Life and death

by A. Dastre

Origin of the Idea of Energy.—A new term, namely energy, has been for some years introduced into natural science, and has ever since assumed a more and more important place. It is owing to the English physicists, and especially to the English electrical engineers, that this expression has made its way into technology, an expression which is part and parcel of both languages, and which has the same meaning in both. The idea it expresses is, in fact, of infinite value in industrial applications, and that is why its use has gradually spread and become generalized. But it is not merely a practical idea. It is above all a theoretical idea of capital importance to pure theory. It has become the point of departure of a science, energetics, which, although born but yesterday, already claims to embrace, co-ordinate, and blend within itself all the other sciences of physical and living nature, which the imperfection of our knowledge alone had hitherto kept distinct and apart.

On the threshold of this new science we find inscribed the principle of the conservation of energy, which has been presented to us by some as Nature’s supreme law, and which we may say dominates natural philosophy. Its discovery marked a new era and accomplished a profound revolution in our conception of the universe. It is due to a doctor, Robert Mayer, who practised in a little town in Wurtemberg, and who formulated the new principle in 1842, and afterwards developed its consequences in a series of publications between 1845 and 1851. They remained almost unknown until Helmholtz, in his celebrated memoir on the conservation of force, brought them to light and gave them the importance they deserved. From that time forward the name of the doctor of Heilbronn, until then obscure, has taken its place among the most honoured names in the history of science.[5]

As for energetics, of which thermodynamics is only a section, it is agreed that even if it cannot forthwith absorb mechanics, astronomy, physics, chemistry, and physiology, and build up that general science which will be in the future the one and only science of nature, it furnishes a preparation for that ideal state, and is a first step in the ascent to definite progress.

Here I propose to expound these new ideas, in so far as they contain anything universally accessible; and in the second place, I propose to show their application to physiology—that is to say, to point out their rôle and their influence in the phenomena of life.

Postulate: the Phenomena of Nature bring into play only two Elements, Matter and Energy.—If we try to account for the phenomena of the universe, we must admit with most physicists that they bring into play two elements, and two elements only; namely, matter and energy. All manifestations are exhibited in one or other of these two forms. This, we may say, is the postulate of experimental science.

Just as gold, lead, oxygen, the metalloids, and the metals are different kinds of matter, so it has been recognized that sound, light, heat, and generally, the imponderable agents of the days of early physics, are different varieties of energy. The first of these ideas is older and more familiar to us, but it has not for that reason a more certain existence. Energy is objective reality for the same reason that matter is. The latter certainly appears more tangible and more easily grasped by the senses. But, upon reflection, we are assured that the best proof of their existence, in both cases, is given by the law of their conservation—that is to say, their persistence in subsisting.

The objective existence of matter and that of energy will therefore be taken here as a postulate of physical science. Metaphysicians may discuss them. We have but little room for such a discussion.

§ I. Matter.

It is certainly difficult to give a definition of matter which will satisfy both physicists and metaphysicians.

Mechanical Explanation of the Universe. Matter is Mass.—Physicists have a tendency to consider all natural phenomena from the point of view of mechanics. They believe that there is a mechanical explanation of the universe. They are always on the look out for it, implicitly or explicitly. They endeavour to reduce each category of physical facts to the type of the facts of mechanics. They have made up their minds to see nowhere anything but the play of motion and force. Astronomy is celestial mechanics. Acoustics is the mechanics of the vibratory movements of the air or of sonorous bodies. Physical optics has become the mechanics of the undulations of the ether, after having been the mechanics of emission—a wonderful mechanics which represents exactly all the phenomena of light, and furnishes us with a perfect objective image of it. Heat, in its turn, has been reduced to a mode of motion, and thermodynamics claims to embrace all its manifestations. As early as 1812, Sir Humphry Davy wrote as follows:—“The immediate cause of heat is motion, and the laws of transmission are precisely the same as those of the transmission of motion.” From that time forth, this conception developed into what is really a science. The constitution of gases has been conceived by means of two elements—particles, and the motions of these particles, determined in the strictest detail. And finally, in spite of the difficulties of the representation of electrical and magnetic phenomena after Ampère and before Maxwell and Hertz, physicists have been able to announce in the second half of the nineteenth century the unity of the physical forces realized in and by mechanics. From that time forth, all phenomena have been conceived as motion or modes of motion, only differing essentially one from the other in so far as motions may differ—that is to say, in the masses of the moving particles, their velocities, and their trajectories. The external world has appeared essentially homogeneous; it has fallen a prize to mechanics. Above all, there is heterogeneity in ourselves. It is in the brain, which responds to the nervous influx engendered by the longitudinal vibration of the air, by the specific sensation of sound, which responds to the transverse vibration of the ether by a luminous sensation, and in general to each form of motion by an irreducible specific sensation.