From wristwatches to atomic clocks and NTP time servers, the understanding of time has become crucial for many modern technologies such as satellite navigation and global communications.

From time dilation to the effects of gravity on time, time has many weird and wonderful facets that scientists are only beginning to understand and utilise. Here are some interesting, weird and unusual facts about time:

•    Time is not separate from space, time makes up what Einstein called four dimensional space time. Space time can be warped by gravity meaning that time slows down the greater the gravitational influence.  Thanks to atomic clocks, time on earth can be measured at each subsequent inch above the earth’s surface. That means that every bodies feet are younger than their head as time runs slower the lower to the ground you get.

•    Time is also affected by speed. The only constant in the universe is the speed of light (in a vacuum) which is always the same. Because of Einstein’s famous theories of relativity anybody travelling at close to the speed of light a journey to an observer that would have taken thousands of years would have passed within seconds. This is called time dilation.

•    There is nothing in contemporary physics that prohibits time travel both forward and backwards in time.

•    There are 86400 seconds in a day, 600,000 in a week, more than 2.6 million in a month and more than 31 million in a year. If you live to be 70 years old then you will have lived through over 5.5 billion seconds.

•    A nanosecond is a billionth of a second or roughly the time it takes for light to travel about 1 foot (30 cm).

•    A day is never 24 hours long. The earth’s rotation is speeding up gradually which means the global timescale UTC (coordinated universal time) has to have leap seconds added once or twice a year. These leap seconds are automatically accounted for in any clock synchronization that uses NTP (Network Time Protocol) such as a dedicated NTP time server.

The ‘sat-nav’ has revolutionised the way we travel. From taxi drivers, couriers and the family car to airliners and tanks, satellite navigation devices are now fitted in almost every vehicle as it comes off the production line. While GPS systems certainly have their flaws, they have several uses too. Navigation is just one of the main uses of GPS but it is also employed as a source of time for GPS NTP time servers.

Being able to pin point locations from space has saved countless lives as well as making travelling to unfamiliar destinations trouble free. Satellite navigation relies on a constellation of satellites known as GNSS (Global Navigational Satellite Systems). Currently there is only one fully functioning GNSS in the world which is the Global Positioning System (GPS).

GPS is owned and run by the US military. The satellites broadcast two signals, one for the American military and one for civilian use. Originally, GPS was meant solely for the US armed forces but following an accidental shooting down of an airliner, the then President of the US Ronald Reagan opened the GPS system to the world’s population to prevent future tragedies.

GPS has a constellation of over 30 satellites. At any one time at least four of these satellites are overhead, which is the minimum number required for accurate navigation.

The GPS satellites each have onboard an atomic clock. Atomic clocks use the resonance of an atom (the vibration or frequency at particular energy states) which makes them highly accurate, not losing as much as a second in time over a million years. This incredible precision is what makes satellite navigation possible.

The satellites broadcast a signal from the onboard clock. This signal consists of the time and the position of the satellite. This signal is beamed back to earth where your car’s sat nav retrieves it. By working out how long this signal took to reach the car and triangulating four of these signals the computer in your GPS system will work out exactly where you are on the face of the world.  (Four signals are used because of elevation changes – on a ‘flat’ earth only three would be required).

GPS systems can only work because of the highly precise accuracy of the atomic clocks. Because the signals are broadcast at the speed of light and accuracy of even a millisecond (a thousandth of a second) could alter the positioning calculations by 100 kilometres as light can travel nearly 100,00km each and every second –currently GPS systems are accurate to about five metres.

The atomic clocks onboard GPS systems are not just used for navigation either. Because atomic clocks are so accurate GPS makes a good source of time. NTP time servers use GPS signals to synchronize computers networks to. A NTP GPS server will receive the time signal from the GPS satellite then convert it to UTC (Coordinated Universal Time) and distribute it to all devices on a network providing highly accurate time synchronization.

Measuring the passing of time has been a preoccupation of humans since the dawn of civilization. Broadly speaking, measuring time involves using some form of repetitive cycle to work out how much time has passed. Traditionally this repetitive cycle has been based on the movement of the heavens such as a day being a revolution of the Earth, a month being an entire orbit of the Earth by the moon and a year being earth’s orbit of the sun.

As our technology progressed we have been able to measure time in smaller and smaller increments from sundials that allowed us to count the hours, mechanical clocks that let us monitor the minutes, electronic clocks that let is for the first time accurately record seconds to the current age of atomic clocks where time can be measured to the nanosecond.

With the advancement in chronology that has led to technologies such as NTP clocks, time servers, atomic clocks, GPS satellites and modern global communications, comes with another conundrum: when does a day start and when does it finish.

Most people assume a day is 24 hours long and that it runs from midnight to midnight. However, atomic clocks have revealed to us that a day is not 24 hours and in fact the length of a day varies (and is actually increasing gradually over time).

After atomic clocks were developed there was a call from many sectors to come up with a global timescale. One that uses the ultra precise nature of atomic clocks to measure its passing but also one that takes into account the Earth’s rotation. Failing to account for the variable nature of a day’s length would mean any static timescale would eventually drift with day slowly drifting into night.

To compensate for this the world’s global timescale, called UTC (coordinated universal time) has additional seconds added (leap seconds) to ensure that there is no drift. UTC time is kept true by a constellation of atomic c clocks and it is utilised by modern technologies such as the NTP time server which ensures computer networks all run  the exact same precise time.

Telling the time may seem a simple affair these days with the number of devices that display the time to us and with the incredible accuracy of devices such as atomic clocks and network time servers it is quite easy to see how chronology has been taken for granted.

The nanosecond accuracy that powers technologies such as the GPS system, air traffic control and NTP server systems (Network Time Protocol) is a long way from the first time pieces that were invented and were powered by the movement of the sun across the heavens.

Sun dials were indeed the first real clocks but they obviously did have their downsides - such as not working at night or in cloudy weather, however, being able to tell the time fairly accurately was a complete innovation to civilisation and helped for more structured societies.

However, relying on celestial bodies to keep track of time as we have done for thousands of years, would not prove to be a reliable basis for measuring time as was discovered by the invention of the atomic clock.

Before atomic clocks, electronic clocks provided the highest level of accuracy. These were invented at the turn of the last century and while they were many times more reliable than mechanical clocks they still drifted and would lose a second or two every week.

Electronic clocks worked by using the oscillations (vibrations under energy) of crystals such as quartz, however, atomic clocks use the resonance of individual atoms such as caesium which is such a high number of vibrations per second it makes the incredibly accurate (modern atomic clocks do not drift by even a second every 100 million years).

Once this type of time telling accuracy was discovered it became apparent that our tradition of using the rotation of the earth as a means of telling time was not as accurate as these atomic clocks. Thanks to their accuracy it was soon discovered the Earth’s rotation was not precise and would slow and speed up (by minute amounts) each day. To compensate for this the world’s global timescale UTC (Coordinated Universal Time) has additional seconds added to it once or twice a year (Leap seconds).

Atomic clocks provide the basis of UTC which is used by thousands of NTP servers to synchronise computer networks to.

Chronology – the study of time- has provided science and technology with some incredible innovations and possibilities. From atomic clocks, NTP servers and the GPS system, true and accurate chronology has changed the shape of the world.

Time and the way it is counted has been a preoccupation of mankind since the earliest civilisations. Early chronologists spent their time trying to establish calendars but this proves to be more complicated than first imagined primarily because the earth takes a quarter of a day more than 365 days to orbit the sun.

Establishing the right number of leap days was one of the first challenges and it took several attempts at calendars until the modern Gregorian calendar became adopted by the globe.

When it came to monitoring time at a smaller level great advances were made by Galileo Galilei who would have built the first pendulum clock if only his death hadn’t interrupted his plans. Pendulums were finally invented by Christiaan Huygens and provided the first true glimpse of accurately monitoring the time throughout the day.

The next steps in chronology couldn’t take place though until we had a better understanding of time itself. Newton (Sir Isaac) had the first ideas and had the notion time was absolute” and would flow “equably” for all observers. This would have been an obvious idea to Newton as many of us regard time as unchanging but it was Einstein in his special theory of relativity that proposed that in fact time wasn’t a constant and would differ to all observers.

It was Einstein’s ideas that proved correct and his model of time and space paved the way for many of the modern technologies we take for granted today such as the atomic clock.

However, chronology doesn’t stop there, timekeepers are constantly looking for ways of increasing accuracy with modern atomic clocks so precise they would not lose a second in millions of years.

There are other notable figures in the modern world of chronology too. Professor David Mills from the University of Delaware devised a protocol in the 1980’s to synchronise computer networks.

His Network Time Protocol (NTP) is now used in computer systems and networks all over the world via NTP time servers. A NTP server ensures computers on opposite sides of the globe can run exactly the same time.