In our 24-hour society, the accurate tracking of time now impacts on every facet of our lives. Time is everywhere from our bedside tables to the computers we use for work and leisure. With clocks that only lose milliseconds over centuries, you would think that time is now well understood.
However, the study of time still holds a strong fascination with scientists and amateurs alike as they continue to search for an even more accurate way of tracking it. If you thought time was little more than a commodity that seems to slip through your fingers, read on to discover what time is, how we measure its passage, and how you can make sure you never miss a second.
Time is a genie that we have managed to successfully tame, but it can still amaze and astonish us. Scientists and amateurs alike continue to investigate time and attempt to develop even more accurate ways of measuring it to give the electronic systems we rely on more versatility and much more reliability.
There is no single global timepiece that all other clocks are set by. It's a myth that the atomic clock at Greenwich is used to set all other clocks. The reality is that around 40 labs across the world maintain 260 atomic clocks that all help to accurately track the world's various time zones.
In the UK, the National Physical Laboratory is responsible for accurate timekeeping. Since 2007, the Anthorn Radio Station has broadcast the time from the NPL's atomic clock across the UK to radio controlled clocks and watches, and the speaking clock.
The accurate tracking of time is an essential component of our lives. Without an agreed global time scale, human society simply couldn't function. You have to go back to 1884 at the Royal Observatory Greenwich astronomy to find the first recorded instance of international time.
The International Meridian Conference held that year decided that Greenwich would be used as the Prime Meridian that all other time zones would extrapolate from. Today, Greenwich Mean Time should be properly known as Universal Time 1 (UT1) and is a measurement of mean solar time.
Fast forward to 1958 where International Atomic Time (TAI) from the French Temps Atomique International was established. This tracks the time on the Earth's geoid, or its rotating surface, and forms the foundation of today's international time scale system known as Coordinate Universal Time (UTC) from the French Temps Universel Coordonne. We all use the UTC without knowing it, as it's the format (hours, minutes and seconds) your PC uses when it displays the time.
Gathering the time measurements from atomic clocks strategically placed around the world generates UTC. These measurements are used to produce the accurate measurement of the second as defined by the International System of Units (SI). The idea is to produce a time that is as close as possible to the definition of a second.
Just how long is a second?
This is currently based on the frequency of transmission between energy levels in a caesium atom. To be exact, the formal definition is: 'The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom', with the additional qualification in 1997 that, 'This definition refers to a caesium atom at rest at a temperature of absolute zero.'
Just to confuse things further, the time as tracked by TAI, UTC and UT1 don't match precisely because the atomic measurements taken by TAI and UTC don't take the rotation of the Earth into consideration. As we are familiar with UTC time and UT1, these two standards are synchronised together by adding or subtracting a leap second.
The difference between mean solar time and UTC time determines whether a leap second should be added or subtracted. Just think of UTC as universal time that every country sticks to and UT1 as an additional time measurement that some scientists use in their experiments.
Louis Essen and Jack Parry invented the world's first atomic clock, Caesium 1, in 1955 at NPL and changed timekeeping forever. You can see the actual clock on display in the Making the Modern World Gallery at the Science Museum London.
Using the new atomic clock enabled us to clearly define what a second is, and thus, create universal standards that the world could adopt. Clocks had existed before Essen's atomic clock based on other atoms, but his device was the first to show significant improvements over the quartz clocks that had been the standard up until that time.
Atomic clocks basically work by measuring the oscillation of an atom's nucleus and its surrounding electrons. The 'resonance' of the caesium atom (the current standard) forms the basis of UTC time. Atomic clocks can use hydrogen or rubidium atoms, but the most stable and accurate has been found to be caesium 133. However, the story of the atomic clock doesn't stop there.
Keeping time in the US
One of the most accurate clocks in the world is the NIST-F1 Caesium Fountain that is the primary timekeeper for the United States. It's described as a fountain atomic clock because of the way in which the caesium atoms are delivered into the clock's main chamber. Scientists have, however, been experimenting with other elements to try and improve the accuracy of atomic clocks even further.
Optics have also recently been used and combined with strontium atoms to produce an atomic clock that has a 'tick' that is more accurate than the current caesium-based atomic clocks. The mercury ion clock has also been produced that has proven to be even more accurate than the strontium clock.
Earlier this year, physicists at JILA, a joint institute of the Commerce Department's National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder, successfully demonstrated a new strontium clock that is much more accurate than the NIST-F1. The strontium clock's accuracy is astonishing with its designers stating that it would not gain or lose a second in 200 million years.
Two hundred million year question
The key to the new clock's accuracy is that it uses lasers instead of microwaves in the clock, enabling it to divide time into smaller slices. These, in turn, give a more accurate reading when the time is observed. Optical atomic clocks look set to become the future of accurate timekeeping, but research into quantum computers and how they can be applied to timekeeping by NIST could produce the world's first quantum clock that could be even more accurate than optical atomic clocks.
The atomic clocks that contribute to the UTC time we all use in our lives are large and bulky. What if you could shrink an atomic clock and place it on your desk, or miniaturise it even further and place it on a chip? This pioneering work has produced its first prototype that could replace the existing quartz-based clocks that currently offer similar accuracy for their size and power consumption.
Expect to see the standard RTC (Real-Time Clock) in your PC replaced with atomic clock technology as the miniaturisation process continues.
Accurately tracking the time is not just an area of science that is reserved for the world's top research laboratories. Your computer's desktop can also be transformed into an accurate timepiece that will enable you to measure local time, see what the time is anywhere in the world, and use atomic clocks to ensure that your own timepieces are always accurate.
Your PC can be infinitely modified and enhanced to become a window into time. WorldTimeZone.com is a great website to bookmark. Its graphical representation of time zones is superb, as is Timezonecheck. One of the best utilities to synchronise your PC with atomic time is the downloadable Chronograph.
Also available for time enthusiasts is Atomic Time Synchronizer, Atomic Clock Sync, and Absolute Time Corrector. And for a bit of fun, visit death meter which uses your birth date to calculate how long you have left to live.
Swatch attempts to unify time
How about abandoning minutes and seconds altogether? Swatch the Swiss watchmaker wanted to find a way of unifying the world's time. Time zones can be cumbersome, so Swatch invented Beats in 1998. The idea was to divide the mean solar day into 1,000 identical parts or 'beats' that would adopt BMT or Biel Mean Time (as Swatch's headquarters were in Biel, Switzerland).
A range of watches was released that displayed UTC time and the time in beats, but the system never caught on with the general public. You can experiment yourself with a Mac desktop widget and read more about this innovative time platform on the Swatch website.
Hacking atomic clocks has also become the pastime for a group of self-styled time fanatics that have dubbed themselves Time Nuts. As the market has become awash with a greater array of precision timepieces they have been able to experiment with atomic clocks themselves. If you fancy getting your hands dirty, a wide range of digital timepieces can now be bought on eBay, including fully functional atomic clocks.
Carrying along the time with you also has a long history. The Hamilton Watch Company produced the first electric watch in 1957. Three years later Hamilton had perfected its Accutron that used nickel alloy that vibrated when a current was applied to it. Not to be outdone, in 1967, a group of Swiss clockmakers that had grouped together to form CEH (Centre Electronique Horloger), a research lab, perfected the first wristwatch with a quartz movement.
Seiko cracks wristwatch
The Swiss abandoned their research and moved back into traditional timepieces leaving the door open for another player. That turned out to be Seiko, who in 1969 unveiled the Astron, the world's first quartz wristwatch. And 1972 saw the first digital display on the Pulsar, but LED displays were soon outmoded with Seiko once again pioneering the LCD display that has become the mainstay of watch design.
Tracking the time to within thousands of a second has become commonplace. Wristwatches, PDAs and mobile phones can all keep very accurate time, but scientists continue to strive for ever more accurate timepieces based on increasingly exotic substances and technologies.
With the International Space Station due to perform time tracking experiments when it becomes fully operational, we could see a new era of timekeeping evolve with more elements on the periodic table being harnessed to make sure we never again lose a second out of any day.