The Birth of Modern Time
Whilst the passing of time predates humanity, the way we view it has certainly not remained constant. As systems of counting and measurement evolved, along with our ability to comprehend and discuss the hypothetical, our relationship with time has changed dramatically. The popular twentieth century model views Time as the fourth dimension; something we move within as within the first three. However, there are obvious flaws in this theory - we cannot move through time at will – and it remains one of the real mysteries of modern physics, much discussed yet little understood.
It is impossible to say exactly when humans first began to measure time, but evidence from Ancient Egypt shows that obelisks were being used to judge the time from the sun over 5000 years ago. As societies began to rely on agriculture, it became more important to be able to predict the pattern of the seasons; the passing of time became a subject of great interest. Calendars were developed, and scholars dedicated themselves to studying the stars in order to equate the lunar and solar calendars.
Developing systems of measuring time and season gave early human civilizations great advantages. The measurement of time was a key factor in enabling societies to develop from small hunter-gatherer tribes into larger social groups. By predicting patterns of daylight and weather, and measuring intervals in order to perform tasks regularly, people were able to cultivate land on a larger scale. This in turn left more free time for examining abstract questions such as the passing of time.
Whilst these are obvious immediate benefits to be found by measuring time, it was religious teaching that compelled the most speculation on the nature of time for early civilizations. Islam, Judaism, and early Christianity all inspired the development of methods of timekeeping, due to the need to organise daily worship.
A good example of this is provided by one of the later systems, the "canonical hours" of the early Christian church. Eight time periods are distinguished to mark the intervals between standard prayers: Psalm 119:164 states that "Seven times a day I praise you for your righteous laws". Islamic societies developed "Astrolabes", some of the earliest clocks, in order to organise the five daily ritual prayers, and many Islamic cities still structure the day around these sessions, which are announced publicly.
Religious ideas and methods of measuring earthly time do not always sit very easily together, due to the conflict between an omniscient God, who exists outside of time and is not governed by it as we are, and the linear time experienced on earth. Trying to impose a system of measurement on a cycle created by God has been criticised as heresy by a wide range of religions through the ages. To use a modern example, when the government of Iran, an Islamic country, introduced a method of daylight savings time in 1996 it was the subject of much controversy as it was seen as a Government attempt to interfere with the pattern of things ordained by God.
Our conception of time has evolved as our methods of measuring it have become more precise. It is thought that for early cultures, beyond hours time units would just have been grouped as "a short time". Early time pieces such as sundials and water clocks, and then later early mechanical clocks, generally only had one hand; the focus was on counting hours; smaller time measurements were unimportant. As cultures became accustomed to the mechanisms available, we became more dependent on timing things accurately. It seems perfectly natural to us now to schedule a meeting to the minute, but just a few hundred years ago this would have been regarded as a ridiculous, if not a meaningless, idea.
The modern convention of dividing a day into twelve hours (and a full day and night into twenty four) is thought to originate as far back as Ancient Egypt, and was developed further by the Greek and Roman civilizations. The reason for choosing twelve increments probably relates to the fact that it is the number of lunar months in a year. Before the hour was assigned a standard duration, it was generally taken as a twelfth of the duration of daylight on any particular day – starting from sunrise and ending at sunset. This meant that the length of an hour varied with the seasons, getting shorter in winter and longer in the summer, and also in different locations around the world.
A standard "isochronous" hour, taking up a specific interval, was not developed until 1656, when Christiaan Huygaans invented the pendulum clock. As a result, the modern system was adopted, in which the number of hours of daylight vary rather than the length of the units. However, clocks in different parts of the world would still be co-ordinated with the sun at noon in that particular area, with the result that time varied between regions. It was not until the development of the train system that it became necessary for clocks to be synchronized across a larger area or country.
Modern accurate methods of time measurement enable us to conduct global trading and fly internationally, as well as predict the time on the clocks in any given part of the world. However, the nature of time is a topic which still fascinates physicists and philosophers.