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close this bookScience and Technology in the Transformation of the World (UNU, 1982, 496 p.)
close this folderSession I: Science and technology as formative factors of contemporary civilization - from domination to liberation
close this folderScience and the making of contemporary civilization
close this folderJ. Leite Lopes
View the documentIntroduction
View the documentI. The physical image of the world
View the documentII. Science and underdevelopment in Latin America
View the documentIII. Science and dependent development
View the documentIV. Endogenization of science in which society?
View the documentV. The aims of science
View the documentVI. Science for liberation
View the documentNotes

I. The physical image of the world

As is well known, speculations about the structure of the universe were always contained in the cosmogonic models and philosophical systems developed by ancient civilizations.

In Asia, in Africa, in Latin America, superb achievements were obtained by ancient societies - in their mythical approach to the study of nature, in their cultural monuments, in their artistic and technological ingenuity, in their astronomical observations, in the philosophies on space, time, matter, and life that they were led to create and which reflected their forms of interaction with the world

It was, as everyone knows, the atomistic philosophers of ancient Greece who exercised perhaps the greatest influence on the modern conception of the universe.

Before the Greeks, the Babylonians and the Egyptians had already made observations, during many centuries, on the motions of the sun and of the moon with respect to the fixed stars, and knew how to predict lunar and solar eclipses. In spite of the fact that the Greeks identified the celestial bodies with gods, Anexagoras stated that the sun was like a red hot stone and that the moon was made like the earth. The Pythagoreans, at the end of the fifth century B. C., stated that the earth is spherical, Aristarchus of Samos, in the third century B. C., discovered the complete Copernican system, and Eratosthenes, in the year 200 B. C., calculated, according to Claudius Ptolemaeus, the maximum distance of the moon from the earth and the minimum distance between the sun and the earth.

Abu 'All al-Husayn ibn 'Abd Allah ibn Sina, known as Avicenna, philosopher, codifier of Aristotle and one of those who preserved and contributed to the transmission of Greek culture, stated: "Time is the measure of motion.''1 In the Rasa'il, a 51-treatise encyclopedia known as the Koran after the Koran, one finds a list of distances to the planets (as a function of Earth radii) and of sizes of planets; it is stated there that space is "a form abstracted from matter existing only in the consciousness.''] But how many documents were lost or destroyed, as happened for instance in the subjugation of the magnificent pre-Columbian civilizations by the invading Spaniards in Mexico, in Central and South America?

After these systems were forgotten during the decay of later antiquity, there came the Christian medieval model of the image of the world. As expressed in Dante's Paradiso, the earth is the cent re of the universe, Satan is at the centre of the earth, the heavens consist of ten concentric spheres. Everything below the moon is subject to corruption and decay; everything above the moon is indestructible. "God, the Aristotelian Unmoved Mover, causes the rotation of the Primum Mobile, which, in turn, communicates its motion to the sphere of the fixed stars and so on downwards to the sphere of the moon."2

The great scientific revolution in astronomy and in physics came long after the Greeks, in the sixteenth and seventeenth centuries, with the work of Galileo and Newton, who built up the first scientific image of the universe.3 By discovering the laws of motion of the bodies of our daily experience and by generalizing these laws to all bodies in the universe, and by inventing the infinitesimal calculus needed for this work, Newton achieved the first great synthesis, which is the aim of modern science, in intimately correlating ideas and facts apparently strange to one another: the fall of an apple from the tree, the fall of the moon around the earth, the motion of the celestial bodies under the action of universal gravitation. "In the beginning," wrote Einstein in his Autobiographical Notes, "(if there was such a thing) God created Newton's laws of motion together with the necessary masses and forces. This is all; everything beyond this follows from the development of appropriate mathematical methods by means of deduction. What the nineteenth century achieved on the strength of this basis, especially through the application of the partial differential equations, was bound to arouse the admiration of every receptive person."

After the Newtonian mechanics of action at a distance, the notion of field was introduced in physics, mainly through the work of Faraday and Maxwell on electromagnetism, which culminated with another great synthesis, that which unifies the domains of optics, electricity, and magnetism. What made Maxwell's theory "appear revolutionary," wrote again Einstein (reference 4, page 33), "was the transition from forces at a distance to fields as fundamental variables. In this connection I cannot suppress the remark that the Faraday-Maxwell pair has a most remarkable inner similarity with the Galileo-Newton pair - the former of each pair grasping the relations intuitively, and the second one formulating those relations exactly and applying them quantitatively."4

At the end of the nineteenth century, there were the discovery of the electron and of the proton, and a collection of remarkable questions which led, on the one hand, to the discovery of the quantum of action by Planck in 1900 and, on the other hand, to the development of the theory of relativity by Einstein in 1905.

"When one looks back over the development of physics, one sees that it can be pictured as a rather steady development with many small steps and superposed on that a number of big jumps. Of course it is these big jumps which are the most interesting feature of this development. The background of steady development is largely logical, people are working out the ideas which follow from the previous set-up according to standard methods. But then, when we have a big jump, it means that something entirely new has to be introduced. These big jumps usually consist in overcoming a prejudice."5 The inventive physicist finds that he has to question this prejudice and replaces it by an entirely new image of nature.

In his work on the special theory of relativity, Einstein made one of these big jumps and achieved a great new synthesis of apparently disconnected ideas: the prejudice of absolute simultaneity was questioned, analysed, and replaced by a new conception of physical space, a new entity in which ordinary three-dimensional space and time are amalgamated to constitute a four-dimensional manifold, a consequence of which is that space may generate time, energy may generate momentum, energy is equivalent to mass, electric and magnetic fields are aspects of the same subjacent variables, the electromagnetic field.

Moreover, a new concept, that of a superlaw, was introduced by Einstein in physics with his relativity principle. By postulating that the laws of physics must be independent of the state of (rectilinear and uniform) motion of the observer, of its position in space, and of the time at which his observations are made, Einstein formulated a general requirement to be satisfied by the equations of physics. If an ordinary physical law expresses a relationship between variables associated to phenomena and events, the principle of relativity states how such a relationship must be expressed, how it may not be; mathematically, the principle of relativity states, as is well known, that the physical laws must be invariant under a certain group of transformations, the Poincarroup. This was perhaps a striking and very precise realization of the claim, or desire, that scientific knowledge must be wholly impersonal, independent of the physicist who makes the experimental observations. And also the proclamation of absolute statements - the invariant laws - as well as the relativization of the notion of measure, of the values of length, volume, time interval, energy of a physical system, for example, as numbers which depend on the frame of reference in which the measure is carried out.

It was still Einstein - and we commemorate the centennial of his birth this year 1979 - who after ten years of research discovered the relativistic theory of gravitation, one of the most beautiful, if not the most beautiful, constructions in the theoretical physics of all times. By achieving a new synthesis, which generalized Newton's gravitation theory, Einstein identified the gravitational field with the tensor of the space metric, the physical space as described by laws of Riemannian geometry. The machinery of this geometry led Einstein to invent his equation of the gravitational field - an equation which is based on the notion that matter affects the curvature of space-time and that space-time acts back onto matter and determines the nature of its motion: a revolutionary concept which destroys the old notion of space as a passive stage where events take place, without affecting them, as proclaimed by Leibnitz.6

It was mainly his invention of the relativistic theory of gravitation which led Einstein to formulate his conception of the genesis of scientific knowledge in physics: the concepts and the laws which relate them to one another can be discovered by means of purely mathematical constructions, and give the key to the understanding of natural phenomena. Experience may suggest the appropriate mathematical ideas but these can surely not be deduced from it. Experience, of course, remains as the only valid criterion for judging the physical utility of a mathematical theory. But "the concepts and principles are free inventions of the human intellect, which cannot be justified either by nature of that intellect or in any other fashion a priori."7

This epistemological conception of scientific work, of, so to say, an anti-Baconian character, is indeed to be found from Newton, Lagrange, Hamilton, to Einstein, De Broglie, Heisenberg, and Dirac.

The discovery and the development of the theory which describes atomic phenomena - quantum mechanics - as well as research on the ultimate constituents of matter, the so-called elementary particles, dominated the physics of the last fifty years.

It was only in the beginning of the eighteenth century that the atomic hypothesis, put forward by the Greek philosophers, lost its theological and metaphysical character. Democritus, in the fourth century B. C., stated that "the only existing things are atoms and the vacuum; all else is mere opinion"; and thereby put forward the important notion that the complex variety of bodies and phenomena result from the motions and interactions between invisible and indivisible particles, the atoms, which obey "simple" laws. Newton himself wrote: "It seems probable to me that God in the Beginning formed matter in solid, messy, hard, impenetrable, moveable Particles of such Sizes and Figures and with such other Properties and in such Proportion to Space as most conduced to the End for which he formed them; and that these primitive Particles being Solids, are incomparably harder than any porous Bodies compounded of them; even so very hard, as never to wear out or break in pieces; no ordinary Power being able to divide what God himself made one in the first Creation."8

You all know that the atoms - or at least the objects we came to call atoms - were found to be rather complex systems. The development of modern science, from the seventeenth century to our days, the extraordinary achievements of experimental techniques and ingenuity' the birth and development of scientific thought, led to the replacement of the metaphysical approach to natural philosophy by the rational approach based on experimental evidence, on mathematical models constructed on the results of observations and on inventive intuition.

The notion of an indivisible atom gave place to the concept of elementary particles and one hoped that these particles would be - in small number - the fundamental constituents of matter. In the last decades, however, a large number of such sub-atomic particles were discovered, a number which is now in competition with the hundred atoms or so which integrate Mendelejev's periodic table. We now know six species of leptons, particles which include - and have properties in common with - the electron and its neutrino. There are the baryons, particles related to protons and neutrons; the mesons, which are. exchanged between baryons; there is the photon, the particle of light, responsible for the propagation of electromagnetic forces. We assume the existence of particles which have not yet been observed such as the graviton, which propagates gravity, the weak mesons, which propagate weak interactions. The mathematical beauty of the present attempts to unify the weak, strong, and electromagnetic forces, such as the Salam-Weinberg model, lead most of the present-day physicists to believe in the existence of the latter particles. This unification, in which are concentrated the efforts of the physicists who specialize in the domain of high-energy physics, will constitute a great new synthesis, comparable to those which were mentioned earlier in this paper.

And this is the present hope: to reduce the different forms of observed forces, the gravitational interactions, the weak interactions, the electromagnetic forces, and the strong forces (responsible for the existence of nuclei and therefore of matter) to different manifestations of certain underlying basic entities called gauge fields.

This unification is an old dream which started with the attempts of Einstein to include the electromagnetic forces in the unification of gravitation and space-time geometry. And it is the method introduced with so much force and elegance by Einstein in theoretical physics, the search for symmetry groups which leave invariant basic physical laws which is at the root of our present-day work.

Matter, on the other hand, the variety of elementary particles mentioned above, seems to be constituted - with the probable exception of the leptons - by certain objects called quarks. The quarks would be the latest elements in the fragmentation scalation of matter, ultimate particles which integrate the heavy elementary particles but which would be, for some reason not yet fully understood, not observed as free particles. Quarks would most probably be confined inside the elementary particles and this notion would perhaps give the key for us to stop in the process of reduction of matter to smaller and smaller constituents

To conclude this picture of our physical image of the world, let me say just a few words on the astrophysicist's conception of the universe.

It was after the discovery of the relativistic theory of gravitation that cosmology started to develop as a science. From 1917 observational data and theoretical studies laid the foundations of this discipline which has not stopped developing since.

As stated by a distinguished cosmologist, "the existence of the universe is clearly its most important characteristic but I am referring here to the stronger idea that it is meaningful to talk of the universe as a whole, as a single well-defined concept. This idea is one of the most important, perhaps the most important, scientific discovery of the twentieth century." That the universe is unique, and that we can apply to its study the physical laws which are locally established, are postulates generally admitted. Observations of stars and galaxies and objects revealed by the emission of invisible radio waves have led the astrophysicists to the conception that the whole universe is in a state of expansion, of continuous change with time. The notion of expansion of the universe was the result of observations of the red shifts of the galaxies, radio source counts, abundance of the elements. The extrapolation into the past of this outward movement of galaxies, the discovery of the background microwave radiation, have led to the conclusion that our world came into existence in a sudden way, out of an explosion, a "big bang." This is the so-called "standard hot big bang model" according to which, at the beginning, about 15 billion years ago, elementary particles were highly concentrated and under thermodynamic equilibrium at extremely high temperature, with the decay of particles and recombination of pairs in the first few seconds. With the motion of these particles the temperature dropped and there occurred the formation of elements, with the production of helium out of protons and neutrons. Later on heavier elements were produced out of nuclear reactions and the stars became intensely hot furnaces in which ordinary matter was forged out of protons.

And thus we are still left with the question of what happened before the initial state of nearly infinite density and temperature and pressure. Other models of the universe are also investigated by cosmologists who attack fascinating questions such as the possible permanent expansion of the universe or its return to contraction, the gravitational collapse, the existence of singularities in nature.

Such is the evolution of our ideas about the universe, from the old civilizations to present days. It is fascinating to learn that the matter of our localized world, "the carbon and nitrogen of our bodies, the oxygen we breathe, the iron in our blood were all generated inside stellar furnaces at remote epochs in the past.''10 And that in any case, as dreamed of by Anaxagoras, in the times of Pericles, the sun is like a red-hot stone and the moon is made of earth.