Einstein by Philipp Frank Page A

of body is filled with, the plain truth is that he [Newton] believes God to be omnipresent in the literal sense; and that as we are sensible of objects when their images are brought home within the brain, so God must be sensible of everything, being intimately present with everything: for he [Newton] supposes that as Godis present in space where there is no body, he is present in space when a body is also present.”
    E. A. Burtt in
The Metaphysical Foundations of Modern Physical Science
, published in 1925, interprets correctly:
    “Certainly, at least, God must know whether any given motion is absolute or relative. The divine consciousness furnishes the ultimate center of reference for absolute motion. Moreover, the animism in Newton’s conception of force plays a part in the premise of the position. God is the ultimate originator of motion. Thus in the last analysis all relative or absolute motion is the resultant of an expenditure of the divine energy. Whenever the divine intelligence is cognizant of such an expenditure, the motion so added to the system of the world must be absolute.”
    By means of this anthropomorphic conception of God, a scientific, almost physical definition of absolute motion is obtained. It is linked with the energy expended by a being called “God,” but to which properties of a physical system are ascribed. Otherwise the concept of energy could not be applied to the system. Fundamentally the definition means that one assumes the existence in the world of a real source of energy that is distinguished from all others. Motion produced by the energy expenditure of mechanical systems in general is described as only “relative” motion, while motion produced by this select being is characterized as “absolute.” It should never be forgotten, however, that the logical admissibility of this definition of absolute motion is bound up with the existence of the energy-producing being. During the eighteenth century, in the age of the Enlightenment, men no longer liked to ascribe to God a part in the laws of physics. But it was forgotten that Newton’s concept of “absolute motion” was thereby deprived of any content. Burtt in his aforementioned book says very aptly: “When, in the eighteenth century, Newton’s conception of the world was gradually shorn of its religious relations, the ultimate justification for absolute space and time as he had portrayed them disappeared and the entities were left empty.”
     
7.
Critics of the Mechanistic Philosophy
    Toward the end of the nineteenth century more and more physical phenomena were discovered that could be explained only with great difficulty and in a very involved wayby the principles of Newtonian mechanics. As a consequence new thories appeared in which it was not clear whether they could be derived from Newtonian mechanics, but which were accepted as temporary representations of the observed phenomena. Was this true knowledge of nature or only a “mathematical description,” as the Copernican system was considered in medieval physics? These doubts could not be resolved so long as it was believed that there were philosophical proofs according to which reduction to Newtonian mechanics provided the only possibility for the true understanding of nature.
    During the last quarter of the nineteenth century a critical attitude toward this mechanistic philosophy became more and more evident. An understanding of this criticism is an essential prerequisite for the understanding of Einstein’s theory and its position in the development of our knowledge of nature. As long as it was believed that Newtonian mechanics was based ultimately on human reason and could not be shaken by scientific advance, every attempt such as that of Einstein, to establish a theory of motion not founded on Newton’s theory necessarily appeared absurd. The critics of mechanistic philosophy plowed the soil in which Einstein was then able to plant his seeds.
    As the first of these