History of Time Keeping, Calendars, Clocks and NTP Servers

Time has always been a fascination for mankind although it has only been recently, thanks to the work of Albert Einstein and others, have we have begun to understand exactly what it is.However, despite our lack of understanding, people have been preoccupied with measuring the passing of time.Traditionally, due to concepts such as farming and religion, the measurement of time has always been based on the movement of the Earth around the Sun, understandably as the planting and growing of crops is seasonal. Also the movement of the moon has been used to measure the passing of time which has traditionally meant our calendars have been divided by the number of days the Earth goes around the Sun (365) and how long it takes the moon to circle the Earth (28).However our calendars have always faced a fundamental problem in that the moons orbit or 28 days can be divided by seven days of a week, seven doesn’t go into 365. Furthermore the Earth takes six hours more than just 365 days to circle the sun.This caused tremendous problems in the early days of calendars as the Roman, Julian Calendar did not  account for enough leap years and farmers soon found themselves unsure of the correct day to plant crops (as summer was slowly becoming winter and vice versa).Fortunately the Gregorian calendar replaced the Roman calendar and the number of leap years increased to keep the seasons in line with the calendar.The main use of calendars was to keep track of events such as harvest and religious festivals however when it came to day-to-day timekeeping accuracy didn’t start until the development of the clock in the middle-ages.Clocks meant for the first time people could know exactly what time of day it was and would no longer have to trust observations and comparisons to measure daily time such as ‘the time it takes to walk a mile’ or ‘when the sun is at its highest. Timescales were also introduced allowing the hours in the day to be aligned with the movement of the Sun so noon would be the day’s zenith.Following mechanical clocks, electronic clocks soon became favoured as they were far more accurate but it wasn’t until the development of atomic clocks in the 1950’s that true accuracy became possible.After the atomic clock, that are accurate to within a second every million years, it was discovered that the Earth itself is not a reliable time source. The Earth slows in its axis, albeit minutely, but if nothing was done to compensate eventually in a several millennia a day would become night and vice versa.A new timescale called UTC (Coordinated Universal Time) was developed to compensate for this, it was based on the time told by atomic clocks but compensated for the slowing of the Earth by adding Leap Seconds every year or so.Atomic clocks and UTC have meant that technologies, such as the Internet and satellite communication have now become possible. Now computers all over the world can communicate with each other using NTP servers (Network Time Protocol). NTP servers ensure the whole world uses the same timescale and means computer networks can communicate successfully all over the world.