present volume is a translation. Eigen means ‘belonging to the self'. Verbatim, Eigenzeit means 'self-time'; Eigenliebe, ‘self-love'. To those who read German, the meaning of eigen in its many combinations is obvious. Because of this obviousness the word Eigenzeit is well suited to imply, in German, a formal linkage between designating temporalities appropriate for the Theory of Relativity (where its precise meaning needs extended explanation) and those appropriate for social science (where its meaning is almost, though not totally, self-evident).
Early in the history of Relativity Theory Eigenzeit was translated into English as Eigen-time, together with such related technical terms as Eigen-function and Eigen-value. Later, the word Eigen was replaced by proper' to yield the names proper time, proper function and proper value. ‘Proper' is a cognate in English of Eigen, as in 'property' (Eigentum) or in the proper days of the saints in the Roman calendar. But while the translation is accurate, the selfevidence of the word and, with it, the hint of some formal kinship between certain physical and social aspects of time are absent. Had Professor Nowotny's book Eigenzeit appeared under the title Proper Time, it would have suggested a work on etiquette for British high tea rather than a treatise on the sociology of time.
What does proper time mean in physics and in this book?
In Relativity Theory it is the time span between two events in the life of a clock as measured by that clock. So far this is only a definition, and not even a very interesting one. It becomes more interesting when one considers two clocks in relative motion, and outright intriguing when the clocks are the biological cycles of living organisms. It is under such conditions that the distinction between time and proper time may be illustrated. Here is an example.
Consider an Indian elephant with its gestation period of 645 days and a house mouse with her 19 days. Let each female mate with her respective male on 1 January. Then, let the mouse go on an extended round trip at very large velocities, with her itinerary designed by a competent relativist. Let her return on 7 October of the next year, just in time to celebrate the simultaneous delivery of the two offsprings. The temporal separation between the twin events (the begetting and delivering of the infants) was 15,480 hours in the elephant's proper time, 456 hours in the proper time of the mouse.
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Foreword