Historical Time

Abstract

This chapter explores the development of the concept and the measurement of time throughout history. Recognition of time philosophically as a “thing” that could be measured and the methods for performing that measurement required several millennia to develop. Measurement has moved from recognizing a consistent daily solar cycle to longer term measures that are synchronized with other celestial events. Shorter measures began as divisions of day and night into what amounted to hours and progressed to smaller and smaller increments to current abilities to measure in units like picoseconds (10⁻¹² seconds). Relativity throws a bit of a monkey wrench into simple time measurement, although the impact is not detailed here. Methods have been and are being developed to account for the effects of relativity on time measurement that will be needed in the future. Interestingly, time is the one measurement that has become fairly standardized throughout the world, regardless of the metric or English systems. The modern standard in the metric SI system is, oddly enough, based on the ancient Mesopotamian method of measurement starting with the second. Attempts to develop a decimal approach to time measurement have not been successful. A number of time measurement units and conversions are provided, along with their historical context.