Keeping track of time has been as integral part of helping human civilisation to develop. It could be argued that the greatest step that mankind took was in the development of farming, allowing humans to free up more time to develop sophisticated cultures.
However, farming was fundamentally reliant on timekeeping. Crops are seasonal and knowing when to plant them is the key to all horticulture. It is believed that ancient monuments such as Stonehenge were elaborate calendars helping the ancients to identify the shortest and longest days (solstice).
As human civilisation developed, telling increasingly accurate time became more and more important. And identifying days of the year was one thing but calculating how far into a day was another.
Timing was extremely inaccurate up until the middle ages. People would rely on comparisons of time as a time reference such as how long it took to walk a mile or the time of day would be estimated from when the sun was highest (noon).
Fortunately the development of clocks during the middle of the last millennium meant that for the first time humans could tell with some degree of precision the time of day. As clocks developed so did their accuracy and civilisation became more efficient as events could be more accurately synchronised.
When electronic clocks arrived at the turn of the last century, accuracy was further increased and new technologies started to develop but it wasn’t until the rise of the atomic clock that the modern world really took shape.
Atomic clocks have enabled technologies such as satellites, computer networks and GPS tracking possible as they are so accurate – to within a second every hundred million years.
The atomic clocks were even discovered to be even more accurate than the spin of the Earth that varies, thanks to the Moon’s gravity and extra seconds have to be added to the length of a day – The leap second.
Atomic clocks mean that a global timescale accurate to within a thousandth of second has been developed called UTC – Coordinated Universal Time.
Computer networks to communicate with each other from across the globe in perfect synchronisation to UTC if they use a NTP time server.
An NTP server will synchronise an entire computer network to within a few milliseconds of UTC time allowing global communications and transactions.
Atomic clocks are still being developed the latest strontium clocks are promising accuracy to within a second every billion years.