The Writings of Charles De Koninck: Volume 1

Epistemology and Metaphysics

section one Epistemology and Metaphysics Let us review the chief original contributions of Eddington to science in the experimental domain as well as in the domain of theory. This will enable us better to situate his personality. For it must be acknowledged that Eddington is above all a physicist who does philosophy only on the side—“a little,”in his estimation! His competence in the scientific domain make his extra-scientific speculations all the more interesting in that he is capable of envisaging these problems from within physics. His assertion that we must go beyond physics is therefore all the more grounded.We cannot overlook this point. He is, very exceptionally,a great physicist and a great philosopher.These two qualities are inseparably united in his very personality, and we would distort it if we neglected either the one or the other. I. The Double Stellar Current [Le double courant stellaire] It was in 1906 that he attracted the attention of the astronomical world on the occasion of his first presentation to the Royal Society, entitled“The Systematic Motions of the Stars.”4 In this study he takes up a hypothesis advanced by the celebrated Dutch astronomer Kapteyn in 1904, an hypothesis which held that the movements of the ensemble of stars is not fortuitous, as the current opinion would have it, but that there are two favored movements . Until then, this hypothesis had had no success. Here Eddington already displays “the feeling of being on the right path before any proof,” of which he often speaks.5 He allows himself to be first guided by the aesthetic appearance of a theory. This is how this problem should be situated. Since the time of Herschel the hypothesis has been suggested that the galactic system has the form of an extra-galactic nebula. This hypothesis extends only to the static form of the system. The known movements were considered to be proper to each  star taken individually, whereas the movements of the whole were fortuitous. It was then that Kapteyn showed that the stars seemed to follow two opposed directions in the galactic plan: the movement of stars in the neighborhood of the sun would follow two opposed courses: there are two systems, one in a movement opposed to the other. Eddington wanted to verify this hypothesis by an independent investigation . The rotary movement of the nebula was known. The demonstration of this hypothesis would show that the galactic system is itself a dynamic system, just like the extra-galactic nebula. This demonstration would provide a point of reference for new studies of the origin of this system and of its situation in the whole universe. His investigation took from eight to nine years. In 1914, we find these results synthesized in a volume titled Stellar Movements and the Structure of the Universe. The conclusion was affirmative. It was based first of all on a minute analysis of the Catalogue of Professor Boss which gave the proper movements of about six thousand stars. Applying the statistical method, Eddington showed that it is necessary to divide them into two systems. He found a second confirmation of the hypothesis of Kapteyn in the spectroscopic speed of stars. By this quantitative demonstration of the Hollendale hypothesis, the name of Eddington would remain associated with this branch of sidereal astronomy. This work taken in its entirety marked, according to the expression of de Sitter, an advance in the history of astronomy.6 II. The Internal Constitution of Stars The first attempt to classify stars according to their spectra was made by the Italian Jesuit Secchi (1818‒ ‒1878). He divided the life of a star into four stages which marked a greater and greater decrease of temperature. Then Lane (in 1878) showed that when a gaseous body contracts in losing heat, its temperature increases. It was therefore equally possible that stars having a reddish [rougentre] spectrum, and thus belonging to a lower stage, increased in temperature while losing heat. Therefore they could be, contrary to the view of Secchi, in their youth. In 1913 H.N. Russell and E. Hertzsprung showed that it was necessary to place stars in two categories: giants and dwarfs. The first  | Charles De Koninck are of great size, but of weak density, whereas the second are shrunk, more dense, and losing temperature. Thus each star passes twice through the same degree of temperature. Eddington’s...