The Need to Measure Time

THE NEED TO MEASURE TIME

One. The need to measure time was felt by human beings a long time ago. In every civilization however ancient, there has been evidence of people keeping track of time. In ancient times, people closely followed the movement of the sun, moon, and the stars. They that once the sun rose in the morning, it would set after a considerable period. They do many things from sunrise to sunset. This gave them a concept of time. People kept track of the passage of time by keeping track of events that were repeated, such as the number of sunrises (days) between two full moons, the number of full moons between two seasons, etc.

As the complexity of their lives increased, people felt the need to split the day into smaller periods. As civilizations grew, more ways of measuring time were devised. Today, we measure time for a variety of applications: we need to meet our clear-cut schedules, the doctor checks how many times our heart beats in one minute, we need to know when a train or plane will arrive, the amount of time a computer will take to perform an operation, and so on. The list is endless.

But how do we define time? The dictionary defines time as the period between two events. For example, sunrise and sunset can be taken as two events. Then the period between sunrise and sunset on a particular day would be the 'time' between the sunrise and sunset.

MEASUREMENT OF TIME

In the beginning, people used calendars to keep a track of years, which were divided into months and days (not exactly what we use today, but something similar). Later, people started keeping track of the time of the day. They started building various instruments to divide the day into smaller parts. An instrument used to measure time is called a clock.

People used instruments such as sundials and hourglass to keep track of time. The movement of the shadow of a rod stuck upright in the ground, whose shadow changed direction with the movement of the sun across the sky, was used to make crude sundials. An hourglass consisted of two rounded glass bulbs connected by a narrow neck of glass. The top bulb was filled with sand and a measured amount of sand particles streamed down from the top bulb into the bottom bulb. The duration taken by sand to stream down from the top bulb into the bottom bulb gave the measure of time. An instrument known as a water clock was also used in different parts of the world. It worked on the principle of regulated flow of water.