(b) in the microcosm:

15. Nevertheless, in the face of the undeniable mutability of even inanimate nature, there still rises the enigma of the unexplored microcosm. It seemed, in fact, that, unlike the organic world, inorganic matter was in a certain sense immutable. Its tiniest parts, the chemical atoms, were indeed capable of combining in most diversified manners, but they appeared to be endowed with a privilege of eternal stability and indestructibility, since they emerged unchanged from every chemical synthesis and analysis. A hundred years ago, the elementary particles were still regarded as simple, indivisible, and indestructible.

16. The same idea prevailed regarding the material energy and forces of the cosmos, especially on the basis of the fundamental laws of the conservation of mass and energy. Some natural scientists went so far as to consider themselves authorized to formulate in the name of their science a fantastic monastic philosophy, whose sorry memory is linked up, among others, with the name of Ernst Haeckel. But in the very lifetime of the latter, toward the end of the last century, even this over-simplified conception of the chemical atom was shattered by modern science. The growing knowledge of the periodic system of chemical elements, the discovery of the corpuscular radiations of radio active elements, along with many other similar facts, have demonstrated that the microcosm of the chemical atom, with dimensions as small as ten-millionths of a millimeter, is a theater of continuous mutations, no less than the macrocosm known to all.

In the electronic sphere:

17. It was in the sphere of electronics that the character of mutability was first established. From the electronic structure of the atom there emanate radiations of light and heat which are absorbed by outside bodies, corresponding to the energy level of the electronic orbits. In the exterior parts of this sphere there takes place the ionization of the atom and the transformation of energy in the synthesis and analysis of chemical combinations. At that time, however, it was possible to suppose that these chemico-physical transformations provided one last refuge for stability, since they did not reach the very nucleus of the atom, which is the seat of its mass and of the positive electric charge which determine the place of the chemical atom in the natural system of the elements, and where it seemed science had found, so to speak, an example of an absolutely stable and invariable being.

And in the nucleus:

18. But already at the dawn of the new century, the observation of radioactive processes, which, in their last analysis, were connected with a spontaneous breaking down of the nucleus, began to exclude any such example. Hence, once science had established the fact of instability reaching down into the deepest depths of known nature, there still remained one further perplexing fact, since the atom was apparently unattackable, at least by human forces, because in the beginning all efforts to hasten or to retard its natural radioactive disintegration, or even to break down inactive nuclei, had failed.

19. The first very modest attempt to break down the nucleus (of nitrogen) goes back to hardly more than three decades ago, and it is only in recent years that it has been possible, by bringing into play tremendous forces, to produce very numerous processes involving the formation and the breaking down of nuclei. Although this result-which, insofar as it contributes to the cause of peace, is certainly to be inscribed among the glories of our century-represents in the field of practical nuclear physics no more than a preliminary step, nevertheless, it provides for our consideration an important conclusion, namely, that atomic nuclei are indeed, by many orders of magnitude, more firm and stable than ordinary chemical compositions, but this notwithstanding, they are also, in principle, subject to similar laws of transformation, and hence are mutable.

20. At the same time it was possible to establish that such processes have the greatest importance in the economy of energy of the fixed stars. In the center of our sun, for example, according to Bethe, and in the midst of a temperature which goes as high as some twenty million degrees, there takes place a chain-reaction returning upon itself, in which four hydrogen nuclei combine with one nucleus of helium. The energy thus liberated comes to compensate the loss involved in the radiation of the sun itself.

21. Also, in modern physical laboratories, through bombardment with particles endowed with tremendous energy or with neutrons, successful efforts are being made to effect transformations of nuclei, as can be seen in the example of the atom of uranium. In this connection mention must also be made of the effects of cosmic radiation which can break down even the heaviest atoms, thus not infrequently liberating entire swarms of sub-atomic particles.

22. We have desired to cite only some few examples, but such as could establish beyond all possible doubt the explicit mutability of the inorganic world, large and small: the countless transformations of the forms of energy, especially in the chemical decompositions and combinations taking place in the macrocosm and in no smaller degree, the mutation, a law which is analogous to the law of entropy for the macrocosm. The direction of spontaneous evolution is determined through the diminution of utilizable energy in the structure and the nucleus of the atom, and, up to the present time, science knows of no processes capable of compensating or annulling this exploitation through the spontaneous formation of nuclei having high energy value.