On the meaning of absolute systems in mechanics and physics

Though the word "absolute" in the sense of "not implying any relations" has lost its original meaning, it is still freely used. It is proposed to define an absolute system of reference in the new sense as one which is privileged, because it gives rise to a maximum of simplicity for the expression of the laws of nature. This definition is shown to be in agreement with the practical use of the word. Systems of reference in classical mechanics and systems of units in physics are discussed from this point of view. © 1946 Martinus Nijhoff, The Hague, Holand.