Physics

PHYSICS, a science that, together with chemistry, studies the general laws of the transformation of energy and matter. At the foundation of both sciences lie two basic laws of natural science—the law of conservation of mass (the law of Lomonosov, Lavoisier) and the law of conservation of energy (R. Mayer, Joule, and Helmholtz). In earlier times, physics referred to those transformations in which the composition of the substance does not change. Chemical transformations were considered those in which the substance undergoes deep changes during the process. Later, transitions were pointed out where physical and chemical phenomena were closely intertwined with each other, and therefore, a demarcation between physical and chemical phenomena appears impossible at the present time. During the historical development of physics, a whole series of departments were distinguished, which carried an independent character without connection to neighboring fields, and initially, in the division of physics, a large role was played by sensations received by our sense organs during the perception of natural phenomena. Thus, the study of sound, the study of light, the study of heat, etc., were distinguished. All of physics was divided into a series of independent fields, among which the main one was mechanics, which, thanks to the coherent system created by Newton, represented the type of exact science that derived all provisions from three axioms or laws of motion. Along with the motion of a point, studied by Newton, the motion of a system of points, the motion of an ideal solid body, and the motion of liquids and gases without friction were subsequently studied. At the same time, both solid bodies and liquids and gases were represented as continuous, devoid of internal structure. The study of mechanical processes underlying acoustic phenomena led physics to the creation of a mathematical theory of sound, which was a further development of mechanics (aero- and hydrodynamics). Theoretical studies of wave processes showed the existence of diffraction and interference in sound waves, carefully studied by experiment. Experiments further discovered interference and diffraction in light processes, bringing optics and acoustics closer together. Thus, it was natural to assume the existence of a special material medium, the ether, in which waves associated with light phenomena arise. Using the speed of light processes, even calculations of the density and elasticity of the ether were made. These calculations showed that the ether must be a body whose density is significantly less than the densities of known gases in their most rarefied state and whose elasticity must significantly exceed the elasticity of steel. The discovery of the polarization (see) of light, associated with the transversality of light oscillations, led to further analogies of the properties of the ether with the properties of a solid body. It was possible to think that optical phenomena could be entirely explained by mechanics, which began to be viewed as the basis of every exact science, creating a rational explanation of phenomena. The appearance of the rudiments of the kinetic theory of gases (see Kinetic theory) allowed one initially to think that phenomena in a gaseous medium could also be explained by resorting exclusively to mechanical laws. The creation of the mechanical theory of heat, which linked mechanical processes in a body with thermal processes, further strengthened the confidence in the universal significance of mechanics. Experiments in the field of electricity forced physicists to assume the existence of a connection between optical phenomena and electrical phenomena. We find a deep analysis of electrical and light phenomena in the immortal work of Maxwell, where it is shown that electromagnetic disturbances propagate in a medium with a speed equal to the ratio of electromagnetic and electrostatic units. This ratio is equal to the speed of light. Electromagnetic processes and light processes appear to be phenomena of the same kind, occurring in the same medium, so that one could speak of the electromagnetic nature of a light ray. Thus, the electromagnetic theory of light was created, in which the light process and the process of propagation of electromagnetic induction, caused by the opening and closing of a current, are reduced to phenomena in the ether, differing only quantitatively. If initially connections were established between acoustics and optics and one could think about a mechanical interpretation of light phenomena, then the studies of Maxwell, Hertz, Lebedev, Rubens, and others (light pressure, reflection of infrared waves from metals) forced one to consider that only the kinematic side of the phenomena, associated with the wave-like nature of the process, is the same for sound and light. The essence of the optical process is connected with electromagnetic phenomena occurring in the ether. Physics at this time is divided into the physics of matter and the physics of the ether. The study of the motion of matter in the ether leads researchers to a series of contradictions, usually denoted in the history of the question as the period of the crisis of the theory of the ether. At this time, the theory of the stationary ether, not dragged along by moving matter, arises; the famous system of Lorentz transformations is established, leading to ideas about the contraction of moving bodies. This movement of science concludes with the establishment of the principle of relativity (Einstein), which shows that, if one takes into account all experiments on light processes occurring in moving bodies, one must admit that, while on a body moving rectilinearly and uniformly, it is impossible to establish whether the body is in motion or at rest. This leads to the recognition of such properties of the ether that we cannot at all connect with the idea of any substance. In contrast to all experiments known from acoustics, the speed of light must be independent of the state of rest or motion of the observer. The principle of relativity gave the greatest generalizations of mechanics, showing, firstly, that a body changes its shape during motion, that time on a moving body is different than on a stationary one, that energy is equivalent to the mass of the body, so that each mass is connected with a certain reserve of energy and energy carries with it a certain mass. The connection between energy E, mass m, and the speed of light c is expressed by the formula: m = E/c². Finally, the principle of relativity establishes the change in mass during its motion with velocity v, in the form m = m₀ / sqrt(1 - v²/c²), where m₀ is the rest mass. Further studies by Einstein allowed generalizing the aforementioned small or special principle of relativity and establishing that all motions in nature are relative. The generalized principle of relativity leads, firstly, to the explanation of the phenomenon of the motion of the perihelion of Mercury, to the establishment of the attraction of a light ray by heavy bodies, and to the establishment of the shift of spectral lines of the red part of the spectrum under the influence of gravity. All conclusions of the generalized principle of relativity received experimental confirmation. The study of thermal processes led to the establishment of two principles of thermodynamics, which reduced the tasks of the theory of heat to mathematical problems. Thermodynamics, with its rigor and consistency, received the same form as Newtonian mechanics, which derived all phenomena of motion from 3 basic laws. The development of thermodynamics allowed applying its principles to questions of radiation and thus finding the relationships characterizing the phenomena of light emission. Studies of the total integral radiation of an absolutely black body established the connection between the absolute temperature T of the body and the amount of heat Q lost by 1 cm² of its surface per unit of time in the form Q = σT⁴ (σ is a constant). It was possible to think that the further application of thermodynamics and electrodynamics would allow solving the question of radiation completely, making it possible to theoretically find the distribution of energy in the spectrum. However, all attempts to apply thermodynamics and electrodynamics to this question did not lead to anything, and Planck showed that the task can be solved if we assume that radiation does not occur in the form of a continuous system of waves, but arises as a result of the emission by heated bodies of small portions of energy, so-called quanta, or photons. If we denote by q the amount of energy in a given quantum, by h the constant, and by ν the number of light oscillations, then the relation is obtained: q = hν. With Planck's studies, statistical principles are introduced into the theory of light for the first time. The quantum theory, expanded by Einstein, created a new department of physical statistics—the theory of atoms of light energy. A huge number of discoveries made since the moment Planck established the foundations of the quantum theory testifies to the extraordinary fruitfulness of the ideas of Planck and Einstein. The laws of the photoelectric effect, the laws of fluorescence and phosphorescence, the Compton effect, the Raman effect, the specific heats of solid bodies at low temperatures (Nernst), and finally the theory of the structure of the atom, developed by Bohr, show what vast and important departments of physics Planck's idea of the atomism of light processes brought to light. From this moment, a dualism begins in the theory of light, which did not allow for a single, general explanation of all optical phenomena. Phenomena of reflection, refraction, interference, diffraction, and polarization in all its forms could be explained, starting from the idea of light as a wave process.

The phenomenon of radiation, the photoelectric effect, the Compton effect, the Raman effect, specific heats at low temperatures, and the structure of the atom are explained by the assumption of a corpuscular structure of light. The corpuscular and wave theories of light were united by the remarkable works of de Broglie, Schrödinger, Heisenberg, and Dirac, who showed that behind light phenomena, as well as behind all other material phenomena of nature, one must recognize a duality: on the one hand, every process possesses a wave nature; on the other hand, there is everywhere a corpuscular process existing simultaneously with the wave. For light, we have two processes propagating at the same speed: the photon and the wave, moving in space not occupied by matter at a speed of 300,000 km/sec. The movement of material particles—atoms, electrons—is also accompanied by the movement of waves, and the slower the movement of the electron, the faster the wave moves; in general, the waves accompanying electrons move faster than light. Brilliant experimental studies have shown that matter, like light, along with corpuscular properties, also possesses wave properties. These works completed a grandiose synthesis of the doctrine of light and matter, creating a new field of Physics—wave mechanics, or new quantum mechanics. Along with the enormous successes of theoretical research in the field of Physics, from the end of the last century begins the flourishing of the experimental study of physical phenomena, the beginning of which was laid by the discovery of the electron in cathode rays (Crookes, Lenard, J. Thomson) and the proof of its existence in the atom emitting light (Lorentz, Zeeman). The discovery of X-rays by Röntgen and the discovery of radioactive phenomena by Becquerel, the Curies, and Rutherford created a new era in Physics. In the history of science, it was discovered for the first time that the atoms of radioactive element series transform into one another. In the end, the radioactive elements of the radium series and the thorium series transform into non-radioactive ones (into lead). During the investigation of radioactivity, it was possible for the first time to prove that atoms of one and the same element (lead) can have different atomic weights. At the present time, it has been proven that atoms of one specific element in most cases have different weights; atoms with identical chemical properties but different atomic weights are called isotopes. The systematic study of isotopes was prepared by the brilliant works of Thomson on positive electricity rays and was further developed by Aston. In the light of new studies of isotopes, incomprehensible facts in the periodic system of elements, known even to Mendeleev himself and which had not yielded to explanation before the establishment of the doctrine of isotopes, receive their explanation. Beginning in 1918, under the influence of the development of the electron theory and the theory of atomic structure, there arise deep, epoch-making studies by Rutherford on the artificial decomposition and transmutation of atoms. By bombarding atoms with alpha-rays of radioactive bodies [see Alpha (α)-rays], Rutherford succeeded in transforming some elements into others (nitrogen into hydrogen) and laying the foundation for a new science—the chemistry of the atomic nucleus, which deals with the artificial transmutation of elements. The studies carried out on atoms disintegrating under the influence of alpha-rays led to the discovery of artificial radioactivity (Curie and Joliot) and to the establishment of elements lying further than uranium in Mendeleev's periodic system (Fermi). Spectral analysis of X-rays has allowed, at the present time, the finding of missing elements of the periodic system. The study of the transmutation of atoms into one another leads in the end to the recognition that all matter is built from electrons, which carry a negative charge and have a small mass; from protons, which have a positive charge and a mass equal to the mass of a hydrogen nucleus; from neutrons, which have no charge and have a mass equal to the mass of a proton; and finally, from positrons, which have a positive charge and a mass equal to the mass of an electron. The development of Physics over the last 50 years has created a number of new fields in which Physics is applied to the explanation of more complex phenomena of nature. Crystal physics is being created, encompassing the study of crystalline matter. In this field, especially great successes have been made recently thanks to the application of X-rays for the discovery of crystalline structures. The application of Physics to the investigation of phenomena occurring in the Earth creates geophysics, wherein, along with processes occurring in the gaseous and liquid shell of the Earth, processes in the solid body of the Earth are investigated. The application of physical methods to the study of the structure of the solid shell of the globe leads to remarkable practical applications of physical methods—to the search for ore deposits. The application of Physics to processes occurring in world space creates a new branch of science—astrophysics. Besides the study of the chemical structure of the most distant stellar systems, their movement, dimensions, distance from the Earth, and their gradual evolution, leading to concepts of cosmogony, are studied. The application of modern doctrines of Physics to biological processes creates a new science—biophysics, in which the applications of the laws of mechanics to the movement of the organism and its parts are studied, as well as the application of thermodynamics to the study of the metabolism of organs and whole organisms, and the application of the doctrine of solutions and colloids to the division of the egg and to phenomena of tissue excitation (see Parthenogenesis and Ionic theory of excitation). A separate, extensive field of biophysics is the study of radiation resulting from the functioning of tissues and organs and the division of cells (see Mitogenetic rays). Finally, physics has a direct application in the field of scientific and practical medicine (see Medicine). A whole series of diagnostic techniques (auscultation, percussion, X-ray diagnostics, etc.) and therapeutic interventions (electrotherapy, phototherapy, X-ray and radiotherapy, etc.) are based on the laws of Physics. P. Lazarev. However, despite the discoveries of enormous importance, despite the spontaneous materialism of the majority of outstanding physicists, modern Physics in capitalist countries is experiencing a deep crisis. Idealistic and mystical currents in bourgeois science, characteristic of the period of the decay of capitalism, are penetrating into the field of Physics as well. Among bourgeois physicists, the ideas of Mach still have wide circulation, the idealistic character of which was brilliantly exposed by Lenin in his remarkable work "Materialism and Empirio-criticism." If Mayer and other founders of modern Physics rose to a dialectical understanding of individual questions, then some modern scientists are attempting to use quantum theory and the theory of relativity for attacks on materialism, for preaching the denial not only of matter but also of space and time, the law of the transformation of energy, etc. With the blessing of Mach and other idealists, they preach that the world is a "complex of sensations," that the "materialistic concept of the world has been overcome," they speak of the "disappearance of matter," and so on. Meanwhile, all the laws of Physics and all discoveries in the field of Physics brilliantly confirm the correctness of the theory of dialectical materialism. Physics always operates with matter, i.e., with that which exists independently of our consciousness and acts upon our sense organs. All the newest discoveries in the field of Physics do not "overcome" matter but only modify our ideas about it; matter remains an "objective reality existing independently of human consciousness and reflected by it" (Lenin). "It is impossible now to take into one's hands almost any theoretical book on natural science," wrote Engels, "without becoming convinced that the natural scientists themselves understand how they suffer from this confusion and incoherence, to which the fashionable, if one may say so, philosophy gives them absolutely no way out. And here there is no other real way out, no possibility of achieving clarity without a return in one form or another from metaphysical thinking to dialectical" ("Dialectics of Nature"). Brilliantly utilizing the method of dialectical materialism, Engels gave instructions on such cardinal questions of Physics as the dialectical concept of the unity and difference of various forms of motion, the understanding of motion as change in general, the concept of causality and interaction, the kinetic theory, the concept of force, the Clausius law of thermodynamics, etc. A way out of the crisis of Physics is possible only along the paths of dialectical materialism. It is precisely along these paths that physical science is widely developing in the USSR. Physics in history was born and developed from the demands of production; it unfolded in connection with technology. The struggle against technology in capitalist countries in the era of the current crisis has also hit the development of Physics in these countries. Conversely, the rapid growth of the socialist economy in the USSR presents ever new demands to Physics and chemistry. Both socialist industry and socialist agriculture provide a social mandate to physics and chemistry. For their part, the successes of Physics and chemistry dialectically influence the successes of the development of industry and agriculture. Physics and chemistry have been placed at the service of the construction of socialism. "Modern physics is in labor. It is giving birth to dialectical materialism," wrote Lenin. In the USSR, these "labor pains" are an accomplished fact.

Physical sciences in our country have firmly taken the position of dialectical materialism and have become inextricably linked with the needs of production. This circumstance has made the USSR a leading country in the world in terms of the development of scientific institutions and the scale of work in the field of physics.