ABSTRACT
All measurement depends on the use of a standard unit. The objective measurement of physical time is therefore an abstraction from lived duration, but because of its greater simplicity. Hence physical time is doubly an abstraction: not only in that it abstracts from the different judgments of duration of individuals, but also in that it abstracts from the irrevocability and irreversibility of time. The abstraction which physics makes from the events which make up the content of time is legitimate and useful for the purposes of physics: but, overridden, it may be fallacious. It cannot be too often emphasized that physics is concerned with the measurement of time, rather than with the essentially metaphysical question as to its nature. For temporal relations, as treated in modern physics, are relational right enough—in their connecting of events lies their utility and importance—but they are scarcely "temporal", except in the specialized sense in which physics uses the word.
