Original version of the slightly shortened text published in French translation under the title Stabilité et développement dans les sciences de la nature in La Pensée, no. 213–14 (1980), 114–31. The English version presented here was published with minor changes in Marxism, Science and the Movement of History, edited by A. R. Burger, H. R. Cohen, and David H. DeGrood (Amsterdam, B. R. Gruener, 1980), 77–104.
Stability and Development in Physical Science
In the developed capitalist countries very little has been written on the physical sciences by scientists and philosophers who consciously base their work on dialectical-materialist methods of analysis. A principal reason for this absence lies in the academic and administrative harassment and discrimination to which dialectical materialists are subjected in the academic life of these countries. A second reason is the almost complete separation of philosophy from science in the professional training of physical scientists. Theoretical textbooks and the instructors using them rarely identify the philosophical approaches on which they are based and these approaches are certainly not likely to be dialectical materialist. Philosophical concepts such as operational definitions are simply presented as part of the rules of the particular science. Finally, with rare exceptions, a student in the physical sciences with an interest in dialectical materialism is not going to be able to find courses illustrating its application to his major field of study. Since the integrated philosophical structure of dialectical materialism is so different from the philosophies to which students are exposed from the very beginning of their elementary education, it essentially requires a second academic specialization outside the educational system of the university in order to acquire competence in the conscious application of dialectical-materialist methods in one’s professional work.
When the research experience of scientists leads them to adopt what are essentially dialectically-materialist methods in one or another aspect of their work, they generally do not recognize this philosophical content, and the prevailing hostility toward the philosophical system itself does not encourage such scientists to examine consciously the philosophical content of their work.
In a recent series of articles, physicist Pierre Jaeglé and biologist Pierre Roubaud,1,2,3 both of whom collaborate closely with the Centre d’Etudes et de Recherches Marxistes in Paris, suggest a different reason for the reluctance of scientists to adopt dialectical materialism as the basic philosophical methodology in their work. Jaeglé and Roubaud suggest that the relationship between Marxism and science has suffered because of a confusion that arose between the history of nature and the science of nature. They see this confusion as an inevitable consequence of the pioneering nature of Engels’ work on the dialectics of nature. The metaphysical viewpoint of an unchanging society, which Marx and Engels combated, had its counterpart in the view that the world of nature was fixed and unchanging. A revolutionary movement could not be indifferent to the ideological consequences of such a viewpoint and Engels felt it necessary to demonstrate the existence of a historical dimension in the world of nature, as Marx and he had done in the case of society. Jaeglé and Roubaud attribute to this focus on historical process what they say is Engels’ failure to make a distinction between the science of nature and the materialist history of nature. A consequence of this failure was the subsequent development of dogmatic tendencies in the Marxist approach to the science of nature, which expressed itself in the inability to recognize the importance of invariance in nature. “Invariance,” write Jaeglé and Roubaud, “is the essence of scientific knowledge inasmuch as it permits change to be understood and mastered. . . . Scientific knowledge is formed (se constitue) in a process of negation of historicity” (III). By negation of historicity, Jaeglé and Roubaud mean that the subject matter of a science of nature is universal laws that are independent of history, laws that are equally valid yesterday, today, and tomorrow. On the other hand, they see knowledge of these laws as providing the means of understanding the historical development of the world of nature. Therefore the science of nature has to be distinguished from the history of nature.
In this spirit, Jaeglé and Roubaud see the great progress in biology and physics to be associated with the discoveries of invariances. As examples they cite, among others, genetic invariance and conservation of energy.
In this analysis I will show that the concept of dialectical change is broader than the concept of history and that one cannot set invariance in opposition to change to understand the nature of scientific activity. In discussing the views of Jaeglé and Roubaud, I will be drawing on some of the very abundant literature available in the socialist countries on philosophical methodology in the natural sciences, very little of which is at present available in the English language. Since my own academic training is in the physical sciences, I will draw heavily on materials from that field and use this opportunity to demonstrate the necessity of the conscious application of dialectical-materialist methods for discussing the conceptual foundations of the physical sciences.
Engels and the Law of Conservation of Energy
Since Jaeglé and Roubaud single out Engels’ comments the law of conservation of energy as a principal source of what they argue is a confusion between the science of nature and the history of nature, it is important to examine in detail some of Engels’ comments on the question. In his 1885 preface to Anti-Dühring, Engels wrote:
Although ten years ago the great basic law of motion, then recently discovered, was as yet conceived merely as a law of the conservation of energy, as the mere expression of the indestructibility and uncreatability of motion, that is, merely in its quantitative aspect, this narrow, negative conception is being more and more supplanted by the positive idea of the transformation of energy, in which for the first time the qualitative content of the process comes into its own, and the last vestige of a creator external to the world is obliterated.4
Referring to this, passage, Jaeglé and Roubaud comment that Engels, by identifying the dialectical with the historical, relegated the aspect of conservation in a process to a position of secondary importance. They say that Engels wished to see as new only the transformation of energy from one form to another, while the entire experimental and theoretical effort of tile preceding one hundred and fifty years was to find what was conserved in the transformation. They conclude: “Strange situation that the category of matter is elaborated thanks to the discoveries of mechanics, but the latter is dismissed because it has not passed the examination of dialectics” (III).
First of all, it is not true that Engels identified the dialectical with the historical. For Engels, materialist dialectics embraces more than just the historical. In fact, the transformation of energy, say from mechanical to electrical energy, can often be treated as a reversible process and therefore does not fall into the category of history even by the criteria of Jaeglé and Roubaud.
In his notes for the unfinished Dialectics of Nature, Engels recorded the following:
Conservation of Energy. — The quantitative constancy of motion was already enunciated by Descartes, and indeed almost in the same words as now. . . . On the other hand, the transformation of form of motion was only discovered after 1842 and this, not the law of quantitative constancy, is what is new.5
Engels had in mind here the debates about conserved quantities in mechanics that began in the 17th century. Leibniz’s quarrel with the Cartesians was not on whether the quantity of motion was conserved, but on the mathematical expression of that quantity. By the middle of the 19th century, the relationship between momentum and energy as conserved quantities in mechanics had become clear, and the mathematical expressions for work and the various forms of energy (kinetic, thermal, etc.) were established with the aid of the newly formulated law of conservation of energy. Engels, on the other hand, drew attention to the fact that no one had offered a qualitative explanation of the quantity that was being conserved and thus the connection between work and energy remained unclear. He points out that “Helmholtz’s lectures On the Conservation of Force (1862), which was intended precisely ‘to make as clear as possible the fundamental physical concepts of work and their invariability’” failed to do just that. Engels comments:
All that we learn there about work is: that it is something which is expressed in foot-pounds or in units of heat, and that the number of these foot-pounds or units of heat is invariable for a definite quantity of work. . . . The concept of work is neither developed, nor even defined. . . . And so Helmholtz can go so far as to assert that “friction and inelastic impact are processes in which mechanical work is destroyed and heat is produced in-stead.” Just the contrary. Here mechanical work is not destroyed, here mechanical work is performed. It is mechanical motion that is apparently destroyed. But mechanical motion can never perform even a millionth part of a kilogram-metre of work, without apparently being destroyed as such, without becoming converted into another form of motion.6
In a footnote to this discussion, Engels noted that one gets no further by consulting James Clerk Maxwell, who, in his Theory of Heat (4th edition, 1975) wrote; “Work is done when resistance is overcome,” and The energy of a body is its capacity for doing work.”
Among other things, Engels is objecting to viewing a physical process merely as a correlation between two states connected only quantitatively. The passages of Helmholtz criticized by Engels are an expression of the inconsistency of Helmholtz’s materialism. He treats the appearance of heat as an emergent process that accompanies the disappearance of something else. Helmholtz had elegantly demonstrated the quantitative connections between the energies of systems undergoing transformation, but he did not consider the process as a process of transformation. In his commentaries on the law of conservation of energy, Helmholtz considered the forms of energy as qualitatively unconnected, each being due to a different force or ultimate cause of an unchangeable nature. At the same time, he believed that matter was composed of a fixed number of types of atoms or immutable elements to which it would be possible to apply Newton’s laws of motion in order to explain the effects of these forces on matter. For Helmholtz, force was only the “objectivized law of action” and the task of discovering the laws of mature was reduced to seeking out these ultimate forces.7 To this Engels commented:
Neither the law, when once established, not its objectivity, nor that of its action, acquires the slightest new objectivity by our interpolating a force into it; what is added is our subjective assertion that it acts in virtue of some so far entirely unknown force. . . . Just because we are not yet clear about the “rather complicated conditions” of these phenomena, we often resort here to the word force. We express thereby not our scientific knowledge, but our lack of scientific knowledge of the nature of the law and its mode of action.8
The ambiguity of Helmholtz’s concept of emergent forces without any other cause (since he considered them to be ultimate forces) can be readily seen by the facility with which the concept of emergence is utilized by modern forms of philosophical idealism, in particular by Karl Popper, who has made the denial of a material basis of consciousness one of his principal concerns:
We might find a recipe for creating some primitive forms of life from nonliving matter without understanding, theoretically, what we were doing. . . . If the situation is such that, on the one hand, living organisms may originate by a natural process from non-living systems, and that, on the other hand, there is no complete theoretical understanding of life possible in physical terms, then we might speak of life as an emergent property of physical bodies, or of matter. . . . 1 have dwelt on this point so long because it has some bearing on the position of the next rung of the ladder—the emergence of consciousness.9
Jaeglé and Roubaud overlook the magnitude of the task that Engels was confronting. Although Helmholtz was not the first to formulate the law of conservation of energy, it was largely his systematic mathematical analysis and extension to a wide variety of other forms of energy apart from mechanics that led to the acceptance of the law by the scientific community.10 His commentaries on the law, however, reflected his metaphysical (mechanistic) and neo-Kantian philosophical outlook. It was not until the beginning of the twentieth century that the mechanistic framework for interpreting the law was discarded, and then only partly. Engels’ commentaries, however, show an understanding of the law that is still not generally found even in current scientific literature. It still seems rather surprising that the great physical scientists of Engels’ time, such as Helmholtz and Maxwell, while able to perform every variety of calculation with the concepts of work and energy, were unable to explain the nature of these concepts, Engels not only was able to point out the philosophical source of the difficulty, but could produce a meaningful interpretation which is still valid today. “Work, therefore,” wrote Engels, “is change of form of motion regarded in its quantitative aspect.”11 Expressing the same idea in another way, Engels wrote: “it is precisely the quantitative invariability of the magnitude of work which prevents him [Helmholtz—E.M.] from realising that the qualitative alteration, the change of form, is the basic condition for all physical work.”12
Engels did not have a corresponding general formulation for the concept of energy, although he came close to it in the case of kinetic energy ½mv2 is mechanical motion measured by its capacity to become converted into a definite quantity of another form of motion.”13 In view of his other references to the reverse transformations and to transformations from one form of motion to another, we can formula the following statement on the concept of energy as consistent with Engels’ position at the time he was working on Dialectics of Nature: Energy is a measure of the capacity for change in the form of motion.
Energy as a general concept is usually not discussed in current physics textbooks or other books on physics, although the derivations of the mathematical expressions for its calculation for various forms of material systems are given. The picture that one usually encounters is that energy is that quantity which is conserved in the law of conservation of energy and somehow it is related to mechanical work.
In a rare discussion of the question, D. W. Theobald, in his book The Concept of Energy attributes the difficulty in formulating a concept of energy to the fact that energy is among the most fundamental physical concepts at our disposal. He does offer, however, the following formulation; “Energy is a measure of the capacity of a system for change.”14 This statement is indeed fairly close to that which we associated with Engels, although it still lacks the qualitative specification carried by the phrase change in the form.
We have seen above how a dialectical-materialist approach to the transformation of matter from one form to another contributes to a consistent understanding of the law of conservation of energy. We have seen inconsistencies in Helmholtz’s interpretation of the law, despite his great contribution to the development of its content. One should not overlook the fact that Mayer, whose discovery of the law predated Helmholtz’s announcement of his results by several years, had a more consistent understanding of the law, even though Helmholtz displayed greater mathematical ability in making it respectable and in demonstrating its universality.
It is not unusual in science for inconsistencies (philosophical or otherwise) in the work of one investigator to compensated for or overcome in the work of another. Dialectical materialism can provide a good insight on how philosophically unsound or eclectic mixtures of approaches lead to meaningful progress in science. At any one time, for example, we find physicists specializing in research on particular forms of matter: elementary particles, nuclear physics, atomic physics, molecular physics, statistical mechanics, continuum mechanics, etc. Overall, we are presented with a dialectical view of structurally connected levels of organization of matter, each with its own laws. Models that have essentially a mechanistic character, insofar as they deal with unchangeable forms of matter within a given level, can often provide highly useful results for a wide range of properties for that level. An example of this is the ideal gas laws of thermodynamics, even though every real gas deviates from them. A scientist conditioned to working with such models may, however, encounter a conceptual crisis when confronted with the necessity of finding connections between the laws of two levels if the connections do not lend themselves readily to a reductionist interpretation.
The relationships between objectively existing material systems and the transformations that occur between them have a clearly dialectical character. Practice has shown that researchers sooner or later discover them whether or not they are familiar with dialectical materialism or are willing to accept it as a method of analysis. The value of dialectical materialism as a philosophical method, and the only justification for its use, lies precisely in the fact that it corresponds to objective processes in the world outside us.
System Structures, Transformations, and Invariance
Let us now look at the assertion of Jaeglé and Roubaud that the tendency in Marxism to stress the element of change in nature led to a failure to recognize that invariance in nature is the key to our scientific understanding of it. The examples of invariance given by them cover a wide range: conserved physical quantities (energy, momentum, electric charge, etc.), invariant material structures (genes, particles), cyclical processes, and even the recurrent element in historical processes. In fact, they state that any quantity, if it is to be a physical quantity, has to exist as an invariant (I, II).
Let us first consider a dialectical-materialist view of material systems, physical quantities, and the laws that embrace them.
We will start with the concept of a system. What we say about a system should not, however, be considered to be a definition, but rather an elaboration of the concept without any claim to completeness. The same holds for the other basic concepts discussed below.
Blauberg, Sadovsky, and Yudin list the following features of a system: (l) a system is an integral complex of interconnected elements, (2) a system forms a special unity with its environment; (3) any investigated system is usually an element (or subsystem) of a higher-order system; and (4) elements of any system usually appear as systems of lower order.15 With these features a system constitutes an integrated whole of hierarchically interconnected relations and elements. The principles of wholeness and hierarchy assert the primacy of the system as a whole over its elements well as the fundamental hierarchical structure of the system.
The term structure is generally used to denote the stable aspect of a system. The stability of a system is always relative, determined as it is by the time interval over which the system’s elements and relations show no significant qualitative change (more on this to follow). Hörz, therefore, characterizes the structure of a system as “the totality of essential and unessential, general and particular, necessary and contingent relations between the elements of a system in a definite time interval.16
A system is a material system if its elements are material elements. (Theoretical systems are not material.)
Systems have properties. A property, according to Uyemov, is most simply defined as that which all things of a given class have in a common.17 This “definition,” however, is only a starting point for developing the concept of property. The concept of property is best grasped by considering its contradictory nature. Properties are what give a system or object its individual identity, distinguish it from other things and therefore characterize and affirm its objective existence. In this sense a material system stands distinct from and in opposition to its surroundings. On the other hand, a material system manifests its properties only in interaction with its surroundings, that is, in interaction with and relation to other material systems. The interconnection between these contradictory sides of a property of a material system provides a basis for the acquisition of objective knowledge about the system. The properties of a material system, manifesting themselves as phenomena, open the way for the theoretical investigation of the system. The system itself is not reducible, however, to the totality of phenomena associated with it. It is more accurate to say that a material system or object is nothing more than the totality of its properties, which are expressed through its interconnections with other things.
A physical quantity is a way of designating quantitatively and qualitatively a property of a physical system, or a part of it, or a relationship of the system (and its parts) to other systems. Thus the stiffness of a spring (a material body taken as a system) is a property associated with the internal structure of the spring. It manifests itself, however only upon being stretched by the application of an external force. A physical quantity can be defined exclusively for a particular object or system or it can be a property common to many or even all material systems (e.g., energy).
Following Uyemov, we can divide properties into two groups. The properties of the first group constitute “boundaries” of the system or object. With the vanishing of these properties, the system or object changes into something else. These properties are the quality of the system or object. In other words, the quality is an essential property. The properties of the other group constitute no boundary for the object and Uyemov calls them simply properties.18 Thus a physical quantity used to denote a property of a system need not be qualitatively invariant to an essential property, but qualitatively stable.
Our interest in the structure of systems arises from the existence of laws governing the interactions between systems as well as the laws governing the processes taking place within a given system, including the transformation of the structures. Laws express the existence of necessary and essential connections between various aspects of motion of systems (that is, qualitative and quantitative variations and transformations). Laws are thus the expression of the continuing unity of the system in the face of change. Hence, the existence of a stable side of a system is an aspect of the concept of law. It is appropriate to recall Lenin’s characterization of laws as the “enduring (the persisting) in appearances.19 The enduring or persisting phenomena are an expression of the enduring or persisting in the system, since, as we have already indicated, phenomena are manifestations of the properties of a system. The existence of relatively stable aspects of a system provides a basis for the existence of laws, including those laws which express causal relations governing the behavior of the system. To acquire knowledge of a system, “we seek out in the structure of a system the necessary and essential relations. The causally conditioned and structurally determined motion of elements in a system is thereby the basis for the existence of laws.”20
An important step in the search for physical laws is the isolation of a physical system (or group of interacting systems, which then can be considered as a system of higher order). The term essential used in the characterization of structure and law above refers to those relatively stable qualities which give the system a distinctive character during some definite time interval.
These relatively stable physical qualities have a quantitative side to them. When we are able to express this quantitative side numerically, we call these qualities physical quantities. It is unfortunate that the age of mechanism has passed this important concept down to us with this one-sided stress on the quantitative. It is important to note, however, that the attention given to the quantitative was an essential element for the development of the science of mechanics.
It is precisely the qualitative stability occurring in a physical process that provides the basis for the operation of the dialectical law of transformation of quantitative changes into qualitative changes and vice versa. Consider, for example, some amount of water contained in a vessel. The viscosity of the water is a physical quantity which varies with the temperature. As an essential property of water, viscosity is a relatively stable quality which varies qualitatively, but which vanishes altogether when the water freezes. On the other hand, when water freezes, a new physical quantity, hardness, emerges along with a number of other properties associated with the solid state of water, for example, properties of crystals, some of which also change quantitatively with the temperature. The study of the relatively stable or invariant qualitative side of a system and the quantitative changes that can take place without destroying this stability is certainly an important side of scientific research, since a great deal of our interactions with nature is based on the maintenance of stable relationships with nature in one or another aspect. But the hierarchical structure of matter also makes it necessary to investigate the various qualities that emerge from the vast complex of interconnected structures and causal relationships. Engels recognized this when he wrote:
All motion includes mechanical motion, change of place of the largest or smallest portions of matter, and the first task of science, but only the first, is to obtain knowledge of this motion.… The “mechanical” conception . . .explains all change from change of place, all qualitative differences from the quantitative. . . . If all differences and changes of quality are to be reduced to quantitative differences and changes, to mechanical displacement, then we inevitably arrive at the proposition that all matter consists of identical, smallest particles, and that all qualitative differences of the chemical elements of matter are caused by quantitative differences in number and by the spatial grouping of those smallest particles to form atoms.21
Within the past twenty years we have witnessed two major attempts to reduce matter to its ultimate simplest invariant form: the Regge poles in the 1960s and the quarks of today. It is one thing to use these concepts to deepen our insight into the structure of matter, but it is quite another thing to consider them as final solutions, as some are inclined to do.
Within mechanics we find a number of conservation laws: energy, momentum, angular momentum. Conservation laws are encountered in many other branches of physics. The search for invariant quantities can be connected with the vice versa in the dialectical law which Engels referred to as “the law of the transformation of quantity into quality and vice versa.22 For just as the quality of a system remains essentially stable as quantitative changes accumulate, so do certain quantities of the system remain stable as certain qualitative changes occur, that is, as the system itself changes. Laws of quantitative invariance, or conservation laws, constitute an important basis for law-governed transformations of physical matter, since they provide stability to the linkage between different forms of matter in such processes of transformation. While the search for conservation laws is an important side of physical research, the principal task for understanding nature still remains the search for causal links which give rise to the changes resulting from interactions within and between systems.
The achievement of Newton was not that he initiated the effort that led to the discovery of a conservation law in mechanics, but that he found the causality principle of classical mechanics, which was expressed by his first two laws of motion.23 The mechanistic externality of causation implicit in his laws of motion leads to neither conservation of energy, momentum, nor angular momentum. These follow only after isolation of a system of material bodies from external forces. The law of conservation of angular moment m follows only after additional assumptions. The law of conservation of energy was an expression of the transformability of matter in motion from one form to another. It showed us how to utilize thermal energy to perform mechanical work, but the means by which thermal energy is transformable into mechanical work was provided by the kinetic-molecular theory of gases and it could do this in a qualitative way without the law of conservation of energy.
The Atomists of antiquity linked conservation to causality. Thus for Lucretius:
The reason why all mortals are so gripped by fear is that they see all sorts of things happening on the earth and in the sky with no discernible cause, and these they attribute to the will of a god. Accordingly, when we have seen that nothing can be created out of nothing, we shall then have a clearer picture of the path ahead, the problem of how things are created and occasioned without the aid of the gods.24
The indestructible atoms in unceasing motion provided the means of things being created out of other things. Similarly, the existence of a conserved physical quantity in a system means that this quantity does not arise or vanish spontaneously during the transformations that take place within the system, but results from a necessary and essential connection in the process of change. In this sense, the cause of its appearance in the changed state of the system is its occurrence in the old state.
Theobald comments that causality lies at a deeper conceptual level in scientific thinking than conservation, since conservative systems are necessarily causal, but nonconservative systems are not necessarily acausal.25 (In effect, non-Marxist Theobald in 1966, like Engels in 1885, sees the law of conservation of energy as a narrower expression of the transformability of matter.)
Thus the existence of invariances is a necessary condition for the existence of causal relationships, but the invariances themselves do not establish the necessity of a given change.
The Logical and Historical in Scientific Theory
We now turn our attention to the relationship between transformations of material systems and historical processes so that we can consider the claim of Jaeglé and Roubaud that a science of nature must be kept separate from a history of nature.
Let us consider a system that is marked by a high degree of stability, for example, a tank filled with oxygen. When the gas is viewed as a continuous medium, we can establish a quantitative relationship among the pressure, volume, and temperature as physical quantities. They have both quantitative and qualitative characters. One of the qualities of pressure, for example, is that it is directed radially outward from every point inside the volume except at the walls. But this quality has no meaning when we consider the gas from the viewpoint of its molecular structure. In this case, however, we can calculate a “pressure” by imagining a very thin, flat plate of small area suspended somewhere in the volume. We can then calculate the average force resulting from the gas molecules rebounding as they continually strike one side of the plate. If we divide the force by the surface area, we obtain a quantity equal to the pressure. But qualitatively, it is not the same pressure as before. First, the pressure of a gas at every point in a continuous medium is directed radially outward, while the “pressure” calculated from the molecular structure is a force with a unique direction (i.e., perpendicular to the plate whatever the orientation chosen). Second, there is no net force, since it is entirely offset by a similar force from the other side of the plate. The qualitative transition from the molecular level to the level of a continuous medium is therefore effected through a theoretical negation of the discontinuous (discrete) structure into a continuous structure. This theoretical negation does, however, have an objective material basis. Although an ideal gas can be considered as a system of rigid, spherical, noninteracting molecules, real molecules are subject to long- and short-range forces that arise between them. The effects of these forces increase with the concentration of the gas. As a result, the pressure calculated on the basis of a mechanistic model of a gas (rigid spheres of negligibly small but finite diameter interacting only through contact upon collision) becomes less and less accurate. We see, therefore, that the theoretical negation of discreteness corresponds to a material process whereby molecules, which under other conditions can exist as discrete entities, lose this discreteness as they come within the range of intermolecular forces. The negation in theory here reflects an objective negation in the physical world.
We should now consider the relationship of this material basis to historical development,
When we consider a tankful of oxygen, even as a relatively stable form of matter, we are also aware of the complex structure of the gas as a system. For purposes of approximation and analysis, we can consider it as a system made up of a hierarchy of simultaneously existing subsystems, for example, nuclei and electrons, atoms, molecules. An essential difference between the mechanistic and dialectical concepts of systems is that in the mechanistic view the subsystem on each level is considered to have a continuing objective existence (the whole reducible to the sum of its parts), while in the dialectical view, the subsystems lose their individual identities as new qualities emerge that are not present in the subsystems. We have already shown that there is a material basis for the emergence of these new qualities. There is, however, no real “gas in general,” only concrete instances of gas, from which we abstract the general concept of gas. In real life, every concrete form of matter arises from a transformation from other forms. Thus, oxygen nuclei are assumed to have been formed (ultimately) from nuclei of lower mass, and oxygen molecules come into being as a result of the combining of single oxygen atoms, and so on. Thus, the properties of individual samples of gas are a product of the historical process by which the gas was formed and the properties of oxygen gas in general are consequently a product of the generalized historical process. Our scientific knowledge of the properties of the gas is thereby historically conditioned.
Although the logical structure of our theory of a material system is historically conditioned, it does not necessarily follow the historical order. 26 For example, a relatively stable structure has to be studied on the basis of the existing relationships within the systems. Nevertheless, the laws governing the behavior of material systems are the product of historical development to the same extent as the aspects of the system to which the laws pertain are themselves the products of histories development. It is in this sense that dialectical materialists speak of the unity of the logical and the historical.
In the social sciences, we are more conscious of the historical factor. The laws of the earth sciences, insofar as they differ from physics, chemistry, etc., are clearly bound up with the historical existence of the earth. The question becomes more problematical with sciences such as physics and chemistry. All we can say at present that the laws of physics and chemistry appear to have a validity extending over some ten or so billion years. There appears to be ample evidence that the present relatively stable forms of matter such as protons, electrons, chemical atoms, etc., have been present in the observable universe for that period of time. We have no basis, however, to assert their eternal nature.
The process of transformation of matter from the simple to the complex is a historical process that appears to go on throughout the universe. The logical structure of our scientific knowledge of complex structures of matter reflects this historical process in a general way. Krajewski has made an interesting comparison of various ways of establishing a hierarchical order among a number of basic physical, life, and soil sciences. He considered four bases of classification: a) increasing interdependence of one science on another; b) decreasing generalness; c) historical development of nature; d) increasing complexity of the carriers of motion.27 The different bases of classification all led to the same order in which he listed these scientific areas, although some problems arose with the particular branches within those three divisions. If we were to attempt the same for various branches of physics, for example, electromagnetic theory, nuclear physics, atomic and molecular physics, and solid-state physics, we would probably arrange them in that same order for all four bases of classification, which would again indicate the existence of a relationship between the historical and the logical. The relationship, however, cannot be absolutized, since we would run into difficulties trying to insert some other branches of physics, say, mechanics, into the same position on the basis of the four different criteria.
We can conclude that while we do not formulate scientific theory in historical terms, the overall structure of our physical sciences cannot be set in opposition to historical process. This is, however, precisely what Jaeglé and Roubaud do when, for example, they give a section of one of their articles (I) the heading, “For the unique object: art and history. For the recurring object: science.” The generalization of recurring historical process is a process of dialectical negation in which the unique, that is, the concrete, is transferred into the general. The generalization can still have a historical character, for example, the formation of neutron stars. The study of the generalized historical process, as well as the various stages of this process, is the proper subject matter of science, although it does not necessarily take historical form,
Development, Reversibility, Irreversibility, and the Direction of Time
a) Development: The removal of processes of development from the domain of science also leads to difficulties in understanding the physical nature of reversible and irreversible processes. Dialectics deals with the interconnection of things and all aspects of change. Development is not just any movement, but movement as a continuing process of change from the simple to the complex, from lower stages to higher stages. In dialectics the concept of development is expressed through the law of the negation of the negation. [Note added in 2010: The version printed in Revolutionary World included the term “progressive” as an adjective to the word development throughout this paragraph.” It has been omitted here because inclusion of the phrase progressive development would have required a more extensive discussion of the concept of development. See my paper “A Dialectical View of Progressive Development in the Physical World” (Filosofska Mysl, no. 4 : 82–85. In Bulgarian. English version http://www.tc.umn.edu/~marqu002/progdev.htm
b) Reversibility: By reversible processes in the physical sciences we mean something entirely different, namely, a process which would be physically possible if it were to occur in the reverse direction (as in the case of a film running backwards). A swinging pendulum and a collision between two balls on a billiard table are examples of reversible processes if no friction were present. Reversible processes can involve transformations of motion of matter from one form to another—for example, kinetic energy into potential energy, as in the case of a swinging pendulum, or electrical energy into kinetic energy, as in the case of the rotation of a heavy flywheel coupled to the shaft of an electric motor. Our earlier discussion on the dialectics of such processes of transformation applies to these cases, so that reversible processes are also to be looked at dialectically.
Reversible processes, however, are characterized by the absence of a preferential direction of development, since any state of motion can always be restored to its previous state as long as no energy has left the system.
Physics is particularly interested in the nature of reversible processes, since when we look at a film of such a process the laws of physics provide no means for determining whether or not the film is being run in its proper direction. Reversible processes are thus said to be reversible in time, and the question is asked whether there is any physical basis for the direction of time.
The existence of ideally reversible processes in nature has not been established. At best a process can be observed to be reversible only within given limits of accuracy. In macroscopic physics the absence of ideally reversible processes in nature is generally agreed upon. In microscopic physics (on the elementary-particle level) the question is under investigation.
The source of absolute reversibility in a physical theory lies in the intrinsically mechanistic character of its basis. Consider, for example, classical mechanics. The basic causal principle in classical mechanics is contained in Newton’s first and second laws of motion. According to the first law, a body will remain in a state of rest or motion at a constant speed in a given direction except insofar as no external forces are applied to it. Newton’s concept of force was simply that which changed the state of motion of a body. The second law states, among other things, that the direction and magnitude of the change in motion is proportional to the direction and magnitude of the force. Thus if a change from state A to state B occurs as a result of a force F, thus a change from state B back to A is possible if an equal force is applied in the opposite direction. We can tell whether a film of a reversible process is running backward or forward only if we know which force actually occurred when the film was made. How and when the force arose is a question to be settled outside of the basic theory of mechanics. Newton did, of course, investigate gravitational forces, but offered no theory for their origin.
We have already cited Helmholtz’s long-range program for science, namely, the reduction of the phenomena of nature to unchangeable forces. In fact he was very explicit about this:
We have seen above that the phenomena of nature should be reducible to unchangeable ultimate causes.28
In other words, he identified the concept of ultimate causes with those of ultimate forces possessing unchangeable natures.
The classical theory of electromagnetism is founded on almost the same basis. The initial development of the theory of electricity and magnetism was based on electrostatics and magnetostatics—electric and magnetic forces acting as ultimate forces of electrically and magnetically “charged” matter, like Newton’s gravitational forces. The replacement of these static ultimate forces by the electric and magnetic fields of Faraday and Maxwell subsequently moved the theoretical structure away from this Newtonian concept of universal forces.29 The definitions of the fields, however, were still based on the forces with which these fields acted on the bodies carrying the electric and magnetic charges by comparison of their effects with Newton’s laws.
An important break with the traditions of classical mechanics occurred when it was found that the magnetic forces could not each be regarded as ultimate forces in Helmholtz’s sense, but were tied together as interconnected ultimate forces, a change in one giving rise to the appearance of the other. This interconnection was then related back to the field concept based on force. The final form of the theory, as expressed in Maxwell’s famous four equations, showed the same reversible character as mechanics. The reversible nature of the theory is still a shortcoming, since the solutions of Maxwell’s equations show electromagnetic radiation converging on as well as diverging from a moving electric charge. Physicists simply discard as spurious the solution that shows radiation converging on the charged particle.
Despite the mechanistic basis of the force concept in these two basic theories of physics, and the more accurate, but still reversible theories resulting from their relativistic variants, these two basic theories are still of great importance. Although no truly reversible phenomena have been demonstrated to exist, many processes display a high degree of reversibility, and therefore these theories correspond, under a wide range of conditions, to the objective processes of nature within known limits of accuracy.
In this century we have discovered two more “ultimate” forces, known under the names of the strong- (or nuclear) and weak-interaction forces. The theories for these forces are not yet as well developed as in the case of the gravitational and electromagnetic interactions. Ii is not unlikely that additional “forces” will continue to be discovered in time, simply because there are no ultimate forms of matter. A finite number of ultimate forces in nature would correspond to a finite number of ultimate forms of motion of matter in contradiction to the principle of the infinite content of matter,
It appears that reversibility of the laws of physics is a consequence of the exclusion from the domain of physics of questions relating to what forces in fact did arise and the processes by which they arose. If one arbitrarily eliminates actual processes of historical development of the physical world from physics, it should not be surprising that physical processes appear capable of taking any direction. The relative stability of physical laws over a period of what seems to be some ten or so billion years is possibly the reason for the difficulty of embracing the historical within the theoretical framework of physics. The conceptual crisis which we are now facing in connection with the big-bang and similar theories may force us to deal in a more urgent way with this problem. As things now stand, the absence of theoretical generalization of the concrete historical processes of development of physical matter from the domain of physics makes it impossible for the theory to reproduce the concrete behavior of the physical world. [Note added in 2008: There is now intense activity among cosmologists concerning the historical process of the development of physical matter in the wake of the big bang.—E.M.]
c) Irreversibility: Between reversible processes and processes of development, we find another process in physics which we call an irreversible process. An argument could be made that development is an irreversible process, but there is an advantage to using separate terms to discuss certain issues which concern us in the physical sciences. When it is useful to underline the distinction, we will emphasize irreversibility without development by the phrase simple irreversibility.
An example of an irreversible process is the melting of a small piece of ice in a glass of warm water. The spontaneous formation of ice in a glass of warm water would be allowed under the law of conservation of energy if the process were accompanied by an appropriate rise to the temperature of the water. The fact that the process does not take place has been formulated in the law known as the second law of thermodynamics. (The first law is an expression of the conservation of energy.) There are many ways of expressing the second law, but basically it states that the natural tendency of spontaneous physical changes is in the direction from highly ordered forms of motion to less ordered forms. Thus, water organized in the form of compact crystals of ice is a more highly structured form of arrangement of H2O molecules than water in its liquid form. The motion of a real pendulum is an irreversible motion. The mechanical energy of the pendulum is highly structured. Some of the energy will be transformed into thermal energy as a result of friction. Thermal energy is much less structured, consisting largely of vibrational and translational motion in randomly oriented directions. Some of the thermal energy is ultimately radiated into space as electromagnetic waves, again randomly in all directions.
The second law of thermodynamics has been formulated as a law expressing the tendency for the entropy of a system to increase. Entropy is a quantity that can be associated with the number of ways the elements of a system can be arranged without violating the law of conservation of energy. A system built up from highly structured subsystems has lower entropy than a system with elements organized with less structure. The “mobility” of the individual elements of all the separate substructures is limited by the constraints imposed by the degree of internal stability of the substructures of which these elements are a part. If sufficient energy is associated with the internal random motions, there will be a tendency for the substructures to break up. Thus, according to the second law, ice will remain frozen if the energy available from the random motions of the H2O molecules is not sufficient to overcome the bonds fixing relative positions of the molecules in a crystal lattice. If sufficient energy is added to the system in the form of randomized thermal energy, individual molecules will eventually acquire sufficient energy to leave the lattice.
d) Direction of time: It was originally suggested by Boltzmann that the increase of entropy in irreversible processes could serve as a physical basis for the direction of time. An argument against this is given by Schlegel.30 His argument is approximately as follows. Assume we observe two states of entropy. To characterize something as increasing, we already need beforehand a sense of the direction of time. The observed tendency for entropy to increase, which formed the basis for postulating the second law of thermodynamics in terms of entropy, already involved a direction of time obtained from other sources. Therefore the increase in entropy is not a primary definition of the direction of time. Schlegel’s argument, however, does not really establish that irreversible processes cannot be the primary basis for the direction of time, but that the concept of the increase in entropy was not historically the basis for the direction of time. Nevertheless, he has provided a clue to proceeding further with the question.
Schlegel also suggests that there are two essential physical requirements for our time concept: noncyclical processes of change to give us direction and cyclical processes to give a scale for measurement of duration.31 By noncyclical Schlegel means a succession of nonrecurring states; Cyclical processes, however, can be of two types: internally reversible or irreversible. A cyclical process can be represented by the sequence of states corresponding to the numerical sequence 12343212343. . . No direction of time can be obtained from a reversible sequence. An irreversible cyclical process can be represented by the sequence 123412341234. . . A direction of time can be established within each sequence, but no ordering of the cycles as earlier or later is possible. Hence, neither cyclical process can serve for the determination of the direction of time over several cycles.
The suggestion that irreversible processes, or, correspondingly, the increase in entropy, as objectively existing processes in nature (as distinct from theoretical concepts which reflect these processes), can serve as the physical basis for the direction of time does not reflect the principal feature of noncyclical processes in nature, that is, the development of matter from the simple to the complex. In fact, if taken by itself, the increase in entropy and the simple irreversible processes associated with it would appear to give a direction of time in conflict with the evolutionary development of the world of nature, in which the forms of motion of matter go from less order to higher order. Irreversibility and historical development seem to have opposite directions.
A way out of the dilemma is suggested by Prigogene,32 He notes that processes in nature that are marked by simple irreversibility are characteristic of systems that are nearly in equilibrium, that is, systems in which the elements from which they are constituted are nearly uniformly distributed over the states accessible to them. He then suggests that when a system is far from its equilibrium condition, more highly ordered substructures form to facilitate the approach of the system to an equilibrium condition. The formation of these substructures facilitates the transport of available energy from regions in which it was previously concentrated to the new regions that have become available when the constraints are removed. For example, when water in a river flows along almost flat terrain, it flows smoothly. When it flows down a steep terrain, it becomes turbulent. In the latter case, the water forms structures called eddies which can be carried along as a whole. Prigogine’s approach is already being applied to research on biological evolution.33
The framework employed by Prigogene still uses the principle of increase in entropy. While the substructures that are formed represent a localized decrease in entropy (corresponding to the increase in order), the system as a whole is marked by an overall increase in entropy. (The initiation of turbulent flow of water in a pipe increases the loss of energy in the form of heat) Entropy as a whole increases, since the formation of substructures is taking place at the same time that the system as a whole is “spreading out” to occupy the states that have become available to it.
The law of increasing entropy, when based on the concept of states accessible to a system, expresses a statistical tendency, rather than an absolute necessity. The tendency is more likely to be manifested as the number of elements in the system becomes very large. Entropy concepts are thus not seen to be directly applicable to elementary-particle processes, since a limited number of particles are involved at any one time. On the other hand the similarities between the conditions considered by Prigogene are, in some ways, not very much different from those encountered in high-energy particle collisions. The amount of energy available in the collisions is very much greater than the energy that is absorbed in the formation of new structures (new particles), that is, the energy represented by the mass of the particles is usually much less than the energy transported by them once they are formed.
Perhaps the source of the difficulty in extending the concept of formation of structures to processes in elementary-particle collisions lies in the mechanistic character of the statistical basis of the concept of entropy. The starting assumptions are that a system consists of a finite number of unchanging elements that tend to distribute themselves evenly over the states available to them. The motion of the elements thus takes place among states which are also of unchanging character, in the same sense that Newton conceived of the motion of an unchangeable body through a space with properties that were independent of’ the body and its motion.
It is possible that the source of simple irreversibility is the dialectical concepts of universal interconnection and the infinite content of matter. A change arising locally should be able to propagate in an unlimited manner and therefore have an irreversible character. New states become accessible as new structures arise and old states change along with the movement of matter. The causal connections reflected in the existence of conservation laws are associated with the relative stability of the infinite complex of structures and substructures, and become the decisive factors governing the direction of changes in the system, including the emergence of certain new structures and the dissolution of existing ones.
The problem of establishing a physical basis for the direction of time cannot be viewed simply as one of defining a physical quantity. “The basic forms of all being are space and time.”34 Time, like matter and space, is a philosophical category and cannot be defined or postulated on the basis of a single type of physical process. Narski points out that Lenin’s “definition” of matter35 did not postulate the materiality of the world, but the materiality of the world is the result of the generalization of all human practice and the long development of the science of nature and the totality of theoretical thought.36 Our association of the direction of time with the concept of development is likewise the result of the same generalization of human practice and long development of nature and totality of theoretical thought. This source of the direction of time is likely to be a more fruitful starting point for considering the physical basis for entropy changes rather than the other way around.
In this section we have shown that the existence of relatively stable systems and subsystems can account for the success of models in explaining many properties of material systems. This is also the case for fundamental theories based on ultimate forces. The investigation of the transformation of matter in motion and the processes by which the relatively stable structures arise is increasingly becoming the subject of scientific research. We see the investigation of the process of development of material systems as the key to the science of nature. Reversible and irreversible processes have to be examined against the background of the general development of matter.
Dialectical materialism is the theme of the general interconnection and development of matter in motion. Jaeglé and Roubaud see this view of dialectical materialism as a unilateral insistence upon the aspect of change. They propose, instead, a view which should make both permanence and change the subject matter of dialectal materialism. “Permanence and change,” they write, “are two aspects of objective reality, neither of which ever appears without the other” (II).
To Lenin, the most important of the three laws of dialectics is the law of the unity and interpenetration of opposites. It is this law that provides the basis for the inseparable connection between matter and motion, a connection most fundamental to dialectical materialism. “The unity … of opposites is conditional, temporary, transitory, relative. The straggle of mutually exclusive opposites is absolute, just as development and motion are absolute.”37 If permanence and change are two mutually exclusive dialectical opposites having an objective existence in matter, what then is the outcome of the struggle between them in the material world? Using the term stability rather than permanence, we have already seen that stability is subsumed under the concept of law-governed change. Permanence and chain, therefore, cannot be regarded as dialectical opposites objectively occurring in nature.
Jaeglé and Roubaud classify reversibility, recurrence, conservation, and invariance with permanence. Irreversibility and nonrecurrence are grouped with history, that is, with change. They write further:
Knowledge in its most general sense is grasped as the contradictory unity of scientific knowledge, which involves the recurring side of things … and historical knowledge, which involves their nonrecurring aspect. (II)
Since the recurrent was already assigned by them to permanence, there can be no science for things that change. However, objects in the real world change. Therefore the subject matter of science for Jaeglé and Roubaud is not the material world of real objects but the theoretical world of unchanging idealized objects. All knowledge, however, is the reproduction of the objective concrete in the mind. Science is a specific form of this reproduction. The result of science is the conceptual concrete, the systematic sum of abstractions. The objective concrete not a set of unique objects, but a dialectical totality of the unique, the particular, and the general of phenomena and essence, etc.38
Although in their papers Jaeglé and Roubaud consistently fail to recognize that individual historical processes are at the same time universal historical processes (in accordance with the dialectical connection between the individual and the universal) they are correct when they state:
It is because the recurring is present in history in infinitely varied forms that history also has its invariants, conferring upon history the scientific character that renders it intelligible. III)
What they fail to see in their series of papers is that these invariants are not ahistorical, but are the historically conditioned laws of development and transformation of matter, which we not only apply to matter (including its history), but which we also derive from history in correspondence with the historical forms of the material world, even though these historical forms of matter may extend over vast regions of space and time.
In conclusion, I wish to thank the faculty and staff of the Section of Marxist-Leninist Philosophy of Humboldt University in Berlin, German Democratic Republic, for their hospitality during the academic year 1978–79 and the various forms of support given me in this work.
School of Physics and Astronomy
University of Minnesota
l. Pierre Jaeglé and Pierre Roubaud, “Réflexions sur Les Relations entre lea Sciences de la Nature et le Matérialism Dialectique,” Cahiers du Communisme, nos. 7–8 (July–August, 1977), pp., 95–109 (hereafter denoted as I).
2. Pierre Jaeglé and Pierre Roubaud, “Invariance et Dialectique. E1éments de Discussion,” Cahiers du Communisme, no. 11 (November, 1977), pp. 111–15 (hereafter denoted as II).
3. Pierre Jaeglé and Pierre Roubaud, “Science et Histoire,” La Pensée, no. 202 (November–December, 1978), pp. 38–48 (hereafter denoted as III).
4. Frederick Engels, Anti-Dühring (New York: International, 1939), p. 18.
5. Frederick Engels, The Dialectics of Nature (New York: International, 1940), p. 256.
6. Engels, Dialectics of Nature, p. 73.
7. Hermann von Helmholtz, “Über das Ziel and die Fortschritte der Naturwissenschaft,” in Populäre wissenschaftliche Vorträger II (Brunswick: Friedrich Viewag und Sohn, 1871), pp. 190–91.
8, Engels, Dialectics of Nature, pp. 50–51.
9. Karl Popper, “A Realist View of Logic, Physics, and History,” in Physics, Logic, and History, eds. Wolfgang Yourgrau and Allen D. Brick (New York; Plenum. 1970), pp. 6–7.
10. D. W. Theobald, The Concept of Energy (London: Spon, 1966), p. 57.
11. Engels, Dialectics of Nature, p. 72.
12. Ibid., p. 73.
13. Ibid., p. 71.
14. Theobald, p. 176–77.
15. I. V. Blaubcrg, V. N. Sadovsky, and E. G. Yudin, Systems Theory (Moscow: Progress, 1977), pp. 127–32; [Teoriya Sistem (Moscow: Izd. Progress. 1977)].
16. Herbert Hörz, Materialstruktur (Berlin: Deutsch Verlag der Wissenschaften, 1971), p. 89.
17. A. I. Uyomov, Dinge, Eigenschaften and Relationen (Berlin: Academia Verlag, 1965), p. 34. A. I. Uyemov, Veshchi, svoistva i otnosheniye (Moscow: Izd. Akad. Nauk SSSR, 1963).
18. Ibid., p. 35.
18. V. I. Lenin, Philosophical Notebooks, vol. 38 of Collected Works (Moscow: Progress, 1961), p. 151.
20. H. Hörz, H.-D. Pöltz, H. Parthey, U. Röseberg, and K.-F. Wessel, Philosophische Probleme der Physik (Berlin: Deutschcr Verlag der Wissenschaften, 1978), p.45. [note added in 2008: After this article was written, a revised English edition of this book was published under the title Philosophical Problems in Physical Science (Minneapolis: Marxist Educational Press, 1980).
21. Engels, Dialectics of Nature, pp. 320–21.
22. Ibid., p. 26.
23. Erwin Marquit, “Mechanism and the Unity of Matter, Space, and Time in Classical Mechanics,” Revolutionary World 33 (1979), pp. 71–84.
24. Lucretius, The Nature of the Universe, R. E. Latham, trans. (Baltimore: Penguin, 1951), p. 31
25. Theobald, The Concept of Energy, p. 147.
26. Karl Marx, from the Grundrisse manuscripts, in A Contribution to the Critique of Political Economy (London: Lawrence and Wishart, 1971), pp. 205ff.
27. Władysław Krajewski, Engels o ruchu materii i jego prawidłowość (Warsaw: Książka i Wiedza, 1973, pp. 147–61).
28. Helmholtz, Über die Erhaltung der Kraft (Berlin: Reimber, 1847), p. 5.
29. Laszlo Tisza, “The Conceptual Structure of Physics,” Reviews of Modern Physics 35, no. 1 (January, 1963), p. 162.
30. Richard Schlegel, Time and the Physical World (New York: Dover 1968), pp. 16–26.
31. Ibid., chap. 1.
32. I. Prigogene, “Time, Structure and Entropy,” in Time in Science and Philosophy, ed. Jiri Zeman (Prague: Academia, 1971), pp. 89.1 Do,
33. Manfred Eigen, “Self-organization of Matter and the Evolution of Biological Macromolecules,” Naturewissenshaften 58 (1971), pp. 465–523.
34. Engels, Anti-Dühring, p. 60.
35. “Matter is a philosophical category denoting the objective reality which it given to man by his sensations, and which is copied, photographed and reflected by our sensations, while existing independently of them.” Materialism and Empirio-Criticism, vol. 14 of Collected Works (Moscow: Progress, 1962), p.130.
36. I. S. Narski, Dialektischer Widerspruch und Erkenntnislogik (Berlin: Deutscher Velag der Wissenschaften, 1973), p 261. [Dialekticheskoe protivorechie i logika poznaniia (Moscow: Nauka, 1969]
37. Lenin, Philosophical Notebooks, p. 360.
38. I am indebted to András Gedő for drawing my attention to these characteristics of the conceptual concrete and for other helpful comments. I also wish to thank Azaria Polikarov, Ulrich Röseberg, Eftychios Bitsakis, and David DeGrood for their valuable suggestions.