Methods of keeping track of time have altered throughout history with ever increasing accuracy has being the catalyst for change.
Most methods of timekeeping have traditionally been based on the movement of the Earth around the Sun. For millennia, a day has been divided into 24 equal parts that have become known as hours. Basing our timescales on the rotation of the Earth has been adequate for most of our historical needs, however as technology advances, the need for an ever increasingly accurate timescale has been evident.
The problem with the traditional methods became apparent when the first truly accurate timepieces – the atomic clock was developed in the 1950’s. Because these timepieces was based on the frequency of atoms and were accurate to within a second every million years it was soon discovered that our day, that we had always presumed as being precisely 24 hours, altered from day to day.
The affects of the Moon’s gravity on our oceans causes the Earth to slow and speed up during its rotation – some days are longer than 24 hours whilst others are shorter. Whilst this minute differences in the length of a day have made little difference to our daily lives it this inaccuracy has implications for many of our modern technologies such as satellite communication and global positioning.
A timescale has been developed to deal with the inaccuracies in the Earth’s spin – Coordinated Universal Time (UTC). It is based on the traditional 24-hour Earth rotation known as Greenwich Meantime (GMT) but accounts for the inaccuracies in the earth’s spin by having so-called ‘Leap Seconds’ added (or subtracted).
As UTC is based on the time told by atomic clocks it is incredibly accurate and therefore has been adopted as the World’s civilian timescale and is used by business and commerce all over the globe.
Most computer networks can be synchronised to UTC by using a dedicated NTP time server.