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From Fourth International, Vol. II No. 1, January 1941, pp. 29–30.
Transcribed & marked up by David Walters for ETOL.
MATTER AND LIGHT
By Louis De Broglie, Professeur à la Faculté des Sciences de Paris.
300 pp. W.W. Norton & Co., New York.
Matter and Light is a study or the new Wave Mechanics, bearing directly upon the present major crisis in modern physics. Contrary to what one might expect of a book on physics, no mathematics is required – except for two chapters, which the author advises “can be omitted without prejudice to an understanding of the rest of the book.” Despite the highly abstract nature of the subject, it is an intriguing account of the scientist’s struggle to maintain a grasp upon ever-elusive reality.
In this struggle there is no rest. As, on the one hand, experimental technique becomes perfected, on the other hand reality reveals itself to be infinitely complex.
Physicists are continually encountering new and more perplexing phenomena, which require fresh explanations.
The problems arising from recent experimental results have led to the development of the new Wave Mechanics. Wave Mechanics in turn has thrown modern physical theory into a state of crisis. “It Is a severe crisis,” writes De Broglie, “and it has shaken the entire ancient structure of our scientific knowledge. And it seems certain that this major crisis ... will be the source of philosophical consequences which cannot yet be clearly perceived.” What most physicists, including De Broglie, cannot yet clearly perceive will be far clearer to a dialectical materialist. The prediction Engels made in 1885 (in the preface to the second edition of his Anti-Duehring), regarding the development of theoretical natural science, is now being strikingly confirmed in many branches of physics. “The revolution which is forced upon theoretical natural science by the very necessity of giving orderly arrangement to the immense accumulation of empirical discoveries is of such a kind that it must bring the dialectical character of the natural processes to the consciousness even of the most resisting empiricists. The old rigid antitheses, the sharp insurmountable lines of demarcation, vanish more and more ... At all events, natural science is now so far advanced that it can no longer escape from the dialectical embrace.” In every chapter of Matter and Light nature seems to be clamoring for a conscious recognition of its dialectical character. Certain of the author’s own statements actually express, though in a concrete rather than general form, fundamental propositions of the materialist dialectic.
The relativity of our knowledge is expressed in the evolution of the new Wave Mechanics out of the obstacles encountered by the old Newtonian mechanics. Newtonian mechanics was supposed to be universal, to apply to all modes of motion. But its laws were found to be inapplicable to two extreme types of motion: high astronomical velocities and the motion of material particles inside the atom. The first contradiction led to the creation of Einstein’s relativity theory. The second resulted in Wave Mechanics.
Does this mean that Newtonian mechanics is completely useless for physics now that it has been supplanted by these more developed theories? No. Its sphere of application has been circumscribed; its truth shown to be relative, limited. “Newtonian mechanics undeniably succeeds in predicting exactly motion occurring on the human scale, and also on the scale of celestial bodies; and the reason for this is that, for Wave Mechanics, Newtonian mechanics Is an entirely adequate approximation. But when it comes to investigating the motion of the material particle inside the atom, the old mechanics ceases to have any value, while the new one allows us to grasp the sense of the new principles which the Quantum Theories were obliged to introduce.” The old mechanics was based upon the notion that waves and corpuscles were irreconcilable opposites. Light, for example, had either to be corpuscular in nature, as Newton contended, or wavelike, as Huygens had argued. Which was right? There was experimental evidence favoring both sides and so the dilemma, perplexed physicists for several centuries.
The new mechanics surmounted this Seemingly Insoluble contradiction in a thoroughly dialectical manner: by means of the unity of opposites. It took as its starting point the denial of the unbridgeable distinction between waves and corpuscles. It affirmed, on the contrary, that these opposites were identical!
Let us listen to De Broglie on this point. “In the theory of Matter, as in the theory of radiation, it was essential to consider corpuscles and waves simultaneously if it were desired to reach a single theory, permitting of the simultaneous interpretation of the properties of Light and of those of Matter. It then becomes clear at once that, in order to predict the motion of a corpuscle, it Is necessary to construct a new Mechanics. In which the motion of a corpuscle is inferred from the motion in space of a wave ... Meanwhile it will no longer be possible to consider the material corpuscles, electrons and protons, in isolation; it will, on the contrary, have to be assumed in each case that they are accompanied by a wave which is bound up with their own motion.” And De Broglie, one of the chief authors of Wave Mechanics, was able to state In advance “the wavelength of the associated wave belonging to an electron having a given velocity.” Then De Broglie discovered at one stroke the law of the transformation of quantity into quality and the transformation of things into their opposites. “In proportion as the quantum of radiation increases, new properties appear; a fact which would become exceedingly important if the principle were to be confirmed that radiation, whose quantum exceeds twice the absolute energy corresponding to the mass of the electron, can become transformed into two electrified corpuscles of opposite sign.” In the old physical theory matter and light were treated as opposites. Now they are seen to have “a far greater structural resemblance between them than had formerly been suspected.” The physics of matter and the physics of radiation have now, each, been invaded by the aspect of the other, first “the corpuscle invaded the wave aspect of Light“; and now “the wave has invaded the corpuscular aspect of Matter.” Here is objective evidence of the dialectical law of the interpenetration of opposites, all the more valuable because it is presented by De Brogue in an involuntary and unconscious manner.
De Broglie is a physicist, not a philosopher, obviously puzzled by the general theoretical problems raised by the recent developments in physics and incapable of solving them. His confusion and helpnessnesa reflect the bankruptcy of the old philosophical schools tied up with capitalist society.
By proceeding dialectically the creators of wave mechanics were able to rescue physics from one blind alley. Now, unless they acquire the instrument of dialectical materialism, they run the risk of landing in another. The dialectical character of the historical process manifests itself as clearly and forcibly in nature as in society. In view of this inability of bourgeois philosophies to overcome the crisis of modern physics, scientists have nothing to lose in adopting the philosophy of dialectical materialism and they have the world to gain!
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