What the Units of Time Stand For
Physicists point out that time is a physical quantity and it is, in fact, a dimension of the physical world and, thus, must be measurable and, thus, there is the need for the unit of time. On the other hand, philosophers debate that time is just a product of complex mind and is relative to each unique mind.
The units of time that we will be referring to are the ones that science defines.
Who, What and When
In the advent of civilization, the units of time were not as defined as they are today. In ancient times, time was noted only as a matter of day and night. Some tribes and civilization might include dawn, daybreak, noon, and sundown. But commonly, most prehistoric individuals define time in reference to the natural lighting conditions.
There are also some early tribes who measures time with the actions of plants and animal in their surroundings, so it is not unusual to observe that their units of time would be named like “when the roster crows,” “when the wolf howls,” and “when the cricket sings.”
It is fascinating though that the present system used to define the units of time dates back to the early 2000 BC from the Sumerian civilization. (The Sumerian civilization emerged upon the flood plain of the lower areas of the Tigris and Euphrates Rivers in about 4000 B.C.). The Sexagesinal system, which defines the 60 second per minute and 60 minute per hour, was the product of this civilization.
Other civilizations like the early Egyptians and Greeks only use the hour as their unit of time. This is further proven by the use of the sundial, the hour glass and the water clock.
The Present of Time Keeping
While the present units of time were based on the Sumerian’s Sexagesimal system, the definition of each units of time has been made more accurate. Currently, one second is equated to the length of time that Caesium 133 completes 9,192,631,770 radiation periods. This approximation has been the most accurate as far as time measurement is concerned.
The second is then further divided through the use of the SI system of measure. The smallest measurable unit of a second is the nanosecond, which is equal to a billionth of the said unit. The other units of time like the minute, the hour, the day, the month, and the year are not included in the SI standardization and still follows the Sexagesimal system.
Filed under: Time keeping, Units of time | Tagged: time measurement, unit of time, Units of time
