, whether subatomic particles like photons and electrons were particles or waves was finally resolved by quantum mechanics, which asserts that subatomic particles can and do behave both like a particle and like a wave. Like a wave, light produces interferences, yet a photon of light also bounces off all electrons, like a particle. This goes against the laws of formal logic. How can “common sense” accept that an electron can be in two places at the same time? Or even move, at incredible speeds, simultaneously, in different directions? For light to behave both as a wave and as a particle was seen as an intolerable contradiction. The attempts to explain the contradictory phenomena of the subatomic world in terms of formal logic leads to the abandonment of rational thinking all together. In his conclusion to a work dealing with the quantum revolution, Banesh Hoffmann is capable of writing:
“How much more, then, shall we marvel at the wondrous powers of God who created the heaven and the earth from a primal essence of such exquisite subtlety that with it he could fashion brains and minds afire with the divine gift of clairvoyance to penetrate his mysteries. If the mind of a mere Bohr or Einstein astound us with its power, how may we begin to extol the glory of God who created them?” 3
Unfortunately, this is not an isolated example. A great part of modern literature about science, including a lot written by scientists themselves, is thoroughly impregnated with such mystical, religious or quasi-religious notions. This is a direct result of the idealist philosophy, which a great many scientists, consciously or unconsciously, have adopted.
The laws of quantum mechanics fly in the face of “common sense” (i.e., formal logic), but are in perfect consonance with dialectical materialism. Take, for example, the conception of a point. All traditional geometry is derived from a point, which subsequently becomes a line, a plane, a cube, etc. Yet close observation reveals that the point does not exist.
The point is conceived as the smallest expression of space, something that has no dimension. In reality, such a point consists of atoms—electrons, nuclei, photons, and even smaller particles. Ultimately, it disappears in a restless flux of swirling quantum waves. And there is no end to this process. No fixed “point” at all. That is the final answer to the idealists who seek to find perfect “forms” which allegedly lie “beyond” observable material reality. The only “ultimate reality” is the infinite, eternal, ever-changing material universe, which is far more wonderful in its endless variety of form and processes than the most fabulous adventures of science fiction. Instead of a fixed location—a “point”—we have a process, a never-ending flux. All attempts to impose a limit on this, in the form of a beginning or an end, will inevitably fail.
Disappearance of matter?
Long before the discovery of relativity, science had discovered two fundamental principles—the conservation of energy and the conservation of mass. The first of these was worked out by Leibniz in the 17th century, and subsequently developed in the 19th century as a corollary of a principle of mechanics. Long before that, early man discovered in practice the principle of the equivalence of work and heat, when he made fire by means of friction, thus translating a given amount of energy (work) into heat. At the beginning of this century, it was discovered that mass is merely one of the forms of energy. A particle of matter is nothing more than energy, highly concentrated and localised. The amount of energy concentrated in a particle is proportional to its mass, and the total amount of energy always remains the same. The loss of one kind of energy is compensated for by the gain of another kind of energy. While constantly changing its form, nevertheless, energy always remains the same.
The revolution effected by Einstein was to show that mass itself contains a staggering amount of energy. The equivalence of mass and energy is expressed by the formula E = mc2 in which c represents the velocity of light (about 186,000 miles per second), E is the energy that is contained in the stationary body, and m is its mass. The energy contained in the mass m is equal to this mass, multiplied by the square of the tremendous speed of light. Mass is therefore an immensely concentrated form of energy, the power of which may be conveyed by the fact that the energy released by an atomic explosion is less than one tenth of one per cent of the mass converted into energy. Normally this vast amount of energy locked up in matter is not manifested, and therefore passes unnoticed. But if the processes within the nucleus reach a critical point, part of the energy is released, as kinetic energy.
Since mass is only one of the forms of energy, matter and energy can neither be created nor destroyed. The forms of energy, on the other hand, are extremely diverse. For example, when protons in the sun unite to form helium nuclei, nuclear energy is released. This may first appear as the kinetic energy of motion of nuclei, contributing to the heat energy from the sun. Part of this energy is emitted from the sun in the form of photons, containing particles of electromagnetic energy. The latter, in turn, is transformed by the process of photosynthesis into the stored chemical energy in plants, which, in turn, is acquired by man by eating the plants, or animals which have fed upon the plants, to provide the warmth and energy for muscles, blood circulation, brain, etc.
The laws of classical physics in general cannot be applied to processes at the subatomic level. However, there is one law that knows no exception in nature—the law of the conservation of energy. Physicists know that neither a positive nor a negative charge can be created out of nothing. This fact is expressed by the law of the conservation of electric charge. Thus, in the process of producing a beta particle, the disappearance of the neutron (which has no charge) gives rise to a pair of particles with opposed charges—a positively charged proton and a negatively charged electron. Taken together, the two new particles have a combined electrical charge equal to zero.
If we take the opposite process, when a proton emits a positron and changes into a neutron, the charge of the original particle (the proton) is positive, and the resulting pair of particles (the neutron and positron), taken together, are positively charged. In all these myriad changes, the law of the conservation of electrical charge is strictly maintained, as are all the other conservation laws. Not even the tiniest fraction of energy is created or destroyed. Nor will such a phenomenon ever occur.
When an electron and its anti-particle, the positron, destroy themselves, their mass “disappears”, that is to say, it is transformed into two light-particles (photons) which fly apart in opposite directions. However, these have the same total energy as the particles from which they emerged. Mass-energy, linear momentum and electric charge are all preserved. This phenomenon has nothing in common with disappearance in the sense of annihilation. Dialectically, the electron and positron are negated and preserved at the same time. Matter and energy (which is merely two ways of saying the same thing) can neither be created nor destroyed, only transformed.
From the standpoint of dialectical materialism, matter is the objective reality given to us in sense perception. That includes not just “solid” objects, but also light. Photons are just as much matter as electrons or positrons. Mass is constantly being changed into energy (including light—photons) and energy into mass. The “annihilation” of a positron and an electron produces a pair of photons, but we also see the opposite process: when two photons meet, an electron and a positron can be produced, provided that the photons possess sufficient energy. This is sometimes presented as the creation of matter “from nothing”. It is no such thing. What we see here is neither the destruction nor the creation of anything, but the continuous transformation of matter into energy, and vice versa. When a photon hits an atom, it ceases to exist as a photon. It vanishes, but causes a change in the atom—an electron jumps from one orbit to another of higher energy. Here too, the opposite process occurs. When an electron jumps to an orbit of lower energy, a photon emerges.
The process of continual change that characterises the world at the subatomic level is a striking confirmation of the fact that dialectics is not just a subjective invention of the mind, but actually corresponds to objective processes taking place in nature. This process has gone on uninterruptedly for all eternity. It is a concrete demonstration of the indestructibility of matter—precisely the opposite of what it was meant to prove.
"Bricks of matter"?
For centuries, scientists have tried in vain to find the “bricks of matter”—the ultimate, smallest particle. A hundred years ago, they thought they had found it in the atom (which, in Greek, signifies “that which cannot be divided”). The discovery of subatomic particles led physics to probe deeper into the structure of matter. By 1928 scientists imagined that they had discovered the smallest particles—protons, electrons and photons. All the material world was supposed to be made up of these three. Subsequently, this was shattered by the discovery of the neutron, the positron, the deuteron, then a host of other particles, ever smaller, with an increasingly fleeting existence—neutrinos, pi-mesons, mu-mesons, k-mesons, and many others. The life span of some of these particles is so evanescent—maybe a billionth of a second—that they have been described as “virtual particles”—something utterly unthinkable in the pre-quantum era.
The tauon lasts only for a trillionth of a second, before breaking down into a muon, and then to an electron. The neutral pion is even more fleeting, breaking down in less than one quadrillionth of a second to form a pair of gamma rays. However, these gammas live to a ripe old age compared to others, which have a life of only one hundredth of a microsecond. Other particles, like the neutral sigma particle, break down after a hundred trillionth of a second. In the 1960s, even this was overtaken by the discovery of particles so evanescent that their existence could only be determined from the necessity of explaining their breakdown products. The half-lives of these particles are in the region of a few trillionths of a second. These are known as resonance particles. And even this was not the end of the story.
Over a hundred and fifty new particles were later discovered, which have been called hadrons. The situation was becoming extremely confused. An American physicist, Dr. Murray Gell-Mann, in an attempt to explain the structure of subatomic particles, postulated still other, more basic particles, the quarks, which were yet again heralded as the “ultimate building-blocks of matter”. Gell-Mann theorised that there were six different kinds of quarks and that the quark family was parallel to a six-member family of lighter particles known as leptons. All matter was now supposed to consist of these twelve particles. Even these, the most basic forms of matter so far known to science, still possess the same contradictory qualities we observe throughout nature, in accordance with the dialectical law of the unity of opposites. Quarks also exist in pairs, and possess a positive and negative charge, although it is, unusually, expressed in fractions.
Despite the fact that experience has demonstrated that there is no limit to matter, scientists still persist in the vain search for the “bricks of matter”. It is true that such expressions are the sensational inventions of journalists and some scientists with an over-developed flare for self-promotion, and that the search for ever smaller and fundamental particles is undoubtedly a bona fide scientific activity, which serves to deepen our knowledge of the workings of nature. Nevertheless, one certainly gets the impression that at least some of them really do believe that it is possible to reach a kind of ultimate level of reality, beyond which there is nothing left to discover, at least at the subatomic level.
The quark is supposed to be the last of twelve subatomic “building blocks” are said to make up all matter. Dr. David Schramm was reported as saying “The exciting thing is that this is the final piece of matter as we know it, as predicted by cosmology and the Standard Model of particle physics. It is the final piece of that puzzle'.” 4
So the quark is the “ultimate particle”. It is said to be fundamental and structureless. But similar claims were made in the past for the atom, then the proton, and so on and so forth. And in the same way, we can confidently predict the discovery of still more “fundamental” forms of matter in the future. The fact that the present state of our knowledge and technology does not permit us to determine the properties of the quark does not entitle us to affirm that it has no structure. The properties of the quark still await analysis, and there is no reason to suppose that this will not be achieved, pointing the way to a still deeper probing of the endless properties of matter. This is the way science has always advanced. The supposedly unbreachable barriers to knowledge erected by one generation are overturned by the next, and so on down the ages. The whole of previous experience gives us every reason to believe that this dialectical process of the advance of human knowledge is as endless as the infinite universe itself.
1. Hoffmann, B. The Strange Story of the Quantum, p. 147.↩
2. Engels, F. Dialectics of Nature, p. 92.↩
3. Hoffmann, B. op. cit., pp. 194-5.↩
4. Financial Times, 1/4/94, our emphasis.↩